fc2
NONRESIDENT
TRAINING
COURSE
October 2000
Fire Controlman,
Volume 2–Fire-Control
Radar Fundamentals
NAVEDTRA 14099
DISTRIBUTION STATEMENT A: Approved for public release; distribution is unlimited.
Although the words “he,” “him,” and
“his” are used sparingly in this course to
enhance communication, they are not
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DISTRIBUTION STATEMENT A: Approved for public release; distribution is unlimited.
PREFACE
By enrolling in this self-study course, you have demonstrated a desire to improve yourself and the Navy.
Remember, however, this self-study course is only one part of the total Navy training program. Practical
experience, schools, selected reading, and your desire to succeed are also necessary to successfully round
out a fully meaningful training program.
COURSE OVERVIEW:
following topics:
•
•
•
•
•
•
•
•
After completing this course, you will have a basic knowledge of the
basic radar concepts,
equipment requirements for basic radar systems,
types of energy transmission used in radar systems,
scanning techniques used in radar systems,
major components in today’s radar transmitters,
design requirements of an effective radar receiver,
radiation and other types of hazards associated with maintaining and operating radars, and
safety precautions associated with radar
THE COURSE: This self-study course is organized into subject matter areas, each containing learning
objectives to help you determine what you should learn along with text and illustrations to help you
understand the information. The subject matter reflects day-to-day requirements and experiences of
personnel in the rating or skill area. It also reflects guidance provided by Enlisted Community Managers
(ECMs) and other senior personnel, technical references, instructions, etc., and either the occupational or
naval standards, which are listed in the Manual of Navy Enlisted Manpower Personnel Classifications
and Occupational Standards, NAVPERS 18068.
THE QUESTIONS: The questions that appear in this course are designed to help you understand the
material in the text.
VALUE: In completing this course, you will improve your military and professional knowledge.
Importantly, it can also help you study for the Navy-wide advancement in rate examination. If you are
studying and discover a reference in the text to another publication for further information, look it up.
2000 Edition Prepared by
FCC(SW) Charles F. C. Mellen
Published by
NAVAL EDUCATION AND TRAINING
PROFESSIONAL DEVELOPMENT
AND TECHNOLOGY CENTER
NAVSUP Logistics Tracking Number
0504-LP-022-5620
i
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I will support and defend the
Constitution of the United States of
America and I will obey the orders
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I represent the fighting spirit of the
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before me to defend freedom and
democracy around the world.
I proudly serve my country’s Navy
combat team with honor, courage
and commitment.
I am committed to excellence and
the fair treatment of all.”
ii
TABLE OF CONTENTS
CHAPTER
PAGE
1 Introduction to Basic Radar Systems......................................................................
1-1
2 Fire Control Radar Systems....................................................................................
2-1
3 Radar Safety ...........................................................................................................
3-1
APPENDIX
I References ..............................................................................................................
INDEX
.................................................................................................................................
Course Assignments follow the index.
iii
AI-1
Index-1
INSTRUCTIONS FOR TAKING THE COURSE
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iv
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Course Title:
Fire Controlman, Volume 2—Fire-Control Radar Fundamentals
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vii
CHAPTER 1
INTRODUCTION TO BASIC
RADAR SYSTEMS
LEARNING OBJECTIVES
Upon completing this chapter, you should be able to do the following:
1. Explain the terms “range”, “bearing”, and “altitude” as they are associated with radar.
2. Explain the two basic methods for detecting objects with radar.
3. Identify and explain the use of equipment found in basic radar.
4. Identify and state the use of the four basic types of military radar systems.
5. Identify and explain the three phases of fire-control radar.
6. Identify the radar systems currently used in the U. S. Navy.
INTRODUCTION
BASIC RADAR CONCEPTS
This chapter discusses radar principles and basic
radar systems. As a Fire Controlman, and a possible
work-center supervisor, you must understand basic
radar principles and safety requirements for radar
maintenance. You will find valuable supporting
information in the Navy Electricity and Electronics
Training Series (NEETS), especially Module 18,
Radar Principles, NAVEDTRA 172-18-00-84, and in
Electronics Installation and Maintenance Book,
Radar, NAVSEA SE000-00-EIM-020. By referring to
these publications on a regular basis, you can increase
your understanding of this subject matter.
The term radar is an acronym made from the
words radio, detection, and ranging. It refers to
electronic equipment that uses reflected
electromagnetic energy to determine the direction to,
height of, and distance of detected objects.
Electromagnetic energy of the frequency used for
radar is unaffected by darkness. However, it can be
affected by weather to some degree, depending on its
frequency. It permits radar systems to determine the
positions of ships, planes, and land masses that are
invisible to the naked eye because of distance,
darkness, or weather. Radar systems provide only a
limited field of view and require reference coordinate
systems to define the positions of detected objects.
Radar surface angular measurements are normally
made in a clockwise direction from true north, as
shown in figure 1-1, or from the heading line of the ship
or aircraft. The radar is located at the center of this
coordinate system.
This chapter is not designed to teach you every
radar system the Navy uses, but simply to familiarize
you with the radars and their general characteristics.
Because there are so many different models of radar
equipment, we will describe only the radars and radar
accessories that will be around for several years. We
will not discuss older radar systems that are scheduled
for replacement in the near future. Refer to your
s p e c i fi c t e c h n i c a l p u b l i c a t i o n s f o r d e t a i l e d
descriptions of the operation and maintenance of your
specific radar system.
Table 1-1 defines the basic terms used in figure 1-1.
You must know these terms to understand the
coordinate system.
1-1
Figure 1-1.—Radar surface angular measurements.
Table 1-1.—Radar Reference Coordinate Terms
Term
Definition
Energy pulses
The pulses that are sent out by the radar and are received back from the target.
Reflecting target
The air or surface contact that provides an echo.
True north
The direction of the north geographical pole.
True bearing/azimuth
The angle measured clockwise from true north in the horizontal plane.
Line-of-sight range
The length of the line from the radar set directly to the object.
Vertical plane
All angles in the up direction, measured in a secondary imaginary plane.
Elevation angle
The angle between the horizontal plane and the line of sight.
Horizontal plane
The surface of the Earth, represented by an imaginary flat plane which is
tangent (or parallel) to the Earth’s surface at that location.
1-2
RADAR MEASUREMENTS
peak power of the transmitted pulse; pulse-repetition
frequency (PRF) or pulse-repetition rate (PRR) (PRF
and PRR are synonymous terms.); and receiver
sensitivity, with PRF/PRR as the primary limiting
factor.
We stated earlier that radar is used to determine the
distance and direction to and the height of distant
objects. These three pieces of information are known,
respectively, by the standard terms range, bearing, and
altitude. The use of these standard terms allows anyone
interested in a specific target to establish its position
quickly and accurately. Radar operators determine a
target’s range, bearing, and altitude by interpreting its
position displayed on a specially designed cathode-ray
tube (CRT) installed in a unit known as a plan position
indicator (PPI).
The peak power of a pulse determines how far the
pulse can travel to a target and still return a usable echo.
A usable echo is the weakest signal that a receiver can
detect, process, and present on a display.
The PRR determines the rate at which the range
indicator is reset to zero. As the leading edge of each
pulse is transmitted, the indicator time base used to
measure the returned echo is reset, and a new sweep
appears on the screen.
While most radars are used to detect targets, some
types are used to guide missiles to targets and to direct
the firing of gun systems; other types provide
long-distance surveillance and navigation information.
RANGE ACCURACY.—The shape and width of
the radio-frequency (RF) pulse influences minimum
range, range accuracy, and maximum range. The ideal
pulse shape is a square wave that has vertical leading
and trailing edges. The vertical edge provides a
definite point from which to measure elapsed time on
the indicator time base. A sloping trailing edge
lengthens the pulsewidth. A sloping leading edge
provides no definite point from which to measure
elapsed time on the indicator time base.
Range and bearing (and in the case of aircraft,
altitude) are necessary to determine target movement.
To be a successful radar operator, you must understand
the capabilities and limitations of your radar system in
determining range, bearing, and altitude.
Range
The radar measurement of range (or distance) is
possible due to the properties of radiated
electromagnetic energy. This energy normally travels
through space in a straight line, at a constant speed, and
varies only slightly due to atmospheric and weather
conditions. The frequency of the radiated energy
causes the radar system to have both a minimum
effective range and a maximum effective range.
Other factors affecting range are the antenna’s
height, beamwidth, and rotation rate. A higher antenna
will create a longer radar horizon, allowing a greater
range of detection. An antenna with a narrow
beamwidth, provides a greater range capability, since it
provides more concentrated beam with a higher energy
density per unit area. A slower antenna rotation rate,
providing more transmitted pulses during the sweep,
allows the energy beam to strike each target more
times, providing stronger echo returns and a greater
detection range.
M I N I M U M R A N G E . — R a d a r d u p l exe r s
alternately switch the antenna between the transmitter
and the receiver so that one antenna can be used for
both functions. The timing of this switching is critical
to the operation of the radar and directly affects the
minimum range of the radar system. A reflected pulse
will not be received during the transmit pulse and
subsequent receiver recovery time. The minimum
range of a radar, therefore, is the minimum distance
between the radar’s antenna and a target at which a
radar pulse can be transmitted, reflected from the
target, and received by the radar receiver. If the
antenna is closer to the target than the radar’s minimum
range, any pulse reflected from the target will return
before the receiver is connected to the antenna and will
not be detected.
From the range information, the operator knows
the distance to an object. He now needs bearing
information to determine where the target is in
reference to the ship.
Bearing
Radar bearing is determined by the echo’s signal
strength as the radiated energy lobe moves past the
t a rg e t . S i n c e s e a r c h r a d a r a n t e n n a s m ove
continuously, the point of maximum echo return is
determined either by the detection circuitry as the
beam passes the target or visually by the operator.
Weapons control and guidance radar antennas are
positioned to the point of maximum signal return and
MAXIMUM RANGE.—The maximum range of
a pulse-radar system depends on carrier frequency;
1-3
are maintained at that position either manually or by
automatic tracking circuits.
method of transmitting energy. The most common
method, used for applications from navigation to fire
control, is the pulse-modulation method. The other
method of transmitting is continuous-wave (CW).
CW radars are used almost exclusively for missile
guidance.
You need to be familiar with two types of bearing:
true and relative.
TRUE BEARING.—True bearing is the angle
between true north and a line pointed directly at the
target. This angle is measured in the horizontal plane
and in a clockwise direction from true north.
Pulse Modulation
In the pulse method, the radar transmits the RF in a
short, powerful pulse and then stops and waits for the
return echo. By measuring the elapsed time between
the end of the transmitted pulse and the received echo,
the radar can calculate a range. Pulse radars use one
antenna for both transmitting and receiving. While the
transmitter is sending out its high-power RF pulse, the
antenna is connected to the transmitter through a
special switch called a duplexer. As soon as the
transmitted pulse stops, the duplexer switches the
antenna to the receiver. The time interval between
transmission and reception is computed and converted
into a visual indication of range in miles or yards.
Pulse-radar systems can also be modified to use the
Doppler effect to detect a moving object. The Navy
uses pulse radars to a great extent.
RELATIVE BEARING.—Relative bearing is the
angle between the centerline of the ship and a line
pointed directly at the target. This angle is measured in
a clockwise direction from the bow. Most
surface-search radars provide only range and bearing
information. Both true and relative bearing angles are
illustrated in figure 1-2.
Altitude
Altitude or height-finding radars use a very narrow
beam in the vertical plane. This beam is scanned in
elevation, either mechanically or electronically, to
pinpoint targets. Tracking and weapons-control radar
systems in current use scan the beam by moving the
antenna mechanically or the radiation source
electronically.
Continuous Wave
Most air-search radars use electronic elevation
scanning techniques. Some older air-search radar
systems use a mechanical elevation scanning device;
but these are being replaced by electronically scanning
radar systems.
In a CW radar the transmitter sends out a
“continuous wave” of RF energy. Since this beam of
RF energy is “always on”, the receiver requires a
separate antenna. One disadvantage of this method is
that an accurate range measurement is impossible
because there is no specific “stop time”. This can be
overcome, however, by modulating the frequency. A
frequency-modulated continuous wave (FM-CW)
radar can detect range by measuring the difference
between the transmitted frequency and the received
frequency. This is known as the “Doppler effect”. The
continuous-wave method is usually used by
fire-control systems to illuminate targets for missile
systems.
RADAR TRANSMISSION METHODS
Radar systems are normally divided into two
operational categories (purposes) based on their
RADAR SYSTEM ACCURACY
To be effective, a radar system must provide
accurate indications. That is, it must be able to
determine and present the correct range, bearing, and,
in some cases, altitude of an object. The degree of
accuracy is primarily determined by two factors: the
resolution of the radar system and existing
atmospheric conditions.
Figure 1-2.—True and relative bearings.
1-4
Range Resolution
Range resolution is the ability of a radar to
distinguish between two targets on the same bearing,
but at slightly different ranges. The degree of range
resolution depends on the width of the transmitted
pulse, the types and sizes of the targets, and the
efficiency of the receiver and the indicator.
Bearing Resolution
Figure 1-3.—Ducting effect on the radar wave.
Bearing, or azimuth, resolution is the ability of a
radar system to separate objects at the same range, but
at slightly different bearings. The degree of bearing
resolution depends on the radar’s beamwidth and the
range of the targets. The physical size and shape of the
antenna determines beamwidth. Two targets at the
same range must be separated by at least one
beamwidth to be distinguished as two objects.
usable range. Usable range varies widely with such
weather conditions. The higher the frequency of the
radar system, the more it is affected by weather
conditions, such as rain or clouds.
Other Factors
Some other factors that affect radar performance
are operator skill; size, composition, angle, and
altitude of the target; possible Electronic Attack (EA)
activity; readiness of equipment (completed planned
maintenance system requirements); and weather
conditions.
Atmospheric Conditions
Several conditions within the atmosphere can have
an adverse effect on radar performance. A few of these
are temperature inversion, moisture lapse, water
droplets, and dust particles.
The temperature and moisture content of the
atmosphere normally decrease uniformly with an
increase in altitude. However, under certain conditions
the temperature may first increase with height and then
begin to decrease. Such a situation is called a
temperature inversion. An even more important
deviation from normal may exist over the ocean. Since
the atmosphere close to the surface over large bodies of
water may contain more than a normal amount of
moisture, the moisture content may decrease more
rapidly at heights just above the sea. This effect is
referred to as moisture lapse.
Q1. For radar surface angular measurements, what
is considered to be at the center of the coordinate
system?
Q2. What determines radar bearing?
Q3. What is the most common method of radar
transmission?
Q4. What two factors determine radar accuracy?
BASIC RADAR SYSTEMS
Radar systems, like other complex electronics
systems, are composed of several major subsystems
and many individual circuits. Although modern radar
systems are quite complicated, you can easily
understand their operation by using a basic block
diagram of a pulse-radar system.
Either temperature inversion or moisture lapse,
alone or in combination, can cause a large change in the
refraction index of the lowest few-hundred feet of the
atmosphere. The result is a greater bending of the radar
waves passing through the abnormal condition. This
increase in bending, referred to as ducting, may greatly
affect radar performance. The radar horizon may be
extended or reduced, depending on the direction in
which the radar waves are bent. The effect of ducting is
illustrated in figure 1-3.
FUNDAMENTAL (PULSE) RADAR SYSTEM
Since most radars used today are some variation of
the pulse-radar system, this section discusses
components used in a pulse radar. All other types of
radars use some variation of these units. Refer to the
block diagram in figure 1-4.
Water droplets and dust particles diffuse radar
energy through absorption, reflection, and scattering.
This leaves less energy to strike the target, so the return
echo is smaller. The overall effect is a reduction in
1-5
Duplexer
DUPLEXER
The duplexer is basically an electronic switch that
permits a radar system to use a single antenna to
transmit and receive. The duplexer disconnects the
antenna from the receiver and connects it to the
transmitter for the duration of the transmitted pulse.
The switching time is called receiver recovery time,
and must be very fast if close-in targets are to be
detected.
RECEIVER
Receiver
TRANSMITTER
The receiver accepts the weak RF echoes from the
antenna system and routes amplified pulses to the
display as discernible video signals. Because the radar
frequencies are very high and difficult to amplify, a
superheterodyne receiver is used to convert the echoes
to a lower frequency, called the intermediate frequency
(IF), which is easier to amplify.
DISPLAY
SYNCHRONIZER
SUPPORT
SYSTEMS
COOLING
AIR
POWER
CONTROL
GROUP
Displays
Most of the radars that FCs operate and maintain
have a display, or multiple displays, to provide the
operator with information about the area the radar is
searching or the target, or targets, being tracked. The
usual display is a cathode-ray tube (CRT) that provides
a combination of range, bearing (azimuth), and (in
some cases) elevation data. Some displays provide raw
data in the form of the signal from the radar receiver,
while others provide processed information in the form
of symbology and alphanumerics.
Figure 1-4.—Basic radar block diagram.
Synchronizer
The heart of the radar system is the synchronizer. It
generates all the necessary timing pulses (triggers) that
start the transmitter, indicator sweep circuits, and
ranging circuits. The synchronizer may be classified
as either self-synchronized or externally synchronized. In a self-synchronized system, pulses are
generated within the transmitter. Externally
synchronized system pulses are generated by some
type of master oscillator external to the transmitter,
such as a modulator or a thyratron.
Figure 1-5 shows four basic types of displays.
There are other variations, but these are the major types
encountered in fire control and 3-D search radars.
TYPE A.—The type A sweep, or range sweep,
display shows targets as pulses, with the distance from
the left side of the trace representing range. Variations
in target amplitude cause corresponding changes in the
displayed pulse amplitude. The display may be bipolar
video when used with Moving Target Indicator (MTI)
or pulse Doppler radars.
Transmitter
The transmitter generates powerful pulses of
electromagnetic energy at precise intervals. It creates
the power required for each pulse by using a
high-power microwave oscillator (such as a magnetron) or a microwave amplifier (such as a klystron)
supplied by a low power RF source.
TYPE B.—The type B sweep, or bearing sweep, is
mostly found with gunfire control radars and is used
with surface gunfire to spot the fall of shot. The range
may be full range or an interval either side of the range
gate.
For further information on the construction and
operation of microwave components, review NEETS
Module 11, Microwave Principles, NAVEDTRA
172-11-00-87.
TYPE E.—Two variations of type E are shown.
Both provide range and elevation or height of a target.
These are associated with height-finding radars and are
1-6
Figure 1-5.—Types of radar displays.
Antenna System
generally used to determine the height or elevation
angle only. Range is determined from processing or a
type P display.
The antenna system routes the pulse from the
transmitter, radiates it in a directional beam, picks up
the returning echo, and passes it to the receiver with a
minimum of loss. The antenna system includes the
antenna; transmission lines and waveguide from the
transmitter to the antenna; and transmission lines and
waveguide from the antenna to the receiver.
TYPE P.—This display is commonly called a PPI
(plan position indicator). Own ship is usually the
center. Range is measured radially from the center.
The range display can be selected, and the radar source
is usually selectable. The PPI can display raw video or
symbology and alphanumerics, or both. The type P
display is most commonly found in the Combat
Information Center (CIC) and in weapons control
stations.
Before we discuss some types of antennas used in
fire control, we need to review the basic principles of
electromagnetic wave radiation and reflectors.
The radar energy that forms the target-tracking
and illumination beams is transmitted by an antenna
at the control point. Radiated energy tends to spread
Additional information on how individual displays
are produced is available in NEETS modules 6, 9, and
18.
1-7
out equally in all directions, as shown in figure 1-6.
Figure 1-6 compares the radiation from a radio antenna
with that from a lamp. Both light waves and radio
waves are electromagnetic radiation; the two are
believed to be identical, except in frequency of
vibration. From both sources, energy spreads out in
spherical waves. Unless they meet some obstruction,
these waves will travel outward indefinitely at the
speed of light.
that radio wave energy must be concentrated to be
useful. We can concentrate this energy by mounting a
suitable reflector behind the antenna, to form a large
part of the radiated energy into a relatively narrow
beam. The following paragraphs discuss the more
commonly used reflectors.
PARABOLIC REFLECTORS.—You should be
familiar with the use of polished reflectors to form
beams of light. An automobile headlight uses a
parabolic reflector to produce a fairly wide beam. A
spotlight uses a slightly differently shaped parabolic
reflector to produce a more narrow beam.
The energy at any given point decreases with range
since the wave, and therefore the energy, is spreading
out to cover a larger area. Because of its much higher
frequency, light has a much shorter wavelength than a
radio wave. This is suggested in figure 1-6 but it cannot
be shown accurately to scale. The wavelength of radar
transmission may be measured in centimeters, whereas
the wavelength of light varies from about three to seven
ten-thousandths of a millimeter. We mentioned earlier
A type of reflector generally used in missile
fire-control radars is the parabolic dish. It is similar in
appearance to the reflector used in an automobile
headlight. Since radar operates in the microwave
region of the electromagnetic spectrum, its waves have
properties and characteristics similar to those of light.
This permits radar antennas to be designed using
well-known optical design techniques.
A basic principle of optics is that a light ray
striking a reflecting surface at a given angle will reflect
from that surface at the same angle. Now refer to figure
1-7. Think of the circular wavefronts generated by
source F as consisting of an infinite number of rays.
The antenna’s parabolic reflecting surface is designed,
using the reflection principle, so that as the circular
wavefronts strike the reflector, they are reflected as
straight wavefronts. This action concentrates them
into a narrow circular beam of energy.
HORN RADIATORS.—Horn radiators (fig.
1-8), like parabolic reflectors, may be used to create
concentrated electromagnetic waves. Horn radiators
are readily adaptable for use with waveguides because
they serve both as an impedance-matching device and
LIGHT
F
RADIO
Figure 1-6.—Radiation waves from a radio antenna
and a lamp.
Figure 1-7.—Principles of the parabolic reflector.
1-8
the beam. (The shadow is a dead spot directly in front
of the feedhorn.) To solve this problem the feedhorn
can be offset from center (fig. 1-9, view B). This takes
it out of the path of the RF beam, thus eliminating the
shadow.
LENS ANTENNA.—Another antenna that can
change spherical waves into flat plane waves is the lens
antenna. This antenna uses a microwave lens, which is
similar to an optical lens to straighten the spherical
wavefronts. Since this type of antenna uses a lens to
straighten the wavefronts, its design is based on the
laws of refraction, rather than reflection.
Figure 1-8.—Horn radiators.
as a directional radiator. Horn radiators may be fed by
coaxial or other types of lines.
Horns are constructed in a variety of shapes, as
illustrated in figure 1-8. The shape of the horn, along
with the dimensions of the length and mouth, largely
determines the beam’s shape. The ratio of the horn’s
length to mouth opening size determines the
beamwidth and thus the directivity. In general, the
larger the opening of the horn, the more directive is the
resulting field pattern.
Two types of lenses have been developed to
provide a plane-wavefront narrow beam for tracking
radars, while avoiding the problems associated with
the feedhorn shadow. These are the conducting
(acceleration) type and the dielectric (delay) type.
The lens of an antenna is substantially transparent
to microwave energy that passes through it. It will,
however, cause the waves of energy to be either
converged or diverged as they exit the lens. Consider
the action of the two types of lenses.
FEEDHORNS.—A waveguide horn may be used
to feed into a parabolic dish. The directivity of this
horn, or feedhorn, is then added to that of the parabolic
dish. The resulting pattern (fig. 1-9, view A) is a very
narrow and concentrated beam. Such an arrangement
is ideally suited for fire control use. In most radars, the
feedhorn is covered with a window of polystyrene
fiberglass to prevent moisture and dirt from entering
the open end of the waveguide.
The conducting type of lens is illustrated in figure
1-10, view A. This type of lens consists of flat metal
strips placed parallel to the electric field of the wave
and spaced slightly in excess of one-half of a
wavelength. To the wave these strips look like parallel
waveguides. The velocity of phase propagation of a
wave is greater in a waveguide than in air. Thus, since
the lens is concave, the outer portions of the
transmitted spherical waves are accelerated for a
longer interval of time than the inner portion. The
One problem associated with feedhorns is the
shadow introduced by the feedhorn if it is in the path of
Figure 1-10.—Antenna lenses: A. Conducting (acceleration)
type of microwave lens; B. Dielectric (delay) type of
microwave lens.
Figure 1-9.—Reflector with feedhorn.
1-9
spherical waves emerge at the exit side of the
conducting lens (lens aperture) as flat-fronted parallel
waves. This type of lens is frequency sensitive.
wavefront flat before it is radiated by the source feed.
The relative phase between elements determines the
position of the beam; hence the often used term,
phased array. This phase relationship is what allows
the beam to be rotated or steered without moving the
antenna. This characteristic of array antennas makes it
ideal for electronic scanning or tracking. (We will
discuss scanning shortly.)
The dielectric type of lens, shown in figure 1-10,
view B, slows down the phase propagation as the wave
passes through it. This lens is convex and consists of
dielectric material. Focusing action results from the
difference between the velocity of propagation inside
the dielectric and the velocity of propagation in the air.
The result is an apparent bending, or refracting, of the
waves. The amount of delay is determined by the
dielectric constant of the material. In most cases,
artificial dielectrics, consisting of conducting rods or
spheres that are small compared to the wavelength, are
used. In this case, the inner portions of the transmitted
waves are decelerated for a longer interval of time than
the outer portions.
Radomes
The term radome is a combination of the words
radar and dome. Radomes are used to cover and
protect radar antennas from environmental effects such
as wind, rain, hail, snow, ice, sand, salt spray,
lightening, heat, and erosion. The ideal radome is
transparent to the RF radiation from the antenna and its
return pulses and protects the antenna from the
environment. A radome’s design is based on the
expected environmental factors and the mechanical
and electronic requirements of the RF antenna.
In a lens antenna, the exit side of the lens can be
regarded as an aperture across which there is a field
distribution. This field acts as a source of radiation,
just as do fields across the mouth of a reflector or horn.
For a returning echo, the same process takes place in
the lens.
Although, in theory, a radome may be invisible to
RF energy, in real life the radome effects antenna’s
performance in four ways. These are; beam deflection,
transmission loss, reflected power, and secondary
effects. Beam deflection is the shift of the RF beam’s
axis. This is a major consideration with tracking (i.e.
FC) radar. Transmission loss is the loss of energy
associated with reflection and absorption within the
radome. Reflected power can cause antenna mismatch
in small radomes and sidelobes in large radomes.
Depolarization and increased antenna noise are a result
of secondary effects.
ARRAY ANTENNAS.—An array type of
antenna is just what the name implies—an array or
regular grouping of individual radiating elements.
These elements may be dipoles, waveguide slots, or
horns. The most common form of array is the planar
array, which consists of elements linearly aligned in
two dimensions—horizontal and vertical—to form a
plane (fig. 1-11).
Unlike the lens or parabolic reflector, the array
applies the proper phase relationship to make the
As an FC, you will be primarily responsible
maintaining the radome associated with your
equipment. This normally will include routine
cleaning and inspection according to your prescribed
preventive maintenance schedule. Some minor repairs
may be authorized by your technical manuals, but most
repairs will normally be done by an authorized factory
representative. You may be required to repaint the
radome because of normal environmental wear and
tear. If so, be especially careful to use only paint(s)
authorized by the manufacturer and to follow the
authorized step-by-step procedures.
HORIZONTAL LINEAR
SUBARRAY
TRANSMITTER AND RECEIVER
SLOT
ANTENNA
Figure 1-12 is an example of a radome in use in
today’s Navy. Other systems that use radomes include,
the Combined Antenna System of the Mk 92 Fire
Control System, the AN/SPQ-9 series antenna for the
Mk 86 Gun Fire Control System, and the Mk 23 Target
FCRf0111
Figure 1-11.—Planar array antenna.
1-10
3A1A1
SEARCH RADAR
RADOME ASSEMBLY
NOTE:
CABLING
DETAILS
OMITTED
FOR CLARITY
from the ship’s primary power source, it has other
voltage requirements that may be stepped up, stepped
down, or converted in order to make the radar fully
operational. High-voltage amplifiers and peripheral
equipment associated with producing RF energy create
tremendous amounts of heat. Chilled water systems
remove excessive heat from such equipment. Cooling
systems may be either liquid-to-liquid or liquid-to-air
types that use either sea water, or chilled water
provided by the ship itself. Another important support
system is the dry air system. Dry air is used for keeping
the internal part of the waveguide assembly moisture
free and to aid in properly conducting the RF energy
being transmitted. The dry air may be either air taken
from ship spaces and circulated through various filters
or dehydrated air provided by the ship. Some systems
use a special gas for their waveguides. An example of
this is the Mk 92 Fire Control System, which uses the
gas SF6 for its Continuous Wave Illumination (CWI)
mode.
3A1A2
SEARCH
RADAR
ANTENNA
ASSEMBLY
3A1A7
TRACK
ANTENNA
FORWARD
3A1A13
TRACK
RADAR
RADOME
These are very important support systems to your
radar. As you know, any system is only as good as its
weakest link. Therefore, you must be sure to maintain
the support equipment as required by the equipment’s
technical manuals and maintenance instructions.
Stable Elements
LEFT SIDE CUTAWAY VIEW
FCRf0112
Hitting a target on a regular basis requires that the
gun or launcher be stable in relation to the target.
Ideally, the platform on which the gun or launcher is
mounted is stable throughout the target acquisition and
destruction cycle. Unfortunately Navy ships, on which
the guns and launchers are mounted, are seldom stable.
In even the calmest sea, they pitch and roll to some
extent. The solution lies in stabilizing the guns and
launchers while the ship continues to pitch and roll.
This is done with gyroscopes (gyros) installed in the
fire control systems.
Figure 1-12.—Example of a search and track radome.
Acquisitioning System for the SEASPARROW
missile system.
Control Group
The Control Group provides computer control for
an equipment group, processes target detections to
develop and maintain a track file, and interfaces with
the specific weapon system being used. The Control
Group normally consists of the following equipment: a
computer, data terminal set, magnetic tape unit, and
test set.
Gyros provide a stable platform, called the
horizontal plane, as an unvarying reference from
which the fire control problem is computed. The basic
fundamentals and functions of gyros are covered in
NEETS Module 15—Principles of Synchros, Servos,
and Gyros.
Support Systems
The equipment we discussed above composes the
core of the radar system. To operate properly and
efficiently, it requires a certain amount of support
equipment. Examples of such equipment include
power supplies (some also have frequency converters),
chilled water systems, and dry air systems. Although
your radar system normally receives 440 VAC directly
In fire control, we call the stabilizing unit a stable
element. As its name implies, the stable element uses a
stabilizing gyro. The stabilizing gyro is also the
primary reference for navigation of the ship. It gives
the ship a true North reference for all navigational
equipment. The WSN-2 or WSN-5 are examples of
1-11
stabilizing gyros used in today’s ships. The
maintenance and operation of these gyros is the
responsibility of the Interior Communications (IC)
technicians. Figure 1-13 shows a phantom view of a
gyro you might see on your ship.
development of a joint-services classification system
for accurate identification of radars. Radar systems are
usually classified according to their specific function
and installation vehicle. The joint-service
standardized classification system divides these broad
categories for more precise identification.
The primary purpose of the stable element for fire
control equipment is to measure accurately any
deviation of the reference element (antenna, director,
launcher, etc.) from the horizontal plane. Deviation
measurements are sent to the fire control computer to
create a stationary foundation from which to solve the
fire control problem. They are also sent to the gun
director, radar antenna, or optical equipment,
depending upon the fire control system, to stabilize
these units of the fire control system.
Since no single radar system can fulfill all the
requirements of modern warfare, most modern
warships, aircraft, and shore installations have several
radar sets, each performing a specific function. A
shipboard radar installation may include
surface-search and navigation radars, a 3D radar, an
air-search radar, and various fire-control radars.
Figure 1-14 is a listing of equipment identification
indicators. You can use this table and the radar
nomenclature to identify the parameters of a particular
radar set. The example given explains the equipment
indicators for the AN/SPY-1A radar system.
Q5. What is the switching time of a duplexer called?
Q6. What are the two types of lens antennas?
Q7. What determines the position of a phased array
antenna beam?
The letters AN were originally adopted by the
Joint Army-Navy Nomenclature System, also known
as the AN system, to easily classify all military
electronic equipment. In 1985, Military Standard
MIL-STD-196D changed the name of the Joint
Army-Navy Nomenclature System to the “Joint
Electronics Type Designation System (JETDS)”, but
the letters AN are still used in identifying military
electronics equipment.
Q8. What part of a radar system provides computer
control for an equipment group?
Q9. What is the primary purpose of the stable
element for fire control equipment?
TYPES OF RADAR SYSTEMS
Because of different design parameters, no single
radar set can perform all the many radar functions
required for military use. The large number of radar
systems used by the military has forced the
AIR-SEARCH RADAR
The primary function of an air-search radar is to
maintain a 360-degree surveillance from the surface to
high altitudes and to detect and determine ranges and
bearings of aircraft targets over relatively large areas.
The following are some uses of an air-search radar:
• Give early warning of approaching enemy
aircraft and missiles, by providing the direction
from which an attack could come. This allows
time to bring antiaircraft defenses to the proper
degree of readiness and to launch fighters if an
air attack is imminent.
• Observe constantly the movement of enemy
aircraft. When it detects an enemy aircraft,
guide combat air patrol (CAP) aircraft to a
position suitable for an intercept.
• Provide security against attacks at night and
during times of poor visibility.
• Provide information for aircraft control during
operations that require a specific geographic
Figure 1-13.—Phantom view of a gyro.
1-12
Figure 1-14.—AN equipment indicator system.
track (such as an antisubmarine barrier or a
search and rescue pattern).
The following are some applications of a
multi-dimensional radar:
Together, surface- and air-search radars provide a
good early-warning system. However, the ship must be
able to determine altitude to effectively intercept any
air target. This requires the use of another type of radar.
• Obtain range, bearing, and altitude data on
enemy aircraft and missiles to assist in the
guidance of CAP aircraft.
• Provide precise range, bearing, and height
information for fast and accurate initial
positioning of fire-control tracking radars.
MULTI-DIMENSIONAL RADAR
• Detect low-flying aircraft.
The primary function of a multi-dimensional radar
is to compute accurate ranges, bearings, and altitudes
of targets detected by an air-search radar. This
information is used to direct fighter aircraft during
interception of air targets.
• Determine the range to distant landmasses.
• Track aircraft over land.
• Detect certain weather phenomena.
• Track weather balloons.
The multi-dimensional radar is different from the
air-search radar in that it has a higher transmitting
frequency, higher output power, and a much narrower
vertical beamwidth. In addition, it requires a stabilized
antenna for altitude accuracy.
The modern warship has several radars. Each
radar is designed to fulfill a particular need, but it may
also be capable of performing other functions. For
example, most multi-dimensional radars can be used as
1-13
secondary air-search radars; in emergencies,
fire-control radars have served as surface-search
radars. A multi-dimensional air-search radar is shown
in figure 1-15.
MISSILE GUIDANCE RADAR
The purpose of a guidance subsystem is to direct
the missile to target intercept regardless of whether or
not the target takes deliberate evasive action. The
guidance function may be based on information
provided by a signal from the target, information sent
from the launching ship, or both. Every missile
guidance system consists of two separate systems—an
attitude control system and a flight path control
system. The attitude control system maintains the
missile in the desired attitude on the ordered flight path
by controlling it in pitch, roll, and yaw (fig. 1-16). This
action, along with the thrust of the rocket motor, keeps
the missile in stabilized flight. The flight path control
system guides the missile to its designated target. This
is done by determining the flight path errors,
generating the necessary orders needed to correct these
errors, and sending these orders to the missile’s control
subsystem. The control subsystem exercises control in
such a way that a suitable flight path is achieved and
maintained. The operation of the guidance and control
subsystems is based on the closed-loop or servo
principle (fig. 1-17). The control units make corrective
adjustments to the missile control surfaces when a
guidance error is present. The control units also adjust
the wings or fins to stabilize the missile in roll, pitch,
and yaw. Guidance and stabilization are two separate
processes, although they occur simultaneously.
Figure 1-16.—Missile axes: pitch, roll, yaw.
Figure 1-17.—Basic missile guidance and control systems.
phases are boost, midcourse, and terminal.
STANDARD SM-2 missiles (MR & ER) use all three
of these phases. Not all missiles, however, go through
the three phases. As shown in figure 1-18, some
missiles (STANDARD SM-1, SEASPARROW) do
not use midcourse guidance. With that thought in
mind, let’s examine each phase, beginning with boost.
I N I T I A L ( B O O S T ) P H A S E . — N av y
surface-launched missiles are boosted to flight speed
by the booster component (which is not always a
separate component) of the propulsion system. The
boost period lasts from the time the missile leaves the
launcher until the booster burns up its fuel. In missiles
with separate boosters, the booster drops away from
the missile at burnout (fig. 1-18, view A). Discarding
the burnt-out booster shell reduces the drag on the
missile and enables the missile to travel farther. SMS
missiles with separate boosters are the STANDARD
(ER) and HARPOON.
Phases of Guidance
Missile guidance is generally divided into three
phases (fig. 1-18). As indicated in the figure, the three
The problems of the initial (boost) phase and the
methods of solving them vary for different missiles.
The method of launch is also a factor. The basic
purposes, however, are the same. The missile can be
either pre-programmed or physically aimed in a
specific direction on orders from the fire control
Figure 1-15.—Multi-dimensional (3-D) radar.
1-14
A.
B.
Figure 1-18.—Guidance phases of missile flight.
computer. This establishes the line of fire (trajectory
or flight path) along which the missile must fly during
the boosted portion of its flight. At the end of the boost
period, the missile must be at a precalculated point.
MIDCOURSE PHASE.—Not all guided missiles
have a midcourse phase; but when present, it is often
the longest in both time and distance. During this part
of flight, changes may be needed to bring the missile
onto the desired course and to make certain that it stays
on that course. In most cases, midcourse guidance is
used to put the missile near the target, where the final
phase of guidance can take control. The HARPOON
and STANDARD SM-2 missiles use a midcourse
phase of guidance.
There are several reasons why the boost phase is
important. If the missile is a homing missile, it must
“look” in a predetermined direction toward the target.
The fire control computer (on the ship) calculates this
predicted target position on the basis of where the
missile should be at the end of the boost period. Before
launch, this information is fed into the missile.
When a beam-riding missile reaches the end of its
boosted period, it must be in a position where it can be
captured by a radar guidance beam. If the missile does
not fly along the prescribed launching trajectory as
accurately as possible, it will not be in position to
acquire the radar guidance beam and continue its flight
to the target. The boost phase guidance system keeps
the missile heading exactly as it was at launch. This is
primarily a stabilizing function.
TERMINAL PHASE.—The terminal or final
phase is of great importance. The last phase of missile
guidance must have a high degree of accuracy, as well
as fast response to guidance signals to ensure an
intercept. Near the end of the flight, the missile may be
required to maneuver to its maximum capability in
order to make the sharp turns needed to overtake and
hit a fast-moving, evasive target. In some missiles,
maneuvers are limited during the early part of the
terminal phase. As the missile gets closer to the target,
it becomes more responsive to the detected error
signals. In this way, it avoids excessive maneuvers
during the first part of terminal phase.
During the boost phase of some missiles, the
missile’s guidance system and the control surfaces are
locked in position. The locked control surfaces
function in much the same manner as do the tail
feathers of a dart or arrow. They provide stability and
cause the missile to fly in a straight line.
1-15
Types of Guidance
keeps the beam pointed at the target and the missile
“rides” the beam to the target.
As we mentioned earlier, missiles have a path
control system and an attitude control system.
Guidance systems are usually classified according to
their path control system, since many missiles use the
same type of attitude control. The type of attitude
control used in the fleet is inertial. The following is a
discussion of the types of path control (guidance) in
use in SMS missiles.
Figure 1-20 illustrates a simple beam rider
guidance system. As the beam spreads out, it is more
difficult for the missile to sense and remain in the
center of the beam. For this reason, the accuracy of the
beam-rider decreases as the range between the missile
and the ship increases. If the target is crossing (not
heading directly at the firing ship), the missile must
follow a continually changing path. This may cause
excessive maneuvering, which reduces the missile’s
speed and range. Beam-riders, therefore, are effective
against only short- and medium-range incoming
targets.
INERTIAL GUIDANCE.—An inertial guidance
system is one that is designed to fly a predetermined
path. The missile is controlled by self-contained
automatic devices called accelerometers.
Accelerometers are inertial devices that measure
accelerations. In missile control, they measure the
vertical, lateral, and longitudinal accelerations of the
controlled missile (fig. 1-19). Although there may not
be contact between the launching site and the missile
after launch, the missile is able to make corrections to
its flight path with amazing precision.
HOMING GUIDANCE.—Homing guidance
systems control the path of the missile by means of a
device in the missile that detects and reacts to some
distinguishing feature of (or signal from) the target.
This may be in the form of light, radio, heat, sound
waves, or even a magnetic field. The homing missiles
use radar or RF waves to locate the target while
air-to-air missiles sometimes use infrared (heat)
waves.
During flight, unpredictable outside forces, such
as wind, work on the missile, causing changes in speed
commands. These commands are transmitted to the
missile by varying the characteristics of the missile
tracking or guidance beam, or by the use of a separate
radio uplink transmitter.
Since the system tracks a characteristic of the
target or energy reflecting off the target, contact
between the missile and target is established and
maintained. The missile derives guidance error signals
based on its position relative to the target. This makes
homing the most accurate type of guidance system,
which is of great importance against moving air
targets. Homing guidance methods are normally
divided into three types:, active homing, semi-active
homing, and passive homing (fig. 1-21).
BEAM-RIDER GUIDANCE.—A beam-rider
guidance system is a type of command guidance in
which the missile seeks out the center of a controlled
directional energy beam. Normally, this is a narrow
radar beam. The missile’s guidance system receives
information concerning the position of the missile
within the beam. It interprets the information and
generates its own correction signals, which keep the
missile in the center of the beam. The fire control radar
Active Homing.—With active homing, the missile
contains both a radar transmitter and a receiver. The
transmitter radiates RF energy in the direction of the
Figure 1-19.—Accelerometers in a guided missile.
1-16
A.
B.
Figure 1-20.—Simplified command guidance systems: A. Radar/radio command; B. Beam rider.
target (fig. 1-21, view A). The RF energy strikes the
target and is reflected back to the missile. (This
process is referred to as “illuminating the target.”) The
missile seeker (receiving) antenna detects the reflected
energy and provides it as an input to the missile
guidance system. The guidance system processes the
input, usually called the homing error signal, and
develops target tracking and missile control
information. Missile control causes the missile to fly a
desired flight path.
The missile, throughout its flight, is between the
target and the radar that illuminates the target. It will
receive radiation from the launching ship, as well as
reflections from the target. The missile must therefore
have some means of distinguishing between the two
signals, so that it can home on the target rather than on
the launching ship. This can be done in several ways.
For example, a highly directional antenna may be
mounted in the nose of the missile; or the Doppler
principle may be used to distinguish between the
transmitter signal and the target echoes. Since the
missile is receding from the transmitter and
approaching the target, the echo signals will be of a
higher frequency. Most SMS missiles use both of these
methods.
The effective range of the missile transmitter is
somewhat limited because of its size (power output).
For this reason, relatively long-range missiles, such as
HARPOON, do not switch to active guidance until
after midcourse guidance has positioned the missile so
that the transmitter is within its effective range.
A drawback of this system is that the shipboard
illumination is not free to engage another target while
the missile is in flight. STANDARD SM-1 and SEASPARROW all use semi-active homing as their
primary guidance; they do not use midcourse
guidance. The STANDARD SM-2 uses midcourse
guidance, and then semi-active homing only for
terminal guidance. As a result, the SM-2 needs
illumination from the ship only for the last few seconds
of flight.
Semiactive Homing.—In a semiactive homing
system, the target is illuminated by a transmitter (an
illuminator) on the launching site (fig. 1-21, view B).
As with active homing, the transmitted RF is reflected
by the target and picked up by the missile’s receiver.
The fact that the transmitter’s size is not limited, as
with active homing, allows a much greater range.
1-17
switching to the passive home-on-jamming (HOJ)
mode in a countermeasure environment. That is, if
the target detects that it is being illuminated by an
active or semiactive guidance radar and initiates
jamming (RF interference), the missile will home on
the jamming signal if it is unable to maintain track on
the reflected illumination signal.
Tracking Radar/Fire-Control Radar
A.
Radar that provides continuous positional data is
called tracking radar. Most tracking radar systems
used by the military are also called fire-control radars,
the two names being interchangeable. A fire-control
tracking radar system produces a very narrow,
circular beam.
PHASES OF RADAR OPERATION
The three sequential phases of radar operation
(designation, acquisition, and track) are often
referred to as modes and are common to the
target-processing sequence of most fire-control
radars.
B.
Designation Phase
During the designation phase, the fire-control
radar is directed to the general location of the target.
Acquisition Phase
The fire-control radar switches to the acquisition
phase once its beam is in the general vicinity of the
target. During this phase, the radar system searches in
the designated area in a predetermined search pattern
until it either locates the target or is redesignated.
C.
Figure 1-21.—Homing guidance: A. Active homing; B.
Semi-active homing; C. Passive homing.
Passive Homing.—Passive homing requires that
the target be a source of radiated energy (fig. 1-21, view
C). Typical forms of energy used in passive homing are
heat, light, and RF energy. One of the most common
uses of passive homing is with air-to-air missiles that
use heat-sensing devices. It is also used with missiles
that home on RF energy that originates at the target
(ships, aircraft, shore-based radar, and so forth). An
ex a m p l e o f t h i s i s t h e S TA N DA R D A R M
(anti-radiation missile) used for both air-to-surface and
surface-to-surface engagements. An advantage of this
type of homing is that the target cannot detect an attack
because the target is not illuminated.
Several missiles that normally use other homing
methods (active or semi-active) are capable of
1-18
Track Phase
The fire-control radar enters into the track phase
when it locates the target. The radar system locks on
to the target during this phase.
Typical fire-control radar characteristics include
high pulse-repetition frequency, a very narrow
pulsewidth, and a very narrow beamwidth. A typical
fire-control antenna is shown in figure 1-22.
Detect-to-Engage Sequence
The basic sequence can be divided into six
fundamental operations: detection, acquisition and
tracking, prediction, launcher/gun positioning,
information until it locks on the reflected target signal
(acquisition). Either an operator or an automatic
control circuit maintains that alignment (track) while
the ship and target are moving. In this way,
continuous, accurate target position information is
available to the weapon system for processing. Not
only is the continuous present position of the target
obtained, but its movement (course and speed) is also
determined.
Data other than target data is equally important for
weapon flight path (trajectory) determination. Wind,
for example, could blow the weapon off its flight path.
Appropriate corrections would require that wind
direction and velocity be determined. The course and
speed of the launching ship and its motion, because of
the sea (pitch and roll), are also important
considerations. If this type of data is not included in
the flight path determinations, it could cause large
errors in the flight path (trajectory).
Data of this nature, along with target data, is
transmitted to the fire control system’s computer. The
computer performs the necessary calculations for
computing the launcher or gun mount position angles
and the weapon’s flight path.
After target detection and target acquisition have
occurred, the fire control system provides three
operations for the tracking, computation (prediction),
and positioning functions.
The first operation tracks the target and provides
all necessary data on the target. The fire control radar
performs this function by establishing a tracking Line
Of Sight (LOS) along which it receives the returned or
reflected energy from the target. It also provides
accurate range data.
Figure 1-22.—Typical fire-control radar.
guidance (missiles), and evaluation (intercept and
target destruction). Figure 1-23 illustrates the fire
control problem sequence.
Since the speed of the propagated RF energy is
about 186,000 miles per second (the same as the speed
of light), and since the target ranges involved are
relatively small, the time for the energy to travel to and
from the target can be considered as instantaneous.
Therefore, the radar indications of the target can be
considered as instantaneous, present-target positions.
DETECTION.—In this phase, the radar looks for
a target. After the radar (usually a search radar) detects
a target, the system obtains precise target position
information. This information can be provided by the
same source that detected the target, or it can be
provided from some other source, such as another
radar. In the majority of the cases, a second radar, a fire
control radar, is used.
PREDICTION.—The second operation of the
fire control problem that must be performed is the
computation of the gun/launcher positioning angle
(line of fire) and the weapon flight path trajectory. This
operation consists of two parts. First, the system
processes received data into a usable form. Then the
fire control computer performs arithmetic operations
to predict the future position of the target.
The search radar establishes the target’s initial
position and transmits this information to the
designated fire control system.
ACQUISITION AND TRACKING.—During
this phase, the fire control radar director/antenna is
aligned with the search radar’s target position
1-19
DETECTION
ACQUISITION
AND
TRACKING
PREDICTION
GUN OR
LAUNCHER
POSITIONING
GUIDANCE
EVALUATION
FCRf0123
Figure 1-23.—Fire-control problem sequence.
own flight path. If the target maneuvers during the
missile’s flight, the computer can send course
correction data to the missile via the fire control radar
or the missile can correct itself.
LAUNCHER/GUN POSITIONING.—The
third operation that must be performed is the
positioning of the gun/launcher, based on the
calculated line of fire to the future target position. This
amounts to using the gun/launcher drive mechanism to
offset the gun/launcher axis from the LOS by the
amount of the predicted lead angle. In some cases, the
missile is positioned (guided) in flight by the fire
control system.
EVALUATION.—The fire control radar displays
are used to evaluate the weapon’s destruction of the
target. If the missile misses the target or causes only
minor damage, additional weapons can be used. In
missile fire control, another missile is fired. In gun fire
control, corrections are made to bring the fall of shot
onto a target using the radar indicators, optical
devices, or spotter corrections. Normally, a target
will be fired at until it is evaluated as either destroyed
or damaged to the point it is no longer a threat.
GUIDANCE (MISSILES).—For the Guided
Missile Fire Control System (GMFCS), additional
functions must be performed during the time the
missile is in flight. Prior to launching, the fire control
computer performs certain computations to provide
the missile with information about the target and its
1-20
Q10. What type of radar system provides early
warning of approaching enemy aircraft or
missiles?
RADAR SYSTEMS IN TODAY’S NAVY
There are too many radar systems used in today’s
Navy to cover in this volume. However, table 1-2
provides an overview of the radars and sensors in use,
by AN system designator, ship class, and related FC
systems.
Q11. What phase of guidance is NOT necessary for
some missiles
Q12. What are the three types of homing guidance
used for missiles?
SUMMARY
Radio, detecting, and ranging (radar) uses radio
frequency (RF) energy and a complex integration of
computers, displays, and support equipment to detect a
target. However, radar is just one type of sensor that is
available to the modern Fire Controlman. Other types
of sensors (e.g., infrared and optical) use different
Q13. What are the three sequenti8al phases of radar
operation?
Q14. In what phase of the fire control problem
sequence does fore control radar first play a
part?
Table 1-2.—Radar Systems in the U. S. Navy
Designator
Type
Range
Ship Class
Weapon/Function
Related FC
System
SEARCH
SPS 48 C/E/F
SPS 52 C
3D Air Search,
phased array
LHA, LCC, LHD
CV/CVN,
3D Air Search
LHD
220 NM
Primary Search
SYS-1,SYS-2
240 NM
Primary Search
SYS-1
FIRE CONTROL
Fire Control,
Mk 92 CAS
Track-While-Scan,
(Combined
Antenna Systems) Search
FFG
25 NM
Mk 75 Gun, SM-1
missiles
Part of Mk 92 FCS
Mk 95 radar
DD (Spruance),
20 NM
SEASPARROW
missiles
Mk 23 TAS,
Part of Mk 91 FCS
Fire Control, CW
tracker, illuminator
CV/CVN
SPG 51 D
Fire Control,
pulse-doppler,
COSRO tracker,
CWI
DDG (Kidd)
100 NM
SM-1(MR) missiles, Part of Mk 74 FCS
SM-2 missiles
SPG 60
Fire Control
DD (Spruance),
50 NM
SM-1/2 missiles,
Mk 45 LWG
SPY-1, Mk 86 GFCS
20 NM
SM-2 missiles
SPY-1,
Part of Mk 99 FCS
20 NM
SM-1/2 missiles
Mk 45 LWG
SPY-1
Mk 86 GFCS
60 NM
Mk 75 Gun,
SM-1 missiles
Part of Mk 92 FCS
DDG (Kidd)
SPG 62
Fire Control, CW,
illuminator
DDG (Arleigh
Burke),
CG (Ticonderoga)
SPQ 9 Series
STIR (Separate
Target
Illuminating
Radar)
Fire Control,
Track-While-Scan,
(Surface),
pulse-doppler
DD (Spruance),
DDG (Kidd),
Fire Control,
monopulse trackerilluminator
FFG
CG (Ticonderoga),
LHA
1-21
Table 1-2.—Radar Systems in the U.S. Navy—Continued
Designator
Type
Range
Ship Class
Weapon/Function
Related FC
System
OTHER
ALL
Anti-ship missile
5 NM
Search 1 NM and air defense
track
None
HF Surface Wave FM CW
LSD
6-12 NM
Anti-ship missiles
Sea Skimmer
missile
Detection/Air (This
radar is still in
development)
Air search, CW,
Mk 23 TAS
(Target Acquistion tracker/illuminator
System)
20 NM
DD (Spruance),
CV/CVN, LCC, LHD,
LHA, LPD 17
SEASPARROW
missiles
Part of Mk 91
FCS/Mk 95 Radar
SPY 1 Series
D for DDG (Arleigh
Burke), D for
CG (Ticonderoga)
SM-2 missiles;
search, track, and
missile guidance,
Mk 45 LWG
AEGIS, Mk 34
GWS, Mk 86 GFCS,
Mk 99 FCS
CIWS (Close-In
Weapon System)
Combined (search
and track),
pulse-doppler
Multi-function,
phased array
FFG, LHD, LSD,
SSDS Mk 1 (Ship Integrated use of
multiple ship sensors LPD 17, AOE 6
Self-Defense
System)
>100 NM
Range as per CIWS/RAM, SLQ
each sensor
32, SPS 49,
SEASPARROW
missiles
Mk 2 replaces
NATO
SEASPARROW
with ESSM
(Evolved
SEASPARROW
missile)
OPTRONICS SYSYEMS
Optical Sighting
System (OSS) or
Remote Optical
Sighting System
(ROS)
Sensor/View finder
Arleigh Burke (DDG), 20 km
Ticonderoga (CG)
surface, 10
km air
Mk 45 LWG
MK 34 GWS, MK
86 GFCS
FLIR (Forward
Looking Infrared)
Sensor
All ships upgraded to Surface/Air
Block 1B
Mk 15 Mods 11-14
CIWS Block 1 B
TISS (Thermal
Imaging Sensor
System)
Sensor
Arleigh Burke (DDG), 55 kyd/air,
Ticonderoga (CG),
45 kyd
AOE-6, CV/CVN,
surface
LPD-17, LSD-41,
LHD/LKA, DDG 993,
DD 963
Mk 31 RAM
(Rolling Airframe
Missile), CIWS,
SSDS
AEGIS, Mk 86
GFCS
parts of the electromagnetic spectrum. It is important
that you, as a modern Fire Controlman, understand the
basic concepts of the sensors used on your ship and
other ships in the Navy. These sensors play a key part
in accomplishing the ship’s mission. As sensor
technology improves, the Fire Controlman of the
future will be expected to have a broader spectrum of
knowledge and experience in order to keep our Navy
on the cutting edge of naval warfare.
1-22
ANSWERS TO CHAPTER QUESTIONS
A7. The relative phase between elements.
A8. The control group.
A1. The radar.
A9. To measure accurately any deviation of the
reference element from the horizontal plane.
A2. Radar bearing is determined by the echo signal
strength as the radiated energy lobe moves past a
target.
A10. Air-search radar.
A3. Pulse-modulation.
A11. Mid-course guidance.
A4. The resolution of the radar system and
atmospheric conditions.
A12. Active, semi-active, and passive homing.
A13. Designation, acquisition, and track.
A5. Receiver recovery time.
A14. The acquisition and tracking phase.
A6. Conducting (acceleration) and dielectric (delay)
types.
1-23
CHAPTER 2
FIRE CONTROL RADAR SYSTEMS
LEARNING OBJECTIVES
Upon completing this chapter, you should be able to do the following:
1. Identify and describe search radar systems associated with fire control radar.
2. Identify and describe missile and gun fire control radar systems.
3. Identify and describe other related sensor systems associated with fire control radar.
4. Describe the detect-to-engage scenario.
5. Describe the fire control problem in relationship to the detect to engage scenario.
INTRODUCTION
SEARCH RADAR
In the preceding chapter, you read about the basic
principles of radar operation. You also read about the
basic components of a radar system and their
relationship to each other. This chapter deals with
specific radar systems and terms associated with those
systems. You must understand those terms to get the
maximum benefit from the information contained in
this chapter. If you don’t have a good understanding of
radar operation and theory, we suggest that you review
the following Navy Electricity and Electronics
Training Series (NEETS) modules: Microwave
Principles, Module 11, NAVEDTRA 172-11-00-87,
and Radar Principles, Module 18, NAVEDTRA
172-18-00-84. We also suggest that you refer to the
Functional Description section in your own technical
manuals for the specific operation of your radar
equipment.
You may think the function of Fire Control radar is
to lock on to and identify a specific hostile target in
order to direct a weapon to destroy it. That is the
function of most FC radars. However, most FC radars
use a narrow beam to perform their function. This
makes using FC radar for locating a target impractical,
since a narrow beam can easily miss targets. Locating
targets requires using a radar with a wide beam. Search
radar has such a beam. Search radar provides
long-range (200 nautical miles or more), 360-degree
coverage. It can determine a target’s range, bearing,
and elevation, and can then hand over that information
to the more accurate narrow-beamed FC radar. Some
Fire Control systems have built-in search and track
radar; others rely on completely separate search radar.
In this section, we will cover the separate search radars
you will see in the surface Navy. These are the
AN/SPS-52C and the AN/SPS-48 series search radars.
The Fire Controlman rating deals with a large
number of different radar systems, but you will
probably be trained in only one or two of these systems.
To help you develop a broad understanding of Fire
Control radar, we will first discuss the Fire Control
radars and sensors used in the Fleet today. We will do
t h i s b y c a t eg o r y : s e a r c h r a d a r, m i s s i l e
direction/illumination radar, multi-function radar, and
optronics systems. Then we will give you an overview
of upcoming developments in radar.
AN/SPS-52 SEARCH RADAR
The AN/SPS-52C is a ship mounted, air search,
three-dimensional radar system that provides target
position data in range, bearing, and elevation. It
produces three-dimensional coverage from a single
antenna by using electronic scanning in elevation and
mechanical rotation in azimuth. The 52C uses the
AN/SPA-72B antenna as did the earlier AN/SPS-52
systems, but has completely different below-the-decks
2-1
electronics. Because of this, the 52C has significant
improvements over earlier versions of the 52 radar in
the areas of detection, reliability, and maintenance.
characteristics of the various ship’s radars can be
integrated, resulting in more accurate and quicker
detection of threats. This is part of a program for
non-AEGIS class ships called New Threat Upgrade
(NTU).
The antenna assembly (fig. 2-1) is a planar array,
tilted back at an angle of 25 degrees. This 25-degree tilt
allows the antenna to provide high-elevation coverage.
The array is a collection of rows of slotted waveguides
and is fed RF from a feed system running the length of
one side of the total array assembly. This antenna scans
in the vertical plane by transmitting different
frequencies, as selected by a digital computer.
The AN/SPS-52C radar is presently found on the
WASP (LHD) class and the TARAWA (LHA) class
amphibious assault ships. It will eventually be replaced
by the AN/SPS-48E.
AN/SPS-48 RADAR
The AN/SPS-52C radar has four modes of
operation: high angle, long range, high data rate, and
MTI (Moving Target Indicator). The operator selects
the appropriate mode, depending on the threat type and
environment. The primary mode is high angle. In this
mode, the radar provides coverage to a range of
approximately 180 miles and an elevation of
approximately 45 degrees. In the long-range mode,
t h e r a d a r p r ov i d e s c ove r a g e t o a r a n g e o f
approximately 300 miles and an elevation of
approximately 13 degrees. The high data rate mode
provides a range of approximately 110 miles and an
elevation of approximately 45 degrees. This mode is
used because of its unique ability to acquire pop-up
and close-in targets quickly. The MTI mode is useful in
a high-clutter environment (such as weather in extreme
sea-state conditions) where targets are normally hard
to locate. Coverage is about 70 miles and up to an
elevation of 38 degrees.
The AN/SPS-48 radar is a complete system
upgrade of the AN/SPS-52C including all component
elements — transmitter, receiver, computer (radar and
automatic detection and tracking), frequency
synthesizer and height display indicator. Figure 2-2
shows an antenna for the SPS-48 radar on the USS
Boxer LHD-4 (see arrow).
The SPS-48 radar is a long-range, threedimensional, air-search radar system that provides
contact range, bearing, and height information to be
displayed on consoles and workstations. It does
this by using a frequency-scanning antenna,
which emits a range of different frequencies in
the E/F band. The SPS-48 radar has three power
modes: high, medium, and low.
An upgrade was needed because the 52C radar’s
single elevation beam could not dwell long enough in
any particular direction. To solve this problem, the 48
series uses a process that stacks nine beams (a train of
nine pulses at different frequencies) into a
pulse-group. The nine beams simultaneously scan a
5-degree elevation area, allowing the stack to cover 45
degrees of elevation.
The 52C radar is used with the SYS-1/SYS-2 radar
system. The SYS-1/SYS-2 system coordinates all
radar sensors on a ship into a single system. It does this
by using a processor designed around integrated
automatic detection-and-tracking (IADT). The
advantage of using such a system is that the unique
Two versions of the SPS-48 are currently in use:
the 48C and the latest version, the 48E. Maximum
elevation has increased somewhat, 65 degrees versus
45 degrees for the 52C. The “E” version has twice the
radiated power of the “48C”, developed by reducing
the sidelobes and increasing the peak power. Receiver
sensitivity is increased and the 48E has a four-stage
solid state transmitter. The main operating modes are:
• EAC (Equal Angle Coverage)—The radar’s
energy is concentrated at a low angle.
• MEM (Maximum Energy Management)—Both
high and medium power are regulated.
• AEM (Adaptive Energy Management)—Allows
the radar to be adapted to a priority target radar
Figure 2-1.—AN/SPS-52 radar antenna.
2-2
Figure 2-2.—SPS-48 series radar on USS Boxer, a WASP class
amphibious assault ship.
cross section and a potential jamming
environment.
ship’s gyro system provides the radar set with this
pitch and roll data.
• LOW-E (Low Elevation)—Gives priority to the
lower beam groups and transmits them as a
Doppler wave.
The AN/SPS-48 radar works with other onboard
radar sensors through the SYS-1/SYS-2, as did the
AN/SPS-52C. Search data from the AN/SPS-48 radar
is sent to multiple weapon systems. These include the
Mk 91 Fire Control System for the SEASPARROW
missile system, the Mk 95 radar, the Mk 23 Target
Acquisition System, the Close-In Weapon System, and
the Rolling Airframe Missile (RAM) System.
The radar can also transmit as a single steerable
beam group or it can burn through jamming using a
chirp pulse.
Radar video, converted to a digital format, is
displayed on consoles to allow operators to perform
manual radar search, detection and tracking functions.
True bearing indications appear when the track
position is displayed in relation to true north, rather
than to ownship.
The AN/SPS-48 search radar is found onboard
NIMITZ (CVN-68) (figure 2-3), KITTY HAWK
(CV-63), and ENTERPRISE (CVN-65) class carriers,
BLUE RIDGE (LCC) class amphibious command
ships, and WASP (LHD) and TARAWA (LHA) class
amphibious assault ships.
Variation in frequency tends to make this radar
more resistant to jamming than if it were operated at a
fixed frequency. This provides a solution to the blind
speed problem (“blind speed” is the speed a target
travels that is too fast for the radar to track it) in
systems. Frequency scanning imposes some
limitations because a large portion of the available
frequency band is used for scanning rather than to
increase the resolution of targets. It also requires that
the receiver bandwidth be extremely wide or that the
receiver be capable of shifting the bandwidth center
with the transmitted frequency.
Q1. What operational characteristic makes the
AN/SPS-48 series radar resistant to jamming?
MISSILE AND GUN FIRE CONTROL
RADAR
Although you may be involved in the operation of
search radar, the majority of your work will be with
radar systems used to control the direction and fire of
gun and missile systems. These radar systems are
normally part of a larger system. They are called Gun
Fire Control Systems (GFCS) or Missile Fire Control
Systems (MFCS). Some systems may be able to
control the fire of either guns or missiles. These are
The radar provides accurate height data by
factoring in the effects of pitch and roll of the ship and
changing the transmitted frequency accordingly. The
2-3
Figure 2-3.—USS Nimitz (CVN-68).
simply called Fire Control Systems (FCS). This
section will look at the radar associated with these gun
and missile fire control systems.
Mk 99 Missile Fire Control System (MFCS) and the
Mk 86 Gun Fire Control System (GFCS) or the Mk 34
GWS (Gun Weapon System). We will discuss each of
these systems briefly as they relate to their associated
radar systems.
MK 7 AEGIS FIRE CONTROL SYSTEM
RADAR
AN/SPY-1 Radar
The Mk 7 AEGIS Weapon System is installed on
ARLEIGH BURKE class destroyers (fig. 2-4) and
TICONDEROGA class cruisers (fig. 2-5). The Mk 7
AEGIS system contains the SPY-1 radar system, the
The latest technology in multi-function radar is
found in the AN/SPY-1 series on TICONDEROGA
class cruisers and ARLEIGH BURKE class
Figure 2-4.—AEGIS class destroyer DDG-60 USS Paul Hamilton.
2-4
Figure 2-5.—USS Ticonderoga CG-47.
AEGIS system is an advanced, automatic detect and
track, multi-functional phased-array radar, the
AN/SPY-1. This high-powered (four-megawatt) radar
can perform search, track, and missile guidance
functions simultaneously, with a capability of over 100
targets. The first system was installed on the test ship,
USS Norton Sound (AVM-1) in 1973. Figure 2-6
shows the weapons and sensors on an AEGIS class
cruiser.
destroyers. Ships that do not use the AN/SPY-1 are
being upgraded to a system known as Ship
Self-Defense System (SSDS). We will discuss SSDS
in another section.
For more than four decades, the U.S. Navy has
developed systems to protect itself from surface and air
attacks. After the end of World War II, several
generations of anti-ship missiles emerged as threats to
the fleet. The first anti-ship missile to sink a combatant
was a Soviet-built missile that sank an Israeli destroyer
in October 1967. This threat was reconfirmed in April
1988 when two Iranian surface combatants fired on
U.S. Navy ships and aircraft in the Persian Gulf. The
resulting exchange of anti-ship missiles led to the
destruction of an Iranian frigate and a corvette by
U.S.-built Harpoon missiles.
The system’s core is a computer-based command
and decision element. This interface enables the
AEGIS combat system to operate simultaneously in
a n t i - a i r wa r fa r e , a n t i - s u r fa c e wa r fa r e , a n d
anti-submarine warfare.
The AN/SPY-1 series radar system works with
two fire control systems on AEGIS class ships: the Mk
99 Missile Fire Control System and the Mk 86 Gun
Fire Control System (part of the Mk 34 Gun Weapon
System). The Mk 86 GFCS is also found on
SPRUANCE class destroyers and works with the Mk
91 Missile Fire Control System. We will discuss the
Mk 91 MFCS in a later section.
The U.S. Navy’s defense against this threat relied
on a strategy of gun and missile coordinated defense.
Guns were supplemented in the late fifties by the first
generation of guided missiles in ships and aircraft. By
the late sixties, although these missiles continued to
perform well, there was still a need to improve missile
technology in order to match the ever-changing threat.
To counter the newer enemy missile threat, the
Advanced Surface Missile System (ASMS) was
developed. ASMS was re-named AEGIS (after the
mythological shield of Zeus) in December 1969.
Mk 99 Missile Fire Control System
The Mk 99 MFCS controls the loading and arming
of the selected weapon, launches the weapon, and
provides terminal guidance for AAW (Anti-Air
Warfare) missiles. It also controls the target
illumination for the terminal guidance of SM-2
The AEGIS system was designed as a total weapon
system, from “detection” to “kill”. The heart of the
2-5
Figure 2-6.—Radar and weapon systems on an AEGIS class cruiser.
Anti-Air missiles (fig. 2-7). The radar system
associated with the Mk 99 MFCS is the missile
illuminator AN/SPG-62.
Mk 86. The Mk 86 GFCS controls the fire of the Mk 45
5-inch gun.
MK 86 GUN FIRE CONTROL SYSTEM
AN/SPG-62 RADAR.—The AN/SPG-62 is I/JBand fire control radar. The SPY-1 radar system
detects and tracks targets and then points the SPG-62
toward the target, which in turn provides illumination
for the terminal guidance of SM-2 missiles. Refer to
chapter 1 for discussion on the different phases of
missile guidance and the way radar is used for missile
guidance. Remember that in order to track a target you
need a very narrow beam of RF energy. The narrower
the beam, the more accurately you can tell if you have
one target or multiple targets (this is called radar
resolution). This narrow beam radar is normally a
second radar that works with a primary search or track
radar. The AN/SPG-62 illuminating radar works as a
second radar with the AN/SPY-1 series radar. See
figure 2-6 for the location of AN/SPG-62 on an AEGIS
cruiser.
The Mk 86 Gun Fire Control System (GFCS)
provides ships of destroyer size and larger with an
economical, versatile, lightweight, gun and missile fire
control system that is effective against surface and air
targets.
The Mk 86 Gun Fire Control System (GFCS) is the
central sub-element of the Mk 34 Gun Weapons
System (GWS) on AEGIS class ships. It controls the
ship’s forward and aft 5"/54 caliber Mk 45 gun mounts
(fig. 2-8) and can engage up to two targets
simultaneously. The SPQ-9 series and Mk 23 TAS
(Target Acquisition System) work together to provide
control for Naval Gun Fire Support (NGFS),
Submarine Warfare (SUW) and Anti-Air Warfare
(AW) gun engagements. The Mk 86 GFCS also uses a
Remote Optical Sighting system. This is a separate TV
camera with a telephoto zoom lens mounted on the
mast and each of the illuminating radars. The optical
sighting system is known as ROS on the SPRUANCE
class destroyers and is mounted on the SPG-60
illumination radar. The Mk 34 GWS on AEGIS class
destroyers and cruisers uses the Mk 46 Mod 0 Optical
Sight System on the SPG-62 illuminators.
In addition to the Mk 99 MFCS, the AEGIS SPY-1
series radar works with the Gun Fire Control System
The Mk 86 GFCS is the controlling element, where
loading and firing orders originate. After an operator
selects the GFCS mode, the system calculates ballistic
gun orders. These orders can be modified to correct for
environmental effects on ballistics. The GFCS
conducts direct firing attacks against surface radar and
optically tracked targets, as well as indirect firing
during Naval Gun Fire Support (NGFS).
Figure 2-7.—SM-2 ER Anti-Air missile on launcher.
2-6
Figure 2-8.—A 5”/54 Mk 45 gun mount.
See figure 2-10 for a list of weapon systems and
their sensors related to the Mk 86 GFCS on a
SPRUANCE class destroyer.
signals indicating antenna relative azimuth, Azimuth
Reference Pulses (ARP), and Azimuth Change Pulse
(ACP). The radar will maintain its capabilities in the
presence of clutter from the sea, rain, land, discrete
objects, birds, chaff, and jamming.
AN/SPQ-9 Radar
The AN/SPQ-9B has three modes of operation: air,
surface, and beacon. The air and surface modes have a
submode for Combat Systems training. The
AN/SPQ-9B complements high-altitude surveillance
radar in detecting missiles approaching just above the
sea surface. The system emits a one-degree beam that,
at a range of approximately 10 nautical miles, can
detect missiles at altitudes up to 500 feet. Since the
beamwidth expands over distance, the maximum
altitude will increase at greater ranges.
The AN/SPQ-9 Surface Surveillance and Tracking
Radar, developed by Northrop Grumman Norden
Systems, Melville, NY, is a track-while-scan radar
used with the Mk-86 Gunfire Control system on
surface combatants. Since it is a typical fire control
radar, we will discussed it in more detail to help you
understand the basic function of fire control radar.
The AN/SPQ-9B detects sea-skimming missiles at
t h e h o r i z o n , eve n i n h e av y c l u t t e r, w h i l e
simultaneously providing detection and tracking of
s u r fa c e t a rg e t s a n d b e a c o n r e s p o n s e s . T h e
AN/SPQ-9B is available as a stand-alone radar or as a
replacement for the AN/SPQ-9 in the Mk 86 Gun Fire
Control System, which will be integrated into the Mk 1
Ship Self Defense System (SSDS).
The air mode uses the Pulse-Doppler radar for
detecting air targets. When the AN/SPQ-9B radar
detects an air target and initiates a track, it will
determine the target’s position, speed, and heading.
The air mode has a sector function called the Anti-Ship
Missile Defense (ASMD). When the radar is radiating,
the air mode is enabled continuously.
The Radar Set AN/SPQ-9B is a high resolution,
X-band narrow beam radar that provides both air and
surface tracking information to standard plan position
indicator (PPI) consoles. The AN/SPQ-9B scans the
air and surface space near the horizon over 360 degrees
in azimuth at 30 revolutions per minute (RPM).
Real-time signal and data processing permit detection,
acquisition, and simultaneous tracking of multiple
targets. The AN/SPQ-9B provides raw and clear plot
(processed) surface video, processed radar air
synthetic video, gate video, beacon video synchro
The surface mode generates a separate surface
frequency and an independent pulse with a pulse
repetition interval (PRI) associated with a range of
40,000 yds. In the surface mode, the AN/SPQ-9B radar
has 360-degree scan coverage for surface targets. The
radar displays raw and clear plot video, has a submode
called Surface-Moving Target Indicator (MTI), and
operates concurrently with the air mode. While the
radar is in the radiate state, the surface mode is enabled
continuously.
2-7
• LPD-17 SAN ANTONIO class amphibious
ships
The beacon mode generates a separate beacon
frequency and an independent pulse with a PRI having
a range of 40,000 yds. The AN/SPQ-9B radar has
360-degree scan coverage for beacon targets. The
received beacon video is sent to the console for display
and distribution, while beacon track data is sent to the
computer for processing. The AN/SPQ-9B beacon
mode operates at the same time as the air and surface
modes.
• DD-963 SPRUANCE class destroyers (figure
2-10)
• DDG-51 destroyers (figure 2-4)
The AN/SPQ-9 series radar also works with the
SPY-1 series radar. SPQ-9 radar helps to control a
number of weapons which include: SM-1/SM-2
missiles and the Mk 45 5”/54 gun.
The ASMD Sector function allows the air mode to
provide quick response detection of low-flying
high-threat targets. Through this function, the radar
automatically detects, tracks, and reports any targets
entering the ASMD sector that require a reaction time
of less than 30 seconds. The operator can select an
ASMD azimuth sector width between five and 360
degrees and a range of up to 20 NMI. The ASMD sector
function operates together with the air, surface, and
beacon modes.
Mk 23 Target Acquisition System (TAS)
The Mk 23 Target Acquisition System (TAS) is a
detection, tracking, identification, threat evaluation,
and weapon assignment system. It is used against
high-speed, small cross-section targets that approach
the ship from over the horizon at very low altitudes or
from very high altitudes at near vertical angles. The
TAS integrates a medium-range, two-dimensional,
air-search radar subsystem, an IFF subsystem, a
display subsystem, and a computer subsystem. This
allows TAS to provide automatic or manual target
detection and tracking, target identification, threat
evaluation, and weapon assignment capabilities for
engagement of air tracks. The Mk 23 TAS automatic
detection and tracking radar is also an element of the
Mk 91 Missile Fire Control system and is used on
SPRUANCE class destroyers, carriers, LHDs, LHAs,
and the LPD-17 class amphibious assault ships. The
Mk 91 MFCS and TAS control the SEASPARROW
missile as their primary weapon. Figure 2-9 shows a
Mk 29 box launcher for SEASPARROW missiles.
The Surface-MTI Submode allows the surface
mode to cancel non-moving targets. The Surface-MTI
azimuth sector width is operator selectable between a
bearing width of five and 360 degrees, with the
AN/SPQ-9B automatically displaying any targets with
a relative speed exceeding 10 knots. The AN/SPQ-9B
R a d a r S u r fa c e - M T I s u b m o d e w i l l o p e r a t e
concurrently with the air, surface, and beacon modes.
The AN/SPQ-9B is installed on ships and aircraft
carriers in the following classes:
• CG-47 TICONDEROGA class cruisers (figure
2-5)
• LHD-1 amphibious ships (figure 2-2)
Figure 2-9.—Mk 29 box launcher for SEASPARROW missiles.
2-8
MK 91 FIRE CONTROL SYSTEM
MK 92 FIRE CONTROL SYSTEM RADAR
The Mk 91 NATO SEASPARROW Guided
Missile Fire Control System (GMFCS) integrates the
Mk 157 NATO SEASPARROW Surface Missile
System (NSSMS) into the Ship Self Defense System
(SSDS) to provide an additional layer of ship missile
defense. In this system, the Firing Officer Console and
Radar Set Consoles are combined into a single
Advanced Display System Console (AN/UYQ 70); the
Signal Data Processor is modified; the Mk 157
Computer Signal Data Converter and the System
Evaluation and Trainer (SEAT) are eliminated; and the
microprocessor circuitry within the SSDS electronics
is upgraded. This eliminates the limited input-output
channel and computer processing deficiencies resident
in the older Mk 57 NSSMS. The radar associated with
the Mk 91 Fire Control System includes the Mk 95
illuminator, Mk 23 Target Acquisitioning System, and
the AN/SPQ-9 series radar.
The Mk 92 Fire Control System (FCS) provides
FFG-7 class frigates (Figure 2-11) and other surface
combatants with a fast reaction, high firepower,
all-weather weapons control system for use against air
and surface targets. The Mark 92’s surface and air
surveillance capability gives highly accurate gun and
missile control against air and surface targets.
The Mark 92 fire control system, an American
version of the WM-25 system designed in the
Netherlands, was approved for service use in 1975.
Introduction to the fleet and follow-on test and
evaluation began in 1978. In 1981, an aggressive
program to improve performance and reliability of the
Mk 92 fire control system in clutter and electronic
counter-measure environments was launched, with an
at-sea evaluation aboard the USS Estocin completed in
The Mk 95 illuminator is used exclusively with the
NATO SEASPARROW GMFCS. It is an X-band
tracker-illuminator on a Mk 78 director and works with
the Mk 23 TAS. The Mk 91 Fire Control System and its
associated radar systems are found on Spruance class
destroyers, carriers, LHDs, AOEs, AORs, and
TARAWA class amphibious assault ships.
See figure 2-10 for the various weapons systems
and radar associated with the Mk 86 and Mk 91 fire
control systems on a SPRUANCE class destroyer.
Figure 2-11.—FFG-57 PERRY class frigate.
Figure 2-10.—Weapons and sensors on SPRUANCE class destroyer.
2-9
Figure 2-12.—Mk 75 Naval Gun system.
1986. Following the evaluation, the upgraded system,
identified as Mk 92 Mod 6 was installed in USS
Ingraham (FFG-61). The Mk 92 Mod 6 will replace the
Mod 2 systems in the fleet.
antiair and antisurface missile and gun systems
control, engaging up to four targets simultaneously.
The Mk 92 “track-while-scan” radar uses the
Combined Antenna System (CAS), which houses a
search antenna and a tracker antenna inside a single
egg-shaped radome (fig.2-14). A Separate Target
Illumination Radar (STIR) (fig. 2-14) designed for the
PERRY class Mk 92 FCS application provides a large
diameter antenna for target illumination at ranges
beyond CAS capabilities.
The Mk 92 Fire Control System (FCS) is deployed
on board FFG-7 PERRY class ships in conjunction
with the Mk 75 Naval Gun (fig. 2-12) and the Mk 13
Guided Missile Launching System (fig. 2-13). The Mk
92 FCS integrates target detection with multichannel
A Mod 1 version of the Mk 92 system is installed
on the US Coast Guard’s WMEC (Medium-Endurance
Cutter, figure 2-15) and its WHEC (High-Endurance
Cutter). This version can track one air or surface target
using the monopulse tracker and two surface or shore
targets using track-while-scan data from CAS. Using
STIR, the Mod 2 system on FFG-7 class frigates can
track an additional air or surface target.
CLOSE-IN WEAPON SYSTEM RADAR
The Mk 15 Phalanx Close-In Weapon System
(CIWS — pronounced “sea-whiz”) is a stand-alone,
quick-reaction time defense system that provides final
defense against incoming air targets. CIWS will
automatically engage anti-ship missiles and
high-speed, low-level aircraft that penetrate the ship’s
primary defenses. As a stand-alone weapon system,
CIWS automatically searches for, detects, tracks,
evaluates for threat, fires at, and assesses kills of
targets. A manual override function allows the operator
to disengage a target, if necessary.
The search and track radar antennas are enclosed
in a radome mounted on top of the gun assembly (see
Figure 2-13.—Mk 13 Guided Missile Launcher system.
2-10
Figure 2-14.—Mk 92 Fire Control System on PERRY class frigate.
Figure 2-15.—WMEC-910 Coast Guard Cutter Thetis with Mk 92 CAS.
search antenna. Limitations of elevation in Block 0
lead to the next upgrade, Block 1. Block 1 provided
improved elevation coverage and search sensitivity by
using a phased-array antenna. A minor upgrade to
Block 1, known as Block 1A, improved the processing
power of the computer by incorporating a new
high-order language. This upgrade gave CIWS the
ability to (1) track maneuvering targets and (2) work
with multiple weapons coordination. The next
upgrade, Block 1B, enabled CIWS to engage surface
targets. This upgrade is known as the Phalanx Surface
Mode (PSUM). A special radar, Forward-Looking
Infrared Radar (FLIR), was added to CIWS to detect
small surface targets (i.e., patrol/torpedo boats) and
low, slow, or hovering aircraft (i.e., helicopters). This
radar is mounted on the side of the radome structure.
FLIR can also help the radar system engage anti-ship
cruise missiles. To detect targets day or night, CIWS
Block 1B uses a thermal imager and advanced
electro-optic angle tracking.
figure 2-16). All associated electronics for radar
operations are enclosed within either the radome or the
Electronics Enclosure (called the ELX). CIWS is
operated remotely from either a Local Control Panel
(LCP) or the Remote Control Panel (RCP) located in
the Combat Information Center (CIC). It has two
primary modes of operation: automatic and manual. In
the automatic mode, the computer program determines
the threat target, automatically engages the target, and
performs the search-to-kill determination on its own.
In the manual mode, the operator fires the gun after
CIWS has identified the target as a threat and has given
a “recommend fire” indication.
CIWS was developed in the late 1970’s to defend
against anti-ship cruise missiles. However, as the
sophistication of cruise missiles increased, so did the
sophistication of CIWS. Major changes to CIWS are
referred to as “Block” upgrades. The first upgrade,
known as “Block 0”, incorporated a standard rotating
2-11
Figure 2-17.—Missile launch from an AEGIS class cruiser.
detect sequence through the engage sequence. This
provides a quick response, multi-target engagement
capability against anti-ship cruise missiles.
Figure 2-16. —CIWS radome with search and track radar.
SHIP SELF-DEFENSE SYSTEM (SSDS)
The entire combat system, including the sensors
and weapons, is referred to as Quick Reaction Combat
Capability (QRCC), with SSDS as the integrating
element. Although SSDS broadens the ship’s
defensive capability, it is not intended to improve the
performance of any sensor or weapon beyond its
stand-alone performance. The primary advantage
SSDS brings to the combat systems suite is the ability
to coordinate both hard kill (gun and missile systems)
and soft kill (decoys such as chaff) systems and to use
them to their optimum tactical advantage.
The principal air threat to US naval surface ships is
a variety of highly capable anti-ship cruise missiles
(ASCMs)(figure 2-17). These include subsonic (Mach
0.9) and supersonic (Mach 2+), and low altitude
ASCMs. Detection, tracking, assessment, and
engagement decisions must be made rapidly to defend
against these threats, since the time from when an
ASCM is initially detected until it is engaged is less
than a minute. SSDS is designed to accomplish these
defensive actions.
The following systems represent the SSDS
interfaces for a non-AEGIS ship:
SSDS, consisting of software and commercial
off-the-shelf (COTS) hardware, integrates and
coordinates all of the existing sensors and weapons
systems aboard a non-AEGIS ship to provide Quick
Reaction Combat Capability (QRCC). (It will
eventually be installed on board most classes of
non-AEGIS ships.) SSDS (fig. 2-18), by providing a
Local Area Network (LAN), LAN access units
(LAUs), special computer programs, and operator
stations, automates the defense process, from the
• AN/Air Search Radar
• AN/Surface Search Radar
• AN/Electronic Warfare System
• Centralized Identification Friend or Foe (CIFF)
• Rolling Airframe Missile (RAM)
2-12
SSDS AUTOMATES THE DETECT TO ENGAGE SEQUENCE
DETECT
ENGAGE
QRCC
ECM
SSDS
CONTROL
FIBER-OPTIC LOCAL AREA NETWORK (LAN)
Figure 2-18. —Ship Self-Defense System.
• Phalanx Close-in Weapon System (CIWS)
deploy chaff or a decoy, or provide some combination
of these.
• Mk 36 Decoy Launching System (DLS)
Q2. What classes of ship use the AN/SPY-1 radar
system?
SSDS options range from use as a tactical decision
aid (up to the point of recommending when to engage
with specific systems) to use as an automatic weapon
system. SSDS will correlate target detections from
individual radars, the electronic support measures
(ESM) system, and the identification-friend or foe
(IFF) system, combining these to build composite
tracks on targets while identifying and prioritizing
threats. Similarly, SSDS will expedite the assignment
of weapons for threat engagement. It will provide a
“recommend engage” display for operators or, if in
automatic mode, will fire the weapons, transmit ECM,
Q3. In the Mk 99 MFCS, the terminal guidance phase
of a SM-2 missile is controlled by what
illuminating radar?
Q4. Name the three modes of operation of the
AN/SPQ-9 radar?
Q5. The NATO SEASPARROW missile is controlled
by what fire control system?
Q6. What class of ship uses the Combined Antenna
System (CAS) and the Separate Target
Illumination Radar (STIR)?
2-13
to do more with less. We mention some of these
developments, related to radar and sensors, below.
Q7. What type of ships, in general, are being
upgraded with the Ship Self-Defense System
(SSDS)?
HIGH FREQUENCY SURFACE WAVE
RADAR
OPTRONICS SYSTEMS
High frequency surface wave radar is used to
detect low-altitude missiles beyond the ship’s horizon.
The transmitting antennas are meandering-wave type
units and are mounted on either side of the ship, near
the bridge. The receivers are separate deck-edge or
superstructure units. This radar uses an FMCW
(Frequency Modulated-Continuous Wave) transmitter
with a 50% duty cycle, with co-located transmit and
receive antennas.
As you have seen, the majority of sensor systems
you will work with are of the RF type. That is, RF
energy is transmitted via a complex system of
components to detect and destroy a target. There are
also other sensors used in today’s Navy that use a
different method of locating targets and helping in the
direction of weapons. These systems use light or heat
as a source for target detection. They are described as
“Optronic” systems because they use light frequency
rather than RF energy as a detecting element and a
system of optical lenses for focusing a light source. An
example of this type of system used in the Navy today
is the Thermal Imaging Sensor System (TISS). It is
representative of other similar optronics systems in use
today.
MULTI-FUNCTION RADAR
The Multi-Function radar is a development for the
DD-21 Land Attack destroyer that provides ship
self-defense and local area defense against air and
missile threats. The new Multi-Function radar (MFR)
will greatly enhance ship defense capability against
modern air and missile threats in the littoral
environment (areas close to shoreline). This system is
based on solid-state, active-array radar technology that
will provide search, detect, track, and weapon control
functions while dramatically reducing manning and
life-cycle costs associated with the multiple systems
that perform these functions today. The MFR will be
complemented by a new Volume Search Radar (VSR),
which will provide timely cueing to MFR at long
ranges and above the horizon. The VSR will be
acquired as part of the DD-21 total ship system. (See
Figure 2-19)
THERMAL IMAGING SENSOR SYSTEM
(TISS)
The Thermal Imaging Sensor System (TISS) is a
shipboard electro-optical system that consists of a
low-light television camera and an eye-safe laser
rangefinder. The TISS director is designed to be mast
mounted. The control console can be mounted in CIC
or in the pilothouse. In addition to providing surface
and air target data to combat systems, the TISS can also
be used to detect mines and to provide good night
identification and detection capabilities.
TISS was originally tested on board the USS
Ticonderoga (CG-47) and later installed on the USS
Vicksburg (CG-69) for her deployment to the Middle
East in April 1997. TISS will initially be installed as a
stand-alone system on deploying ships. As more units
are completed, permanent installation and integration
into the combat systems will become standard.
Systems that use TISS are the Mk 86 Gun Fire Control
System, CIWS, SSDS, and RAM.
INFRARED SEARCH AND TRACK (IRST)
The Infrared Search and Track (IRST) system is an
integrated sensor designed to detect and report
low-flying antiship cruise missiles by detecting their
thermal heat plume or heat signature. IRST will
continually scan the horizon and report any contacts to
the ship’s combat information center for tracking and
engagement. The scanner is designed to search several
degrees above and below the horizon but can be slewed
manually to search for higher flying targets. IRST is a
passive system providing bearing, elevation angle, and
thermal intensity of a target. The system consists of a
mast-mounted and stabilized scanner, below decks
electronics, and a UYQ-70 operator’s console.
Q8. What type of system is TISS?
UPCOMING DEVELOPMENTS IN
RADAR
To keep pace with the approaching 21st century
needs for multi-mission surface warships, the Navy is
continually developing new technology that allows it
2-14
Figure 2-19.—Artist’s conception of DD-21 land attack destroyer.
DETECT TO ENGAGE SEQUENCE FOR
FIRE CONTROL
Dozens of displays indicate the activity of ships and
aircraft near the Battle Group (fig. 2-20). As the TAO,
you are responsible for the proper employment of the
ship’s weapons systems in the absence of the
commanding officer. The time is 0200. You are in
charge of a multi-million dollar weapon system and
responsible for the lives and welfare of your
shipmates.
This chapter has covered the radar systems you
will see as an FC in the Fleet today. You have been
given a brief overview of the radar systems and their
functions and uses. You have also learned the
associated weapon systems and ship types associated
with each radar system. Now that you have an
understanding of these radar systems, you need to
know how these systems are used in an actual combat
scenario. The following section gives you an
imaginary scenario of what might happen if you were
to detect an enemy target, from beginning to end.
The relative quiet is shattered by an alarm on your
Electronic Warfare (EW) equipment indicating the
initial detection and identification of a possible
incoming threat by your Electronic Support Measures
(ESM) equipment. The wideband ESM receiver
detects an electromagnetic emission on a bearing in the
direction of Nation Q. Almost instantaneously the
ESM equipment interprets the emitter’s parameters
and compares them with radar parameters stored in its
memory. The information and a symbol indicating the
emitter’s approximate line of bearing from your ship
are presented on a display screen. You notify the
commanding officer of this development. Meanwhile,
the information is transmitted to the rest of the Battle
Group via radio data links.
THE DETECT-TO-ENGAGE SEQUENCE
The international situation has deteriorated and the
United States and Nation Q have suspended diplomatic
relations. The ruler of Nation Q has threatened to
annex the smaller countries bordering Nation Q and
has threatened hostilities toward any country that tries
to stop him. You are assigned to a guided missile
cruiser that is a member of Battle Group Bravo,
currently stationed approximately 300 nautical miles
off the coast of Nation Q. The battle group commander
has placed the Battle Group on alert by specifying the
Warning Status as YELLOW in all warfare areas,
meaning that hostilities are probable.
Moments later, in another section of CIC, the
ship’s long-range two-dimensional air search radar is
just beginning to pick up a faint return at its maximum
range. The information from the air search radar
coupled with the line of bearing from your ESM allows
you to localize the contact and determine an accurate
range and bearing. Information continues to arrive, as
the ESM equipment classifies the J-band emission as
You are standing watch as the Tactical Action
Officer (TAO) in the Combat Information Center
(CIC), the nerve center for the ship’s weapons systems.
2-15
Figure 2-20. —Display consoles in the Combat Information Center (CIC).
According to the Rules of Engagement (ROE) in
effect, you have determined hostile intent on the part of
the target and should defend the ship against imminent
attack. You inform your CIC team of your intentions,
and select a weapon, in this case a surface to air missile
(fig. 2-21), to engage the target. You also inform the
Anti-Air Warfare Commander of the indications of
hostile intent, and he places you and the other ships in
Air Warning Red, “attack in progress”.
belonging to a Nation Q attack aircraft capable of
carrying anti-ship cruise missiles.
The contact continues inbound, headed toward the
Battle Group. Within minutes, it is within range of your
ship’s three-dimensional search and track radar. The
contact’s bearing, range, and altitude are plotted to
give an accurate course and speed. The range
resolution of the pulse-compressed radar allows you to
determine that the target is probably just one aircraft.
You continue to track the contact as you ponder your
next move.
As the target closes to the maximum range of your
weapon system, the fire control or tactical computer
program, using target course and speed computes a
predicted intercept point (PIP) inside the missile
engagement envelope. This information and the report
that the weapon system has locked-on the target is
reported to you. You authorize “batteries release” and
As the aircraft approaches the outer edge of its
air-launched cruise missile’s (ALCM) range, the ESM
operator reports that aircraft’s radar sweep has
changed from a search pattern to a single target track
mode. This indicates imminent launch of a missile.
Figure 2-21. —Surface-to-Air missile.
2-16
Figure 2-22.—Missile launch.
the missile is launched toward the PIP (fig. 2-22). As
the missile speeds towards its target at Mach 2+, the
ship’s sensors continue to track both the aircraft and
the missile. Guidance commands are sent to the missile
to keep it on course.
On board the enemy aircraft, the pilot is preparing
to launch an ALCM when his ESM equipment
indicates he is being engaged (figure 2-23). This
warning comes with but precious few seconds, as the
missile enters the terminal phase of its guidance. In a
Figure 2-23.—Enemy aircraft.
2-17
desperate attempt to break the radar lock, the pilot uses
evasive maneuvering. It’s too late though. As the
missile approaches its lethal “kill radius,” the
proximity fuze on the missile’s warhead detonates the
missile’s explosive charge, sending fragments out in
every direction, destroying or neutralizing the target
(figure 2-24). This information is confirmed by your
ship’s sensors. The radar continues to track that target
as it falls into the sea and the ESM equipment goes
silent.
sea, or even beneath the sea (figure 2-25). It may be
manned or unmanned, guided or unguided,
maneuverable or in a fixed trajectory. It may travel at
speeds that range from a few knots to several times the
speed of sound.
THE FIRE CONTROL PROBLEM
To accomplish one specific function, a complex
array of subsystems may be interconnected by
computers and data communication links. This
interconnecting allows the array to perform several
f u n c t i o n s o r t o e n g a g e n u m e r o u s t a rg e t s
simultaneously. Although each subsystem may be
specifically designed to solve a particular part of the
fire control problem, having these components operate
in concert that allows the whole system to achieve its
ultimate goal — the neutralization of the target.
The term weapons system is a generalization
encompassing a broad spectrum of components and
subsystems. These components range from simple
devices operated manually by a single person to
complex devices operated by computers.
The above scenario is not something out of a war
novel, but rather an example of a possible engagement
between a hostile force (the enemy attack aircraft) and
a Naval Weapons System (the ship). This scenario
illustrates the concept of the “detect-to-engage”
sequence, which is an integral part of the modern Fire
Control Problem. Although the scenario was one of a
surface ship against an air target, every weapon system
performs the same functions: target detection,
resolution or localization, classification, tracking,
weapon selection, and ultimately neutralization. In
warfare, these functions are performed by submarines,
aircraft, tanks, and even Marine infantrymen. The
target may be either stationary or mobile; it may travel
in space, through the air, on the ground or surface of the
COMPONENTS
All modern naval weapons systems, regardless of
the medium they operate in or the type of weapon they
use, consist of the basic components that allow the
system to detect, track and engage the target. Sensor
components must be designed for the environments in
which the weapon system and the target operate. These
components must also be capable of coping with
widely varying target characteristics, including target
range, bearing, speed, heading, size and aspect.
Detecting the Target
There are three phases involved in target detection
by a weapons system. The first phase is surveillance
and detection, the purpose of which is to search a
predetermined area for a target and detect its presence.
This may be accomplished actively, by sending energy
out into the medium and waiting for the reflected
energy to return, as in radar, or passively, by receiving
energy being emitted by the target, as by ESM in our
scenario. The second phase is to measure or localize
the target’s position more accurately and by a series of
such measurements estimate its behavior or motion
relative to ownship. This is done by repeatedly
determining the target’s range, bearing, and depth or
elevation. Finally, the target must be classified; that is,
its behavior must be interpreted to estimate its type,
number, size and most importantly identity. The
capabilities of weapon system sensors are measured by
Figure 2-24. —Successful engagement of a missile.
2-18
Figure 2-25. —Enemy submarine.
the maximum range at which they can reliably detect a
target and their ability to distinguish individual targets
in a multi-target group. In addition, sensor subsystems
must be able to detect targets in a medium cluttered
with noise, which is any energy sensed other than that
attributed to a target. Such noise or clutter is always
present in the environment due to reflections from rain
or the earth’s surface or because of deliberate radio
interference or jamming. It is also generated within the
electronic circuitry of the detecting device.
is to reduce this error to zero. Realistically this isn’t
possible, so when the error is minimal the sensor is said
to be “on target.” Sensor and launcher positions are
typically determined by devices that are used to
convert mechanical motion to electrical signals.
Synchro transformers and optical encoders are
commonly used in servo systems to detect the position
and to control the movement of power drives and
indicating devices. Power drives move the radar
antennas, directors, gun mounts, and missile
launchers.
Tracking the Target
The scenario presented in the beginning of this
section was in response to a single target. In reality, this
is rarely the case. The modern “battlefield” is one in
which sensors are detecting numerous contacts,
friendly and hostile, and information is continually
being gathered on all of them. The extremely high
speed, precision, and flexibility of modern computers
enable the weapons systems and their operators to
compile, coordinate, and evaluate the data, and then
initiate an appropriate response. Special-purpose and
general-purpose computers enable a weapons system
t o d e t e c t , t r a c k , a n d p r e d i c t t a rg e t m o t i o n
automatically. These establish the target’s presence
and define how, when, and with what weapon the target
will be engaged.
Sensing the presence of a target is an essential first
step to the solution of the fire control problem. To
successfully engage the target and solve the problem,
updates of the target’s position and velocity relative to
the weapon system must be continually estimated.
This information is used to both evaluate the threat
represented by the target and to predict the target’s
future position and a weapon intercept point so the
weapon can be accurately aimed and controlled. To
obtain target trajectory information, methods must be
devised to enable the sensor to follow or track the
target. This control or “aiming” may be done by a
collection of motors and position-sensing devices
called a servo system. Inherent in the servo process is a
concept called feedback. In general, feedback provides
the system with the difference between where the
sensor is pointing and where the target is actually
located. This difference is called system error. The
system takes the error and, through a series of
electro-mechanical devices, moves the sensor or
weapon launcher in the proper direction and at a rate
that reduces the error. The goal of any tracking system
Engaging the Target
Effective engagement and neutralization of the
target requires that a destructive mechanism, in this
case a warhead, be delivered to the vicinity of the target
(see figure 2-24). How close to the target a warhead
must be delivered depends on the type of warhead and
the type of target. In delivering the warhead, the
2-19
aiming, launch, type of weapon propulsion system,
and the forces to which the weapon is subjected
enroute to the target must be considered. The weapon’s
capability to be guided or controlled after launch
dramatically increases its accuracy and probability of
kill. The use of guidance systems also dramatically
complicates system designs. These factors as well as
the explosive to be used, the fuzing mechanism, and
warhead design are all factors in the design and
effectiveness of a modern weapon.
scenario is extremely important to every Fire
Controlman. Doing so will give you a clear, firm grasp
of what your ship does in a battle scenario and how you
fit in the big picture of naval warfare for your ship.
You should also understand the fire control problem in
relationship to this scenario. The detect-to-engage
process and fire control problem work together to
accomplish the goal of destroying an enemy target.
Each ship has its own, unique configuration of
weapons and radar systems; it is your responsibility as
a Fire Controlman to learn how these work together in
the detect-to-engage sequence and the fire control
problem.
Q9. What is the sequence of events in fire control that
begins with the initial detection of an enemy
target and ends with the destruction of that
target?
ANSWERS TO CHAPTER QUESTIONS
Q10. What phase of target detection estimates the
type, number, size, and identity of a target?
A1. Variation in frequency .
A2. TICONDEROGA class cruisers and ARLEIGH
BURKE class destroyers.
SUMMARY
A3. The AN/SPG-62 radar.
This chapter has given you an overview of many of
the radar systems used in today’s Navy. The goal of
this chapter was not to tell you about every radar
system or every detail of every radar system, but to
simply explain what radar systems are found on which
ships in the Navy and on what types of ships you will
find various radar systems.
A4. Air, surface, and beacon.
A5. The Mk 91 Guided Missile Fire Control System..
A6. The Perry class frigate.
A7. Non-AEGIS ships.
A8. A shipboard electro-optical system.
One of the key tools used for the “detectto-engage” scenario is radar systems. Understanding
how your ship accomplishes the detect-to-engage
A9. Detect-to-engage.
A10. The classification phase.
2-20
CHAPTER 3
RADAR SAFETY
LEARNING OBJECTIVES
Upon completing this section, you should be able to:
1. Identify and explain the radiation hazards associated with maintaining and
operating radar.
2. Identify the safety precautions associated with maintaining radar equipment.
3. Identify safety devices associated with maintaining radar equipment.
4. Identify other hazards associated with maintaining radar equipment.
with the actual radiation hazard zones of the radar on
your ship.
INTRODUCTION
Throughout your military career, you will be
“bombarded” with safety slogans, rules, and
procedures concerning almost every job that you do.
There is a reason for this. Your command is trying to
keep you alive and well. Your part in this process is to
become safety “conscious” to the point that you
approach every job from the safety point of view. In
this chapter, we will address the specific safety
measures and devices associated with operating and
maintaining radar equipment.
Whenever you work around radar equipment,
observe the following precautions to avoid being
exposed to harmful RFR:
• Do not inspect feedhorns, open ends of
waveguides or any opening emitting RFR energy
visually unless you are sure that the equipment is
definitely secured for that purpose.
• Observe all RFR hazard (RADHAZ) warning
signs (fig. 3-8). They point out the existence of
RFR hazards in a specific location or area.
RADIATION SAFETY
• Ensure that radiation hazard warning signs are
available and used.
One of the hazards associated with maintaining
radar equipment is exposure to RFR (Radio Frequency
Radiation). Radar peak power may reach a million
watts or more. Therefore, you must remain aware of
the RFR hazards that exist near radar transmitting
antennas. These hazards are present not only in front of
an antenna but also to its sides and sometimes even
behind it because of spillover and reflection. Exposure
to excessive amounts of radiation can produce bodily
injuries ranging from minor to major (Think of how
food is cooked in a microwave oven.). The extent of
injuries depends on the RFR frequency and the time of
exposure. At some frequencies, exposure to excessive
levels of radiation will produce a noticeable sensation
of pain or discomfort to let you know that you have
been injured. At other frequencies, you will have no
warning of injury. If you suspect any injury, see your
ship’s doctor or corpsman. Be sure to acquaint yourself
• Ensure that radar antennas that normally rotate
are rotated continuously or that they are trained
to a known safe bearing while they are radiating.
HAZARDS OF ELECTROMAGNETIC
RADIATION
Studies have shown that humans cannot easily
sense electromagnetic radiation (EMR), also referred
to as radio frequency radiation (RFR). Furthermore,
EMR at frequencies between 10 kilohertz (kHz) and
300 gigahertz (GHz) presents a hazard to humans and
to some materials. Since radiation at these frequencies
i s c o m m o n i n t h e N av y ’s e l e c t r o m a g n e t i c
environment, its presence must be detected and
announced to ensure the safety of personnel involved
3-1
affected by the RFR environment. Those
classifications are:
in various activities within the electromagnetic
environment. A discussion of the various methods
used to detect electromagnetic energy is beyond the
scope of this TRAMAN. However, we must emphasize
the importance of remaining alert to the danger of
overexposure to electromagnetic radiation.
1. HERO Safe. An ordnance item sufficiently
shielded or protected to make it immune to
adverse effects from RFR when used in its
expected shipboard RFR environments.
Radiation hazards can be broken down into three
categories:
2. HERO susceptible. Ordnance containing EEDs
proven by tests to be adversely affected by RFR
energy to the point that safety or reliability may
be in jeopardy when the ordnance is used in RFR
environments.
• Hazards of Electromagnetic Radiation to
Ordnance (HERO)
• Hazards of Electromagnetic Radiation to Fuel
(HERF)
3. HERO unsafe. Any electrically initiated
ordnance item that becomes unsafe when:
• Hazards of Electromagnetic Radiation to
Personnel (HERP)
a. Its internal wiring is physically exposed.
b. Tests being conducted on the item require
additional electrical connections to be made.
We will discuss each of these categories in more
detail in the following paragraphs.
c. Electroexplosive devices (EEDs) having
exposed wire leads are present, handled, or
loaded.
Hazards of Electromagnetic Radiation to
Ordnance (HERO)
d. T h e i t em i s b ei n g as s em b l e d o r
disassembled.
The high intensity radio frequency (RFR) fields
produced by modern radio and radar transmitting
equipment can cause sensitive electroexplosive
devices (EEDs) contained in ordnance systems to
actuate prematurely. The Hazards of Electromagnetic
Radiation to Ordnance (HERO) problem was first
recognized in 1958. The prime factors causing the
problem have been increasing ever since. The use of
EEDs in ordnance systems has become essential. At
the same time, the power output and frequency ranges
of radio and radar transmitting equipment have also
increased.
e. The item is in a disassembled condition.
f. The item contains one or more EEDs and has
not been classified as HERO safe or
susceptible by either a test or design
analysis.
To ensure the HERO safety and HERO reliability
of ordnance systems, the Naval Sea Systems
Command sponsors an extensive testing program to
determine their susceptibility to RFR energy. HERO
requirements and precautions are provided in
NAVSEA OP 3565/NAVAIR 16-1-529/NAVELEX
0967-LP-624-6010/Volume II, Electromagnetic
Radiation Hazards (U) (Hazards to Ordnance) (U).
You will find your ship’s specific requirements in its
HERO Emission Control (EMCON) bill.
RFR energy may enter an ordnance item through a
hole or crack in its skin or through firing leads, wires,
and so on. In general, ordnance systems that are
susceptible to RFR energy are most susceptible during
assembly, disassembly, loading, unloading, and
handling in RFR electromagnetic fields.
The commanding officer of each ship or shore
station is responsible for implementing HERO
requirements. He or she must also establish a
procedure to control radiation from radio and radar
antennas among personnel handling ordnance and
personnel controlling radio and radar transmitters. The
commanding officer does this through a command
instruction based on the ship’s mission and special
features. This instruction is usually part of the Ship’s
Organization Manual and is the basis for department
and division instructions.
The most likely results of premature actuation are
propellant ignition or reduction of reliability by
dudding. Where out-of-line Safety and Arming (S + A)
devices are used; the actuation of EEDs may be
undetectable unless the item is disassembled. If the
item does not contain an S + A device, or if RFR energy
bypasses the S + A device, the warhead may detonate.
Ordnance items susceptible to RFR can be
assigned one of three HERO classifications, based
upon the probability that they will be adversely
3-2
Hazards of Electromagnetic Radiation
to Fuels (HERF)
2. There must be enough energy in the arc or spark
to produce the appropriate temperature for
ignition.
Many studies have been done about fuel vapors
being accidentally ignited by electromagnetic
radiation. Tests aboard ships and in laboratories have
shown that the chances of this happening are low
because of other conditions that must exist at the same
time to support combustion of the fuel. Although
accidental ignition of fuel by RFR is unlikely, you still
need to be aware of the potential hazards. The most
likely time this might occur is during a ship’s refueling
evolutions, commonly called UNREPs (Underway
Replenishment). Many ships also carry at least one
helicopter or have the ability to refuel a helicopter and,
therefore, carry fuel to support helo operations. All of
these operations are inherently dangerous by
themselves and require the utmost attention and
alertness. As a junior Fire Controlman you most likely
will be personally involved in these refueling
operations. You need to be aware of the potential
hazards associated with Fire-Control radar and fuel.
As a senior Fire Controlman, you need to know the
hazards of electromagnetic radiation to fuel, so you
can ensure that your division personnel are working in
a safe environment.
3. The length of the arc must be sufficient to
sustain the heat in the arc for the time required to
initiate a flame.
Each of these conditions is likely to vary for every
situation, and two of the conditions may exist at any
given time. Although all three conditions will probably
not occur simultaneously, the consequences of an
accidental explosion make it very important to be
careful.
Hazards of Electromagnetic Radiation to
Personnel (HERP)
The RFR hazard category of most immediate
concern to you is HERP. The heat produced by RFR
may adversely affect live tissue. If the affected tissue
cannot dissipate this heat energy as fast as it is
produced, the internal temperature of the body will
rise. This may result in damage to the tissue and, if the
temperature rise is sufficiently high, in death.
The Bureau of Medicine and Surgery has
established safe exposure limits for personnel who
must work in an electromagnetic field based on the
power density of the radiation beam and the time of
exposure in the radiation field. Before we discuss these
further, we must discuss some additional terms.
RADAR RESTRICTIONS.—Electromagnetic
Radiation Hazards (U) (Hazards to Personnel, Fuel
and Other Flammable Material) (U), NAVSEA OP
3565/NAVAIR16-1-529/NAVELEX 0967-LP-6246010/Volume I specifies the safe distances from
radiating sources at which fueling operations may be
conducted. Figure 3-1 indicates safe distances between
fueling operations and a conical monopole antenna,
based on transmitter power. Each type of antenna has
its own chart. Refer to your ship’s Emissions Control
(EMCON) bill for specific guidance concerning
fueling operations.
Specific Absorption Rate (SAR)—This is the rate
at which the body absorbs non-ionizing RFR. The
threshold at which adverse biological effects begin is 4
watts per kilogram of body mass (W/kg). With a safety
factor of 10 added, the accepted threshold is 0.4 W/kg
for the whole body, averaged over any 6-minute (0.1
hour) period. A special limit for “hot spot” or limited
body exposure has been set at 8.0 W/kg, averaged over
any 1 gram of body tissue for any 6-minute period.
Although this rate of absorption is very important in
determining whether or not a safety hazard exists, it is
very difficult to measure. Measuring this rate of
absorption can also be dangerous since it requires
actual exposure of body tissue. A related measure that
gives an acceptable indication of SAR is “Permissible
Exposure Limit”.
FUEL RESTRICTIONS.—As the RFR energy
radiated from high-powered communications and
radar equipment installed on ships increased in recent
years, the Navy shifted to less volatile fuels. Under
normal operating conditions, volatile mixtures are
present only near aircraft fuel vents, open fuel inlets
during over-the-wing fueling, and near fuel spills.
Permissible Exposure Limit (PEL)—This is a
limit to RFR exposure based on measurements of
radiation’s electric field strength (E) or magnetic
field strength (H) taken with instruments. You can
use available charts to determine whether the
Before fuel vapors can ignite, three conditions
must exist simultaneously:
1. For a given ambient temperature, the mixture
must contain a specific ratio of fuel vapor to air.
3-3
Figure 3-1.—Guidance Curve for Potential Fueling Hazards.
3-4
strength of the field presents a biological hazard to
personnel located at the point where the measurements
were taken. PEL readings are the basis for determining
RADHAZ safety boundaries.
the wavelength of the RFR. Thus, the wavelength of
the energy and its relationship to a person’s
dimensions are important factors bearing on the
biological effects produced by RFR.
Permissible Exposure Time (PET)—This is the
maximum time of exposure to a specific power density
for which the PEL will not be exceeded when the
exposure is averaged over any 6-minute period. Table
3-1 shows the PET for a variety of radars operated at
their normal power levels.
Significant energy absorption will occur only
when a personal dimension is equivalent to at least
one-tenth of a wavelength. As the frequency of
radiation increases, the wavelength decreases and the
person’s height represents an increasingly greater
number of electrical wavelengths, increasing the
danger from RFR exposure. As the frequency is
decreased, the wavelength increases and the person
becomes a less significant object in the radiation field.
Thus, the likelihood of biological damage increases
with an increase in radiation frequency. Also, as the
radiation frequency increases and the wavelength
becomes progressively shorter, the dimensions of parts
and appendages of the body become increasingly
significant in terms of the number of equivalent
electrical wavelengths.
If you suspect that you or someone else has been
overexposed to EMR, follow the flow chart in figure
3-2. If you confirm your suspicions, the exposure is
considered an incident and must be reported as
required by Protection of DOD Personnel from
Exposure to Radio Frequency Radiation, DOD
Instruction 6055.11.
RFR HAZARDS TO THE SKIN.—The energy
impinging on a person in an electromagnetic field may
be scattered, transmitted, or absorbed. The energy
absorbed into the body depends upon the dimensions
of the body, the electrical properties of the tissues, and
When a person stands erect in a RFR field, the
body is comparable to a broadband receiving antenna.
Figure 3-2.—Personnel RFR exposure decision chart.
3-5
Table 3-1.—Permissible Exposure Time Limits—Partial List
3-6
cutout switches that turn off the transmitter for certain
director bearings and elevations. The information
concerning cutout zones for your particular
installation is located in the radar OPs(Operational
Publications). You should know the cutout zones for
your particular radar. The equipment OPs also give the
radiation pattern and the minimum safe distance for
personnel exposed to the mainbeam of the radar. The
safe limit of radiation exposure to personnel,
established by the Naval Medical Command, is 10
mW/cm averaged over any one-tenth hour period (six
minutes). No exposure in a field with a power density
in excess of 100 mW/cm is permitted.
When any of the major body dimensions are parallel to
the RFR energy’s plane of polarization, the produced
effects are likely to be more pronounced than when
they are oriented in other positions.
The depth of penetration and coincident heating
effects of energy on the human body depend on the
energy’s frequency. The region of transition between
major damage and minor or no damage is between 1
and 3 GHz. Below 1 GHz, the RFR energy penetrates
to the deep body tissues. Above 3 GHz, the heating
effect occurs closer to the surface. At the higher
frequencies, the body has an inherent warning system
in the sensory elements located in the skin. At
frequencies between 1 and 3 GHz, the thermal effects
are subject to varying degrees of penetration, with the
percentage of absorbed energy ranging from 20 to 100
percent. The two microwave cooking oven frequencies
fall close to this range. The lower frequency, 915 MHz,
produces a deeper heating effect on tissue (i.e., roasts)
and is not as effective for surface cooking (browning)
as the higher frequency, 2,450 MHz.
2
2
RFR Burns
You can receive an RFR burn if your skin contacts
a source of RFR voltage. This is because your skin’s
resistance to the current flow in the area of contact
produces heat. The effect of this heat on your skin can
range from noticeable warmth to a painful burn.
Mild RFR burns are usually indicated by small
white spots on the skin and possibly the odor of
scorched skin. More severe burns may penetrate
deeper into the flesh and produce painful and slower
healing injuries. For our purposes, “hazardous” will be
associated with the RFR voltage level sufficient to
cause pain, visible skin damage, or an involuntary
reaction. The term hazard does not include the lower
voltage that causes annoyance, a stinging sensation, or
mild heating of the skin. The Naval Ships
Engineering Center has prescribed that an open
circuit RFR voltage exceeding 140 volts on an
object in an RFR radiation field be considered
hazardous.
R F R H A Z A R D TO T H E E Y E S . — T h e
transparent lens of the eye may be damaged by radiated
energy (ultraviolet, infrared, or radio frequency),
causing the development of cataracts or opacities. The
lens is very susceptible to thermal damage, since it has
an inefficient vascular system to circulate blood and
exchange heat to the surrounding tissues. Unlike other
cells of the body, the cells of the lens cannot be
replaced by regrowth. When cells in the lens die or
become damaged, a cataract may form. The damaged
cells may lose their transparency slowly and,
depending upon the extent of damage, cause the
individual to suffer impaired vision. Apparently, the
presence of even a relatively few damaged cells may
act upon other lens cells, either by releasing toxic
substances or by preventing normal chemical
transformation to take place within other cells.
A common source of potential RFR burns is crane
hooks. Transmitting antennas can induce RFR
voltages in nearby crane structures and wire ropes.
Figure 3-3 shows areas on a crane in which inductive
and capacitive charges may be induced by RFR. Some
crane/antenna problems can be eliminated by
relocating the associated antennas, but each
installation requires special considerations. The
locations of ship’s antennas are based on the desired
radiation patterns, taking into account the physical
limitations imposed by the ship’s structure. Often, the
relocation of antennas, although physically
permissible, is not feasible because of the location of
the associated transmitters.
RFR HAZARD TO THE TESTICLES.—
Testicular reaction to heat injury from excessive
exposure to RFR radiation can be the same as the
reaction to a high fever associated with many illnesses.
Although a condition of temporary sterility may occur,
the condition does not appear to be permanent and will
ultimately correct itself. However, injury to the
testicles may be permanent because of an extremely
high dosage or because of high exposures for extended
periods of time (i.e., months to years).
S H I P B OA R D R A D I AT I O N H A Z A R D
ZONES.—Because of the danger of radiation hazards
to personnel, the fire control radar is equipped with
RFR voltages measured aboard ships show that
resonance effects may occur at frequencies between 2
3-7
Figure 3-3.—Electrical equivalent of cargo handling equipment.
and 30 Mhz. The careful use of frequency can reduce
the coupling of RFR voltages induced in crane
structures and rigging. A better approach, however, is
the use of RFR high voltage insulator links, which
provide protection for personnel against RFR burns.
(Refer to Link RFR High Voltage Insulator for Ship
Cranes, MIL-L-24410 (SHIPS)). Two separate bands
of fiberglass filament wound on two zinc-coated steel
saddles provide the required high electrical resistance,
low capacitance, high tensile strength, ruggedness and
fail-safe features of the insulator links. While the inner
band normally carries the full working load, the outer
band can carry the full working load if the inner band
breaks.
AND HELICOPTERS) THAT PROTRUDE FROM
THE SHIP IN THE SAME PLANE AS THE
RADIATING SOURCE. The RFR voltage induced in
a ship’s structures, rigging, or other objects will cause
burns to personnel when they contact conductive
objects. The burn hazard problem, its causes, and
remedial techniques are discussed in chapter 3 (“RFR
Burns”) of Electromagnetic Radiation Hazards (U)
(Hazards to Personnel, Fuel and Other Flammable
Material) (U), NAVSEA OP 3565/NAVAIR
16-1-529/ NAVELEX 0967-LP-624- 6010/Volume I.
Q1. What do the letters RFR stand for when
associated with radiation safety?
Q2. What are the three categories of electromagnetic
radiation hazards?
When proper precautions are taken, personnel
handling rigging will not be harmed as long as nearby
electronic transmitting equipment is operated at an
output of 250 watts or less, average (at any frequency).
H OW E V E R , P E R S O N N E L S H O U L D B E
CONSTANTLY ALERT TO THE FACT THAT
EVEN UNDER THE ABOVE OPERATIONAL
L I M I T S , E L E C T RO N I C T R A N S M I T T I N G
E Q U I P M E N T C A N C AU S E H A Z A R D O U S
VOLTAGES TO BE INDUCED IN THE STANDING RIGGING AND OTHER PORTIONS OF A
S H I P ’ S S T RU C T U R E , PA RT I C U L A R LY
STRUCTURES AND OBJECTS (i.e., AIRPLANES
Q3. What are the three classifications of ordnance
susceptible to RFR?
Q4. What NAVSEA publication specifies safe
distances from radiation sources for fueling?
Q5. If you confirm that someone has been
overexposed to RFR, what instruction must you
use to properly report the incident?
Q6. According to the Naval Ships Engineering
Center, what is the minimum RFR voltage in an
open circuit that qualifies as hazardous?
3-8
MAN ALOFT SAFETY
TIME _______ INITIALS ________ ” is placed on
the equipment.
Since many areas on the exterior of a ship that
contain radar equipment are inaccessible from decks or
built-in work platforms, someone must go aloft to
work in these areas. We define “aloft” as any mast,
kingpost, or other structure where the potential for a
fall exists. Probably the greatest hazard associated
with working aloft is the danger of a fall. Other hazards
include electrical shock, radiation burns, asphyxiation
from stack gasses, and the dropping of objects.
You should always check your ship’s instruction
(Man Aloft Bill) for specific guidance before you go
aloft. Here are some general guidelines to follow when
you go aloft:
1. Use a climber sleeve assembly in conjunction
with the safety harness where a climber safety
rail is installed.
2. Attach safety lanyards to all tools, if practical.
Never carry tools up and down ladders. Rig a
line and raise or lower your tools in a safe
container.
As long as nearby equipment is turned off, you
should not have to worry about receiving a shock from
current generated by the equipment. However, you
must be aware of the possibility of shock due to static
charges. Static charges are caused by electrically
charged particles that exist naturally in the water.
Under certain conditions these charged particles
collect on metallic objects such as wire antennas and
produce a shock hazard. You can eliminate this hazard
by grounding these objects. Shocks from static charges
will not harm you directly, but the surprise of such a
shock may cause you to fall.
3. Stop work when the ship begins to roll in excess
of 10 degrees, or to pitch in excess of 6 degrees,
when wind speed is greater than 30 knots, and
when an ice storm or lightning threatens.
4. Be sure the petty officer-in-charge has marked
off an area below the zone of work and keeps all
unnecessary personnel clear. If the slightest
chance of danger exists, have personnel in the
area moved to safety.
WORKING ALOFT CHECK SHEET
5. Read all safety placards posted in the area before
you begin the work.
Because of the associated dangers, no one may go
aloft on masts, stacks, or kingposts without first
obtaining permission from the Officer of the Deck
(OOD), as prescribed by the Navy Occupational Safety
and Health (NAVOSH) Program Manual for Forces
Afloat, OPNAVINST 5100.19 series. Before granting
permission, the OOD must ensure that the Working
Aloft Check Sheet (fig. 3-4) has been properly
completed and routed. When the ship is underway, the
commanding officer’s permission is required to work
aloft. The OOD will ensure that appropriate signal
flags are hoisted. (KILO for personnel working aloft;
KILO THREE for personnel working aloft and over the
side.) Before the work begins and every 15 minutes
thereafter, he will have the word passed over the 1 MC,
“ D O N OT ROTAT E O R R A D I AT E A N Y
ELECTRICAL OR ELECTRONIC EQUIPMENT
WHILE PERSONNEL ARE WORKING ALOFT.”
Additionally the OOD will inform the ships in the
vicinity that personnel will be working aloft to ensure
that they take appropriate action on the operation of
their electrical and electronic equipment. Departments
concerned must ensure that all radio transmitters and
radars that pose radiation hazards are placed in the
STANDBY condition and that a sign reading
“SECURED. PERSONNEL ALOFT. DATE _______
6. Wear personal protective equipment, such as
hearing protection, goggles, gloves, or a
respirator for hazards other than RFR.
7. When you perform hot work, replace the
personal safety and staging or boatswain chair
fiber lines with wire rope. Personal safety lines
must consist of CRESS wire rope.
Most ships in today’s Navy are aviation capable.
Any loose materials or tools that you leave in an
outside work area may become foreign object damage
(FOD) material. FOD material can be sucked into
aircraft engines (causing extensive damage) or blown
around by engine exhaust or rotor wash (possibly
injuring someone). You must learn the importance of
foreign object damage (FOD) control. Supervisory
personnel are responsible for ensuring that assigned
personnel who work on the mast and other topside
areas receive training on the importance of FOD
control. After completing any work topside, you must
ensure that all tools and materials are removed from the
work area. Metallic items left in these areas may also
create electromagnetic interference problems.
3-9
Figure 3-4.—Sample Working Aloft Check Sheet.
SAFETY HARNESS
use.) Safety harnesses should be checked periodically
as prescribed by the Planned Maintenance System.
Place the tools that you will use on the job in a canvas
bag and haul the bag up with a line to the job location.
To guard against dropping tools and seriously injuring
someone, tie the tool you are using to your safety
harness with a piece of line.
For your own safety, you should wear an approved
parachute-type safety harness (fig. 3-5) with a safety
lanyard and a tending line (as required) with double
locking snap hooks whenever you work aloft. (The
lineman-type safety belt is no longer authorized for
3-10
3. Safety lanyard with dynabrake
(NSN-9G-4240-00-022-2521)
4. Safety harness
(NSN-9G-4240-00-022-2522)
5. Safety climbing sleeve
(NSN-9G-4240-01-042-9688)
WARNING SIGNS
Warning signs and suitable guards should be
posted conspicuously in the appropriate places for the
following purposes:
• To keep personnel from accidentally coming
into contact with dangerous voltages;
• To warn personnel about possible explosive
vapors and RFR radiation;
• To warning personnel working aloft about the
poisonous effects of stack gases;
• To warn of other dangers that may cause injuries
to personnel.
Installation of equipment is not considered
complete unless appropriate warning signs are posted
conspicuously.
HIGH VOLTAGE WARNING SIGN
High voltage and shock hazard warning signs
should be installed on or in the vicinity of equipment or
accessories having exposed conductors at potentials of
30 volts (root mean square or dc) or above. Exposed
conductors include those from which personnel may
receive a shock by physical contact or by voltage arc
over. The signs should be posted so that they are
obvious and can be clearly read by personnel entering
the area.
Compartments or walk-in enclosures containing
equipment with exposed conductors presenting shock
hazards in excess of 500 volts (root mean square or dc)
should have a “Danger High Voltage” sign (fig. 3-6)
posted conspicuously within each entrance.
Figure 3-5.—Parachute-type safety harness.
The safety harness assembly consists of the
following components:
Compartments or walk-in enclosures containing
equipment with exposed conductors presenting shock
hazards between 30 volts (RMS or dc) and 500 volts
(RMS or dc) should have either a “Danger High
Voltage” sign or a “Danger Shock Hazard” sign posted
conspicuously within each entrance.
1. Safety harness with lanyards
(NSN-9G-4240-00-402-4514)
2. Working lanyard nylon
(NSN-9G-4240-00-022-2518)
3-11
The signs shown in figure 3-8 were approved for
use in 1990. Some old style signs may still be posted in
various work areas. If you find older style RADHAZ
signs posted in an area, you do not have to replace them
with the new style signs unless they are damaged or
illegible.
The purpose of each type of RADHAZ sign is
explained below.
Type 1—“WARNING RADIO FREQUENCY
HAZARD . . . KEEP MOVING”
The type 1 sign advises personnel not to linger in
an area surrounding HF antennas where RFR
permissible exposure limit (PEL) can be exceeded.
There is no danger from exposure to HF radiation in
these areas for short periods. However, no one should
remain within the area (defined by a 4-inch red
line/circle on the deck) longer than 3 minutes within a 6
minute period.
Figure 3-6.—High voltage warning sign.
STACK GAS WARNING SIGN
A warning sign to alert personnel working aloft
near smoke pipe (stack) gases is shown in figure 3-7.
One sign should be mounted near the bottom of each
access ladder leading aloft. Another sign should be
located at the top of each ladder but mounted on the
base of the antenna pedestal.
When type 1 signs are required, install them at eye
level, or where they can be seen easily, outside the PEL
boundary.
RFR HAZARD WARNING SIGNS
Type 2—“WARNING RADIO FREQUENCY
HAZARD . . . BEYOND THIS POINT”
There are six RFR radiation hazard (RADHAZ)
warning signs (fig.3-8). Requisitioning information is
provided on the signs themselves. Consult with your
leading petty officer (LPO) to obtain the appropriate
signs if they are not posted in your workspace.
The type 2 sign is used to keep personnel from
proceeding past a designated point unless they comply
with established RADHAZ avoidance procedures.
These procedures are discussed in ship’s doctrine, such
as the “MAN ALOFT BILL.” You will probably not
find deck markings in these areas.
RADHAZ signs are made of anodized aluminum
and come in two authorized sizes: large (14-inches by
14-inches) and small (5-inches by 5-inches). The large
signs are reserved for shore use. The small signs may
be used either aboard ship or ashore.
Type 2 signs are installed at eye level at the bottom
of vertical ladders or suspended at waist level between
the handrails of inclined ladders. When type 2 signs are
used as temporary barriers, such as when weapons
direction radars are radiating, they are installed at
waist level on a nonmetallic line.
Type 3—“WARNING RADIO FREQUENCY
HAZARD . . . BURN HAZARD”
PERSONNEL ARE CAUTIONED TO GUARD
AGAINST POISONOUS EFFECTS OF SMOKE PIPE
GASES WHILE SERVICING EQUIPMENT ALOFT.
WHEN SERVICING EQUIPMENT IN THE WAY
OF SMOKE PIPE GASES USE OXYGEN BREATHING
APPARATUS AND A TELEPHONE CHEST OR
THROAT MICROPHONE SET FOR COMMUNICATION
WITH OTHERS IN WORKING PARTY.
OBTAIN NECESSARY EQUIPMENT BEFORE
GOING ALOFT.
The type 3 sign advises personnel to use special
handling procedures when they touch a designated
metallic object, or simply to not touch it. This object is
an RFR burn source when it is illuminated by energy
from a nearby transmitting antenna. Although the
hazard may exist only at certain frequencies or power
levels, personnel should regard the object as a hazard
unless the transmitter is secured.
Figure 3-7.—Stack gas warning sign.
3-12
G
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3-13
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Figure 3-8.—Sample RADHAZ signs.
RADHAZ warning signs are not appropriate.
Examples of directions that can be filled in on a type 5
sign include:
NOTE: Whenever possible, the RFR burn source
should be replaced with a nonmetallic substitute or
relocated or reoriented to eliminate the hazard before
resorting to a type 3 sign for personnel protection.
• “Inform OOD before placing system in radiate.”
A type 3 sign should be installed on the RFR burn
source or in the immediate vicinity where it can be seen
easily. When used on cargo handling running rigging,
type 3 signs should be mounted on the hook insulator.
Personnel should be warned to not touch the
wire/rigging above the insulator. More than one type 3
sign should be installed on larger burn sources that can
be approached from multiple directions.
• “In manual mode, do not depress below horizon
between ______ and _______ degrees relative.”
• “Ensure temporary exclusion barriers are in
place before radiating.”
• “Do not stop antenna between _______ and
_______ degrees while radiating.”
Type 4—“WARNING RADIO FREQUENCY
HAZARD . . . FUELING OPERATIONS”
A type 5 sign is normally installed below decks in a
system operating room. It should be installed in the
vicinity of controls such as a radiate switch or antenna
control switch, where the person operating the gear in
normal operation can see it. When mounted on system
cabinets or control panels, RADHAZ signs should not
obscure switch labels, meters, indicators or nameplate
data.
The type 4 sign advises of the hazards of
electromagnetic radiation to fuels (HERF). These
signs are normally used only on ships that carry
aviation gasoline (AVGAS) or automotive gasoline
(MOGAS). Marine diesel fuel and JP-5 jet fuel are not
considered to have a HERF problem and require no
special electromagnetic safety precautions during
fueling. Most naval ships do not carry gasoline. An
exception to this is amphibious ships carrying
gasoline-powered landing vehicles. Aboard ships that
carry AVGAS or MOGAS, personnel should observe
the following precautions during fueling or fuel
transfer operations:
Type 6—“WARNING RADIO FREQUENCY
HAZARD . . . HAZARD TO ORDNANCE”
The type 6 sign advises of hazards of
electromagnetic radiation to ordnance (HERO).
NAVSEA OP 3565 explains the purpose of HERO
signs and where to place them.
1. Secure all transmitting antennas located within
the quadrant of the ship in which fueling is being
conducted.
ROTATION HAZARD WARNING
Rotating directors present a serious danger to
personnel near them. To guard against this hazard, be
sure the topside area near the directors is cleared of all
personnel before you energize a director. “DANGER
ROTATION HAZARD” warnings should also be
posted or painted in conspicuous places to alert unwary
personnel.
2. Ensure that RADHAZ cutouts for microwave
radiators are not overridden during fueling,
which could result in the illumination of the
fueling areas.
3. Do not energize any radar or communications
transmitter on any aircraft or vehicle.
4. Do not make or break any electrical, static
ground wire, or tie down connection, or any
metallic connection to the aircraft or motor
vehicle while it is being fueled. Make the
connections before the fueling commences.
Break them afterward.
Q7. What OPNAV instruction gives the OOD
guidance for the Working Aloft Check Sheet?
Q8. What size RADHAZ signs should be used on
ships?
Q9. What type of RADHAZ warning signs should be
used when other RADHAZ signs are NOT
appropriate?
Type 5—“WARNING RADIO FREQUENCY
HAZARD (SPECIAL CONDITION)”
OTHER RADAR HAZARDS
The type 5 sign has a blank area for filling in
special safety precautions. Its purpose is to advise
personnel of procedures to follow when other
The hazards we discussed above occur primarily
on the exterior of the ship. We now need to discuss
3-14
some of the radar hazards you may encounter inside the
ship.
are broken, the radioactive material may become a
potential hazard.
The radioactivity in a normal collection of electron
tubes in a maintenance shop does not approach a
dangerous level, and the hazards of injury from
exposure are slight. However, at major supply points,
the storage of large quantities of radioactive electron
tubes in a relatively small area may create a hazard. If
you work in an area where a large quantity of
radioactive tubes is stored, you should become
thoroughly familiar with the safety practices contained
in Radiation Health Protection Manual, NAVMED
P-5055. By complying strictly with the prescribed
safety precautions and procedures of this manual, you
should be able to avoid accidents and maintain a work
environment that is conducive to good health.
CATHODE-RAY TUBES (CRTs)
Cathode-ray tubes can be very dangerous and
should always be handled with extreme caution. The
glass envelope encloses a high vacuum, and because of
its large surface area, is subject to considerable force
by atmospheric pressure. (The total force on the
surface of a 10-inch CRT is 3,750 pounds or nearly 2
tons; over 1,000 pounds is exerted on its face alone.)
Proper handling and disposal instructions for a CRT
are as follows:
• Avoid scratching or striking the surface.
• Do not use excessive force when you remove or
replace the CRT in its deflection yoke or its
socket.
The hazardous materials information system
(HMIS) contains a listing of radioactive tubes, along
with proper stowage techniques and disposal
procedures. Afloat Supply Procedures, NAVSUP
P-485 contains detailed custody procedures. Be sure
you use proper procedures whenever you dispose of a
radioactive tube. Also, be aware that federal and state
disposal regulations may vary.
• Do not try to remove an electromagnetic CRT
from its yoke until you have discharged the high
voltage from the anode connector (hole).
• Never hold a CRT by its neck.
Any time you handle radioactive electron tubes,
take the following precautions:
• When you set a CRT down, always place its face
down on a thick piece of felt, rubber, or smooth
cloth.
1. Do not remove a radioactive tube from its carton
until just before you actually install it.
• Always handle the CRT gently. Rough handling
or a sharp blow on the service bench can displace
the electrodes within the tube, causing faulty
operation.
2. When you remove a tube containing a
radioactive material from equipment, place it in
an appropriate carton to keep it from breaking.
3. Never carry a radioactive tube in your pocket, or
elsewhere on your person, in such a way that
could cause the tube to break.
• Wear safety glasses and gloves whenever you
handle a CRT.
4. If you do break a radioactive tube, notify the
appropriate authority and obtain the services of
qualified radiological personnel immediately.
The basic procedures for cleaning the area are
covered in the EIMB, General, Section 3. If you
are authorized to clean the area, get a radioactive
spill kit with all the materials to clean the area
quickly and properly. The ship must have at least
one radioactive spill disposal kit for its
electronic spaces. It may have more, depending
on the number and location of spaces in which
radioactive tubes are used or stored. Each kit
should contain the following items:
RADIOACTIVE ELECTRON TUBES
Electron tubes containing radioactive material are
common to radar equipment. These tubes are known as
Transmit-Receive (TR), antitransmit-receive (ATR),
spark-gap, voltage-regulator, gas-switching, and
cold-cathode gas-rectifier tubes. Some of these tubes
contain radioactive material that has a dangerous
intensity level. Such tubes are so marked according to
military specifications. In addition, all equipment
containing radioactive tubes must have a standard
warning label attached where maintenance personnel
can see it as they enter the equipment.
• Container—Must be large enough to hold all
As long as these electron tubes remain intact and
are not broken, no great hazard exists. However, if they
cleanup materials and pieces of broken
3-15
9. Wear rubber or plastic gloves at all times during
cleanup and decontamination procedures.
radioactive tubes and must be airtight. A
three-pound coffee can with a plastic lid or
30/50 caliber ammo box is an acceptable
container. The container must be clearly
m ar ke d
“R ADIOAC TIVE
S P IL L
DISPOSAL KIT.”
10. Use a HEPA filtered vacuum cleaner (with an
approved disposal collection bag) to remove the
pieces of the tube. The vacuum cleaner should
be designated for “Spill Response” or “For
Cleanup of Radioactive Materials ONLY” and
use the standard magenta/yellow markings for
labeling. If a vacuum cleaner is not available,
use forceps and/or a wet cloth to wipe the
affected area. In this case, be sure to make one
stroke at a time. DO NOT use a back-and-forth
motion. After each stroke, fold the cloth in half,
always holding one clean side and using the
other for the new stroke. (Dispose of the cloth in
the manner stated in item 14.)
• Rubber gloves—Two pairs of surgical latex
gloves to prevent contact with contaminated
material.
• Forceps or hemostats—Used for picking up
large pieces.
• Masking tape—One roll of 2-inch-wide tape
for picking up small pieces.
• Gauze pads or rags—One stack of 4-inch
gauze pads (50 pads or more) for wiping down
the area. Do NOT use sponges.
11. Do not allow any food or drink to be brought into
the contaminated area or near any radioactive
material.
• Container of water—A small container of
water (approximately 2 ounces) in an
unbreakable container, for wetting the gauze
pads or rags.
12. Immediately after leaving a contaminated area,
if you handled radioactive material in any way,
remove any contaminated clothing. Also wash
your hands and arms thoroughly with soap and
water and rinse them with clean water.
• Boundary rope and appropriate signs—Used
for marking the contaminated area.
• Respirator—With filters that are specific for
13. Immediately notify a medical officer if you
sustain a wound from a sharp radioactive object.
If a medical officer can not reach the scene
immediately, stimulate mild bleeding by
applying pressure about the wound and using
suction bulbs. DO NOT USE YOUR MOUTH.
If the wound is a puncture type, or the opening is
small, make an incision to promote free
bleeding, and to enable cleaning and flushing of
the wound.
radionuclides.
• Radioactive material stickers—For labeling
the material to be disposed of. (These can be
made locally).
• Two 12-inch plastic bags—For containing the
used material.
• Pr oced ures—Step-by-step
cl ean u p
procedures.
14. When you clean a contaminated area, seal all
debris, cleaning cloths, and collection bags in a
container such as a plastic bag, heavy wax paper,
or glass jar. Place the container in a steel can
u n t i l i t can b e d i s p o s ed o f p r o p e r l y.
Decontaminate, using soap and water, all tools
and implements you used to remove a
radioactive substance. Monitor the tools and
implements for radiation with an authorized
radiac set. They should emit less than 0.1
MR/HR at the surface. (MR/HR is the
abbreviation for milliroentgen/hour,which is
defined as a unit of radioactive dose of
exposure.)
• Other items recommended by the type
commander and the fleet training group.
5. Isolate the immediate area of exposure to protect
other personnel from possible contamination
and exposure.
6. Follow the established procedures set forth in
NAVMED P-5055.
7. Do not permit contaminated material to contact
any part of your body.
8. Avoid breathing any vapor or dust that may be
released by tube breakage.
3-16
References to Consult Concerning Radioactive
Tubes
• Observe all warning signs (fig. 3-9) on the
equipment and all written precautions in the
equipment technical manual.
The following is a basic list of publications
conerning the handling and use of radioactive tubes.
• Do NOT bypass interlocks that prevent the
servicing of operating equipment with the x-ray
shield removed, unless the technical manual
requires you to do so.
– Department of Defense Hazardous Materials
Information System (HMIS), DOD 6050.1-L
• Be sure to replace all protective x-ray shielding
when you finish the servicing.
– Radiatio n He alth Prote ction Ma n u a l,
NAVMED P-5055
Q10. What publication gives basic cleanup
procedures for a broken, radioactive tube?
– Afloat Supply Procedures, NAVSUP P-485
– EIMB, General
SUMMARY
– EIMB, Radiac
This chapter has presented radar safety measures
you are expected to practice in your daily work. As
with electrical and electronic safety, the greatest
danger you will face as a Fire Controlman is becoming
too familiar with the safety hazards you will face.
COMPLACENCY KILLS! Radio frequency energy is
not the only hazard associated with working around
radar. Working aloft has its own set of hazards. Be
– Safety Precautions for Forces Afloat
– Naval Ships’ Technical Manual, Chapter 400
Technical Assistance
For technical assistance and advice regarding
identification, stowage, or disposal of radioactive
tubes, contact:
Officer In Charge
Naval Sea Systems Command Detachment
Radiological Affairs Support Officer
(NAVSEADET, RASO)
Naval Weapons Station
Yorktown, VA 23691-5098
CAUTION
X-RAY EMISSIONS
X-RAY
X-rays may be produced by high-voltage
electronic equipment. X-rays can penetrate human
tissue and cause both temporary and permanent
damage. Unless the dosage is extremely high, there
will be no noticeable effects for days, weeks, or even
years after the exposure.
The sources of these x-rays are usually confined to
magnetrons, klystrons, and CRTs. Where these types
of components are used, you should not linger near any
equipment on which the equipment covers have been
removed. Klystrons, magnetrons, rectifiers, or other
tubes that use an excitation of 15,000 volts or more
may emit x-rays out to a few feet, thus endangering you
or other unshielded personnel standing or working
close to the tubes.
If you must perform maintenance on x-ray
emitting devices, take the following precautions:
Figure 3-9.—X-ray caution label.
3-17
aware of your environment and other evolutions that
are happening around you. It is your responsibility to
know what warning signs mean and where they should
be posted. Remember, as a Fire Controlman, you have
a responsibility to yourself and to your shipmates to
always be alert to detect and report hazardous work
practices and conditions.
A4. NAVSEA OP 3565, Volume 1.
A5. DOD Instruction 6055.11. Protection of DOD
Personnel from Exposure to Radio Frequency
Radiation.
A6. 140 volts.
A7. OPNAVINST 5100.19 series, Navy Occupational
Safety and Health (NAVOSH) Program Manual
for Forces Afloat.
ANSWERS TO CHAPTER QUESTIONS
A1. Radio Frequency Radiation.
A8. Small (5 inch by 5 inch).
A2. Hazards of Electromagnetic Radiation to
Ordnance (HERO), Hazards of Electromagnetic
Radiation to Fuel (HERF), and Hazards of
Electromagnetic Radiation to Personnel
(HERP).
A9. Type 5, Warning Radio Frequency Hazard
(Special Condition).
A10. EIMB, General, Section 3.
A3. HERO safe, HERO susceptible, and HERO
unsafe.
3-18
APPENDIX I
REFERENCES
NOTE: Although the following references were current when this NRTC
was published, their continued currency cannot be assured. Therefore, you
need to be sure that you are using the latest version.
Chapter 1
Combat Systems Technical Operations Manual (CSTOM)
Electronics Installation and Maintenance Book-General, NAVSEA
SE000-00-EIM-100, Electronics Installation and Maintenance Book (EIMB),
Naval Sea Systems Command, Washington, DC, 1983.
Navy Electricity and Electronics Training Series (NEETS), Module 9,
Introduction to Wave-Generation and Wave-Shaping Circuits, NAVEDTRA
172-09-00-83, Naval Education and Training Professional Development and
Technology Center, Pensacola, FL, 1983.
Navy Electricity and Electronics Training Series (NEETS), Module 10,
Introduction to Wave Propagation, Transmission Lines, and Antennas,
NAVEDTRA B72-10-00-93, Naval Education and Training Program
Management Support Activity, Pensacola, FL, 1993.
Navy Electricity and Electronics Training Series (NEETS), Module 11,
Microwave Principles, NAVEDTRA 172-11-00-87, Navy Education and
Training Program Management Support Activity, Pensacola, FL, 1987.
Navy Electricity and Electronics Training Series (NEETS), Module 15, Principles
of Synchros, Servos, and Gyros, NAVEDTRA B72-15-00-93, Naval
Education and Training Program Management Support Activity, Pensacola,
FL, 1993.
Navy Electricity and Electronics Training Series (NEETS), Module 18, Radar
Principles, NAVEDTRA 172-18-00-84, Naval Education and Training
Program Development Center, Pensacola, FL, 1984.
Chapter 2
A1-F18AC-744-100, Forward Looking Infra Red (FLIR) System, Chapter 3,
Principles of Operation (0801-LP-020-9610)
OP 3541, Volume 1, Revision 2, AN/SPG-51D (0610-LP-354-1129)
OP 4350, Transmitter, Control and Power Supply for AN/SPG-51D
SE213-UE-MMO-010, Radar Set AN/SPS-48E; Volume 1 Part 1, Radar set,
Chapter 1, General Information (0910-LP-586-4200)
SE213-VC-MMO-010, Radar Set AN/SPS-52C; TM Volume 1, Chapters 1 and 2
(0910-LP-064-5800)
SW221-JO-MMO-010, Close-In Weapon System, Mk 15, Mod 11-14
(PHALANX); Introduction to CIWS, Volume 1 (0640-LP-167-5800)
AI-1
SW230-AO-SOM-060, Target Acquisitioning System (TAS) Mk 23; Operations
Manual for CV/CVN class, Integrated with CDS (0640-LP-168-1900)
SW261-SA-GYD-010, Ship Self Defense System (SSDS); Mk 1 Mod 0,
Installation and Checkout Support Guide (0640-LP-021-6420)
SW272-AM-AEG-010, AEGIS RADAR SYSTEM for SPY-1D; Description,
Operation and Maintenance (0640-LP-013-4590)
SW272-AJ-AEG-020, AEGIS RADAR SYSTEM HANDBOOK for SPY-1B/D; B/L
5.3/3A (0640-LP-021-7570)
SW279-EJ-AEG-010, AEGIS ANTENNA GROUP for SPY-1D; Description and
Operation (0640-LP-013-4490)
TE660-AX-PDD-230, AN/SYS-2 (V) 1 Radar Satellite Simulation Program;
P rog ra m D e s c r i p t i o n D o c u m e n t , Vo l u m e 2 3 ; A N / S P S - 4 8 E
(0910-LP-148-2900)
TW210-AA-GYD-010, Thermal Imaging Sensor System (TISS); AN/SAY-2;
Installation and Checkout Support Guide (0910-LP-017-6120)
TW271-T2-IDS-010, MK 92 Mod 2 Combined Antenna System
(0910-LP-019-9580)
Chapter 3
Department of Defense Directive 4715.1, “Environmental Security,” February 24,
1996.
Department of Defense Instruction 6055.11, “Protection of DoD Personnel from
Exposure to Radiofrequency Radiation and Military Exempt Lasers,”
February 21, 1995.
Electromagnetic Radiation Hazards (Hazards to Ordnance), NAVSEA OP 3565,
Volume II, Naval Sea Systems Command, Washington, DC, April 1995.
Electromagnetic Radiation Hazards (Hazards to Personnel, Fuel, and Other
Flammable Material), NAVSEA OP 3565, Volume I, Naval Sea Systems
Command, Washington, DC, 1979.
Executive Order, 12196, “Occupational Safety and Health Programs for Federal
Employees,” February 26, 1980.
Contributing Commands/Facilities
Commander Operational Test and Evaluation Force (COMOPTEVFOR), Surface
Warfare Division, Code 70
FC “A” School
Naval Air Warfare Center (NAWC) Weapons Division, Point Mugu
Naval Air Warfare Center Weapons Division (NAWCWD), Fleet Help Desk, China
Lake
Naval Research Laboratory (NRL)
Naval Sea Systems Command (NAVSEASYSCOM) NAVY SEA Test and
Evaluation Office
AI-2
Naval Surface Warfare Center, Carderock Division (NSWCCD) Smart Ship
Program
Naval Surface Warfare Center, Dahlgren Division (NSWCDD)
Surface Warfare Officer School (SWOS)
AI-3
INDEX
A
Accelerometers, 1-16
Acquisition, 1-18, 2-15
Acquisition phase, 1-19, 2-15
Active homing, 1-17
Air-search radar, 1-12, 2-1
AN equipment indicator system, 1-12
AN/ZPG-51 Radar, 1-21
AN/ZPG-60 radar, 1-21, 2-6
AN/ZPG-62 radar, 1-21, 2-6
AN/SPQ-9 antenna, 1-21, 2-7
AN/SPS-48, radar, 1-21, 2-2
AN/SPS-52 radar, 1-21, 2-1
AN/SPY-1 radar, 1-22, 2-4
Antenna lenses, 1-9
Antenna system, 1-7
array types, 1-10
feedhorns, 1-9
horn radiators, 1-9
lens antenna, 1-9
parabolic reflectors, 1-8
Array antennas, 1-10
Atmospheric conditions, 1-5
Detection, 1-19, 2-15
acquisition and tracking, 1-19
guidance (missiles), 1-16
launcher/gun positioning, 2-16
prediction, 1-19
Detection, 1-19, 2-15, 2-18
Dielectric (delay) lens, 1-9
Dielectric material, 1-9
Displays, 1-6
type A, 1-6
type B, 1-6
type E, 1-6
type P, 1-7
Doppler effect, 1-4
Dry air systems, 1-11
Ducting effect, 1-5
Duplex, 1-4, 1-6
E
Electromagnetic radiation, 3-1
Engaging, 2-19
Evaluation, 1-20
F
B
Basic radar systems, 1-1, 1-5
Beam deflection, 1-10
Beam-rider guidance, 1-16
Beam-riding missile, 1-16
Bearing, 1-3
Bearing resolution, 1-5
Boost phase, 1-14
C
Cathode-ray tubes (CRTs), 1-3, 1-6, 3-15
Close-in weapon system (CIWS), 1-11, 1-22, 2-10
Combined antenna system (CAS), 1-21, 2-10
Conducting (acceleration) lens, 1-9
Continuous wave illumination (CWI), 1-4, 1-11
Control group, 1-11
Control systems, missile, 1-14
D
Designation phase, 1-18
Detect-to-engage sequence, 1-19, 2-15
Feed horns, 1-9
Fire-control problem, 1-19
detect to engage sequence, 1-19, 2-15
Fire-control radar, 1-21, 2-3
Forward looking infra-red radar (FLIR), 1-22
Frequency-modulated continuous wave (FM-CW),
1-4
G
GMFCS, 1-20
Guidance (missiles), 1-14, 1-20
phases, 1-14
types of, 1-16
Guided missile fire control system, 1-14
Gyroscopes, 1-11
H
HARPOON missile, 1-14, 1-17
Hazards of electromagnetic radiation to fuels (HERF),
3-3
Hazards of electromagnetic radiation to ordnance
(HERO), 3-2
INDEX-1
Hazards of electromagnetic radiation to personnel
(HERP), 3-3
permissible exposure limit (PEL), 3-4
permissible exposure time (PET), 3-5
specific absorption rate (SAR), 3-3
High frequency surface wave radar, 1-22, 2-14
HOJ mode, 1-18
Home-on-jamming, 1-18
Homing guidance, 1-16
active, 1-17
passive, 1-18
semiactive, 1-17
Horizontal plane, 1-2, 1-11
Horn radiators, 1-8, 1-9
Mk 92 combined antenna system (CAS), 1-10, 1-19,
1-21, 2-9
Mk 92 fire control system, 1-21
Mk 95 radar, 1-21, 2-9
Mk 99 missile fire control system, 1-21, 2-4
Moving target indicator (MTI), 1-6, 2-2
Multi-dimensional radar, 1-13
Multi-function radar, 2-14
I
P
Inertial guidance, 1-16
Infrared search and track (IRST), 2-14
Initial phase, 1-14
Intermediate frequency (IF), 1-6
Parabolic reflectors, 1-8
Passive homing, 1-18
Phases of missile guidance, 1-14
initial (boost), 1-14
midcourse, 1-15
terminal, 1-15
Phases of radar operation, 1-18
acquisition, 1-15
designation, 1-18
track, 1-18
Plan position indicator (PPI), 1-7
Planar array antenna, 1-10
Prediction, 1-19
Pulse modulation, 1-4
Pulse-repetition frequency (PRF), 1-3
Pulse-repetition rate (PRR), 1-3
O
Optical sighting system (OSS), 1-22
Optronics systems, 1-22; 2-14
thermal imaging sensor system (TISS), 1-22, 2-14
J
Jamming, 1-18
JETDS, 1-12
Joint Army-Navy nomenclature system, 1-12
Joint electronics type designation system, 1-12
Joint-service standardized classification system, 1-12
L
Lens antenna, 1-9
R
M
Man aloft, 3-9
Maximum range, 1-3
Midcourse phase, 1-15
Minimum range, 1-3
Missile axes, 1-14
Missile guidance radar, 1-14
Mk 7 Aegis fire control system, 2-4
Mk 23 target acquisitioning system (TAS), 1-10, 1-21,
2-8
Mk 34 gun weapon system, 1-22, 2-4
Mk 45 light weight gun, 1-21, 2-7
Mk 74 fire control system, 1-21
Mk 75 light weight gun, 1-21, 2-9
Mk 86 gun fire control system (GFCS), 1-10, 1-21,
2-4, 2-6
Mk 91 fire control system, 1-21, 2-5, 2-9
Radiation hazard zones, shipboard, 3-7
Radar safety, 3-2
cathode-ray tubes (CRTs), 3-15
HERF, 3-3
HERO, 3-2
HERP, 3-3
RFR hazards, 3-12
x-ray emissions, 3-17
radioactive electron tubes, 3-15
warning signs, 3-11
working aloft, 3-9
Radar system block diagram, 1-5
antenna, 1-8
control group, 1-11
display, 1-6
duplexer, 1-6
radome, 1-10
INDEX-2
receiver, 1-6
stable element, 1-11
support systems, 1-11
synchronizer, 1-6
transmitter, 1-6
Radar guidance beam, 1-16
Radar measurements, 1-2
altitude, 1-3
bearing, 1-3
range, 1-3
Radar operation, 1-5, 2-7, 2-15
phases of, 1-18, 2-7
Radar system accuracy, 1-4
atmospheric conditions, 1-5
bearing resolution, 1-5
other factors, 1-5
range resolution, 1-5
Radar transmission methods, 1-4
continuous wave, 1- 4
pulse modulation, 1-4
Radomes, 1-10
Range, 1-3
minimum range, 1-3
maximum range, 1-3
range accuracy, 1-3
Range accuracy, 1-3
Range resolution, 1-5
Receiver, 1-6
Receiver recovery time, 1-6
Reference coordinate terms, 1-1
Reflected power, 1-10
Reflectors, 1-8
Relative bearing, 1-3
Remote optical sighting system (ROS), 1-22
RF, 1-3
RF interference, 1-18
RFR hazards, 3-12
burns, 3-7
eyes, 3-7
shipboard radiation hazard zones, 3-7
skin, 3-5
testicles, 3-7
Secondary effects, 1-10
Semi-active homing, 1-17
SSDS Mk 1 (Ship Self-Defense System), 1-22, 2-5,
2-9, 2-12, 2-13
Stable elements, 1-11
STANDARD ARM (missiles), 1-18
STANDARD SM-1, 1-14, 1-17, 1-21
STANDARD SM-2 missiles (MR & ER), 1-14, 1-17,
1-22, 2-5
STIR (Separate Target Illuminating Radar), 1-19,
1-21, 2-10
Support systems, 1-11
Surface angular measurements, 1-2
Synchronizer, 1-6
T
Temperature inversion, 1-5
Terminal phase, 1-15
Thermal imaging sensor system (TISS), 1-22, 2-14
Three-dimensional (3-D) radar, 1-12, 1-14
Track phase, 1-18
Tracking, 1-19, 2-19
Tracking radar, 1-18
Transmission lines, 1-7
Transmission loss, 1-10
Transmitter, 1-6
True bearing, 1-2
Types of guidance, 1-14
Types of radar, 1-12
W
Warning signs, 3-11
high voltage, 3-11
RF, 3-12
stack gas, 3-12
Waveguide, 1-7
Working aloft, 3-9
check sheet, 3-9
safety harness, 3-10
WSN-2, 1-11
WSN-5, 1-11
S
X
Safety harness, 3-10
Search radar, 1-21, 2-1
SEASPARROW missile system, 1-14, 1-17, 1-22, 2-9
X-ray emissions, 3-17
INDEX-3
Assignment Questions
Information: The text pages that you are to study are
provided at the beginning of the assignment questions.
ASSIGNMENT 1
Textbook Assignment: “Introduction to Basic Radar Systems,” chapter 1, pages 1-1 through 1-23 and
“Fire-Control Radar Systems,” chapter 2, pages 2-1 through 2-11.
1-6. What is the most common method used to
transmit radar energy?
NOTE: IN THIS ASSIGNMENT, FIGURES
MENTIONED IN THE QUESTIONS ARE FOUND
IN THE TEXT.
1-1.
1.
2.
3.
4.
The term “radar” is an acronym made from the
words
1.
2.
3.
4.
radio, detection, and roaming
radio, distance, and ranging
radio, detection, and ranging
radio, detection, or ranging
1-7. What characteristic of continuous-wave radar
makes it difficult, if not impossible, to get
accurate range measurements?
1.
2.
3.
4.
1-2. Radar surface angular measurements are
normally made from which direction?
1.
2.
3.
4.
North/south
East/west
Counter-clockwise from true north
Clockwise from true north
1. Separate objects at the same range, but
slightly different bearings
2. Distinguish between two targets on the
same bearing, but at slightly different
ranges
3. Separate objects at different ranges, but
slightly different bearings
4. Distinguish between two targets on
different bearings, but at the same range
True bearing/azimuth
True horizontal plane
Line-of-sight range
True north
1-4. What is the primary limiting factor for
maximum range of a pulse-radar system?
1.
2.
3.
4.
1-9. Which of the following factors affect(s) radar
performance?
Carrier frequency
Peak power of transmitted pulse
Receiver sensitivity
Pulse-repetition frequency
1.
2.
3.
4.
1-5. The angle between the centerline of the ship
and a line pointed directly at a target is known
by what term?
1.
2.
3.
4.
Doppler effect
Missile guidance
Illumination
No specific stop time
1-8. Range resolution is defined as the ability of a
radar to perform what action?
1-3. The angle measured clockwise from true north
in the horizontal plane defines which of the
following terms?
1.
2.
3.
4.
Continuous-wave
Pulse-modulation
Doppler-wave
Frequency-modulation
Operator skill
Electronic Attack activity
Weather conditions
All of the above
1-10. According to figure 1-4, what is considered
the heart of a pulse radar system?
Relative bearing
True bearing
Angle north
Angular bearing
1.
2.
3.
4.
1
Synchronizer
Antenna system
Transmitter
Duplexer
1-11. A certain amount of time is required for a
duplexer to disconnect the antenna from the
receiver and connect it to the transmitter.
What is this switching time called?
1.
2.
3.
4.
1-17. Which of the following design actions can be
used to eliminate feedhorn shadows?
1. Making the horn smaller
2. Putting the horn behind the reflector
3. Offsetting the horn from the center of the
reflector
4. Making the reflector smaller
Receiver recovery time
Fast reaction time
Detection time
Transmitter recovery time
1-18. Which of the following antennas are lens type
antennas?
1-12. What radar subsystem is used to convert RF
echoes to a lower frequency?
1.
2.
3.
4.
1.
2.
3.
4.
Superheterodyne receiver
Antenna system
Duplexer
Transmitter
1-19. In a delay lens, the amount of delay is
dependent on what characteristic?
1-13. Figure 1-5 shows four basic radar displays.
Which of the displays uses your own ship as
the center of the display?
1.
2.
3.
4.
1.
2.
3.
4.
Type A
Type B
Type P
Type E
1.
2.
3.
4.
Truncated
Parabolic
Orange peel
Banana peel
Slots
Dipoles
Horns
Each of the above
1-21. In an array antenna, what determines the
position of the beam?
1-15. Radar antennas are designed using wellknown optical design techniques. Which of
the following radar characteristics allows a
radar antenna to be designed in this way?
1. The relative phase between the elements
2. The relative amplitude between the
elements
3. The total amplitude of the elements
4. The scan motor
1. Radar operates in the microwave region of
the electromagnetic spectrum
2. Radar operates in the ultraviolet region of
the electromagnetic spectrum
3. Radar operates in the VLF region of the
electromagnetic spectrum
4. Radar operates in the infrared region of the
electromagnetic spectrum
1-22. Which of the following adverse effects in a
small radome is caused by reflected power?
1.
2.
3.
4.
Beam deflection
Transmission loss
Antenna mismatch
Secondary effects
1-23. What level of maintenance do FC’s normally
perform on radomes?
1-16. What general characteristic of a horn radiator
is determined by the size of its mouth
opening?
1.
2.
3.
4.
Thickness
Dielectric constant
Angle of reflection
Angle of incidence
1-20. Which of the following elements can be used
in an array antenna?
1-14. An automobile headlight is similar, in shape,
to what type of radar reflector?
1.
2.
3.
4.
Conducting and dielectric
Optical and electro-optical
Flatplane and spherical plane
Microwave and plane wave
1.
2.
3.
4.
Symmetry
Relativity
Conductivity
Directivity
2
Ship’s 2M
Factory repairs
Technical repairs
Preventive maintenance
1-24. Which of the following equipment is NOT part
of the control group for a radar system?
1.
2.
3.
4.
1-30. Missile guidance systems consist of two
separate systems. An attitude control system
is one of those systems. What is the other
system?
AN/UYK-43 computer
AN/BPS-15 radar group
RD-358A(V)/UYK magnetic tape unit
OJ-535 data terminal set
1.
2.
3.
4.
1-25. Every radar system requires a certain amount
of support equipment to operate properly.
Which of the following equipment is support
equipment?
1.
2.
3.
4.
1-31. According to figure 1-17 which of the
following components is NOT part of the
control subsystem?
SF6 gas canister
Step-down transformer
Frequency converter
Each of the above
1.
2.
3.
4.
1-26. What is the primary purpose of a stable
element?
1.
2.
3.
4.
1.
2.
3.
4.
AN/SPF-40
AN/SPS-48E
AN/SPG-60
AN/SPQ-9B
Standard SM-1 (ER)
Standard SM-1
Standard SM-2 (MR)
Standard SM-2 (ER)
1-34. The initial phase of a missile flight lasts how
long?
1.
2.
3.
4.
1-28. What is the primary function of air-search
radar?
To maintain a 360-degree surveillance
To provide security against attacks
To provide information for aircraft control
To determine aircraft altitude
Until the target is destroyed
Until the booster recharges
Until the booster burns up its fuel
Until the target manuevers
1-35. What is unique about the Harpoon missile
guidance phase?
1. It is the shortest phase, in both time and
distance
2. It is the longest phase, in time only
3. It is the longest phase, in distance only
4. It is the longest phase, in both time and
distance
1-29. The AN/SPY-1 series radar is a multidimensional radar. How does it differ from
air-search radar?
1.
2.
3.
4.
Boost, dropoff, terminal
Boost, midcourse, terminal
Guided, midcourse, terminal
Unguided, midcourse, terminal
1-33. Which of the following missiles should follow
the guidance path shown in figure 1-18B?
1-27. What equipment listed below does NOT
comply with the Joint Electronics Type
Designation System (JETDS)?
1.
2.
3.
4.
Computer detector
Servo motor
Receiver
Control surface
1-32. The Standard SM-2 missiles use three phases
of guidance. What are they?
1. To measure any deviation of a director
from the vertical plane
2. To measure approximate deviation from
any optical equipment
3. To measure any deviation of a launcher
from the horizontal plane
4. To measure approximate deviation from
any radar antenna
1.
2.
3.
4.
Rocket motor control system
Rocket motor thrust system
Flight yaw control system
Flight path control system
It has a wider vertical beamwidth
It has a narrower vertical beamwidth
It has a lower transmitting frequency
It has a lower output power
1-36. What phase of missile guidance requires fast
response to guidance signals?
1.
2.
3.
4.
3
Final phase
Boost phase
Initial phase
Midcourse phase
1-37. In an inertial guidance system, what devices
control the missile?
1.
2.
3.
4.
1-44. Which of the following is the correct sequence
for modes of radar operation?
Accelerometers
Accelerators
Fin stabilizers
Yaw stabilizers
1.
2.
3.
4.
1-38. A beam-rider missile is most effective against
which of the following types of targets?
1.
2.
3.
4.
1-45. Search radar is used for what operation of the
fire-control problem sequence?
Outgoing and long-range
Incoming and long-range
Incoming and medium-range
Outgoing and long-range
1.
2.
3.
4.
1-39. Homing guidance is the most accurate method
of missile guidance. What gives it this ability?
1.
2.
3.
4.
Track phase
Detection
Prediction
Evaluation
1-46. Continuous, accurate target position is
available during what stage of fire-control
problem sequencing?
RF waves
Reflected energy
Magnetic field energy
Guidance error signals
1.
2.
3.
4.
1-40. According to figure 1-21, which of the
following terms best describes guidance for a
HARPOON missile?
Acquisition and tracking
Launcher positioning
Missile guidance
Evaluation
1-47. Which of the following operations is NOT
performed after target detection and
acquisition?
1. Passive homing
2. Semi-active homing
3. Active homing
1.
2.
3.
4.
1-41. Which of the following factors is a drawback
of semi-active homing?
Establishing a track LOS
Determining launcher position angle
Positioning the gun mount
Establishing a targets initial position
1-48. During the acquisition and tracking phase,
why are radar indications of a target
considered as instantaneous, present target
positions?
1. During its use, the ship is not free to use
SMS missiles
2. Its use keeps the system tied to a single
target
3. It can only be used with SEASPARROW
missiles
4. It can only be used with STANDARD
SM-1 missiles
1.
2.
3.
4.
1-42. Figure 1-21 illustrates the different homing
guidance methods. Which method is used for
a STANDARD ARM missile?
RF energy travels at the speed of light
Target ranges are relatively small
Both 1 and 2 above
Target speed is fast
1-49. According to Table 1-2, which of the
following radar systems should be used during
the designation phase of the fire-control
problem sequence?
1. Passive homing
2. Semi-active homing
3. Active homing
1.
2.
3.
4.
1-43. What type of data is primarily used in
fire-control radar?
1.
2.
3.
4.
Designation, acquisition, and search
Designation, direction, and search
Designation, direction, and track
Designation, acquisition, and track
Continuous positional data
Intermittent horizontal data
Target resolution data
Continuous ship position data
4
Mk 95 radar
52C
Mk 1
HF Surface Wave
1-50. During the acquisition and tracking phase, a
fire control radar director is aligned with the
search radar’s target position. Which of the
following radar systems should be used as the
fire control radar in this process?
1.
2.
3.
4.
1-56. The AN/SPS-48 radar is found on what type(s)
of ship?
1.
2.
3.
4.
SPY 1 Series
SPS 48E
SPS 52C
FLIR
1-57. Fire-control radar is normally part of larger
systems. Which of the following systems are
larger gun or missile systems that are
associated with fire-control radar?
1-51. Although fire-control radar is more accurate,
initial detection of a target is done with search
radar. Which of the characteristics listed
below enable(s) search radar to initially detect
a target?
1.
2.
3.
4.
1.
2.
3.
4.
Narrow beam width
Wide beam width
Long-range 360 degree coverage
Both 2 and 3 above
1.
2.
3.
4.
AN/SPS-40(V)
SLQ-32(V)3
AN/SPS-49
AN/SPS-48E
1.
2.
3.
4.
1. It provides access for preventive
maintenance
2. It enables four modes of operation
3. It enables solar alignment
4. It provides high-elevation coverage
SSDS
SPY-1
Mk 92
CAS
1-60. What radar system is the heart of the AEGIS
system?
1-54. The AN/SPS-48E radar is a long-range, threedimensional radar that FC’s work with. How
does this radar provide contact range, height,
and bearing information?
1.
2.
3.
4.
By using D/E band frequency scanning
By using E/H band short-dwell time
By using E/F band frequency scanning
By using D/E band short-dwell time
SSDS
AN/SPY-1 radar
MFCS
GFCS
1-61. In reference to figure 2-6, which of the
following is NOT a weapon or sensor found
on an AEGIS class cruiser?
1.
2.
3.
4.
1-55. Which of the following modes is NOT an
SPS-48 radar mode?
1.
2.
3.
4.
SPY-1 radar system
Mk 99 MFCS
Mk 86 GFCS
All of the above
1-59. The Mk 7 Aegis FCS is found on board
ARLEIGH BURKE class destroyers and
TICONDEROGA class cruisers. Which of the
following radar systems should you find on
board one of these ships?
1-53. What is the function of the 25-degree tilt in the
AN/SPS-52 radar antenna?
1.
2.
3.
4.
GFCS
FCCS
GMCM
MFCC
1-58. Which of the following systems is/are found
on board the USS Paul Hamilton?
1-52. Which system below is a search radar that an
FC might work with in today’s Navy?
1.
2.
3.
4.
NIMITZ class carriers
LCC class amphibious ships
ENTERPRISE class carriers
All of the above
Equal Angle Coverage
Maximum Frequency Management
Maximum Energy Management
Adaptive Energy Management
5
AN/SPS-49 radar
Mk 41 vertical launching tubes
AN/SPS-40E radar
AN/SPG-62 illuminators
1-62. The Mk 99 MFCS provides terminal guidance
control for which of the following missiles?
1.
2.
3.
4.
1-69. The AN/SPQ-9B radar is found on board
which of the following ship types?
TOMAHAWK cruise missile
SM-2 anti-air missile
SM-1 extended range missile
Stinger missile
1.
2.
3.
4.
1-63. What type of radar is the AN/SPG-62?
1.
2.
3.
4.
1-70. The Mk 23 TAS integrates various
subsystems. Which of the following
subsystems is NOT part of that integration?
Long-range search radar
Short-range tracking radar
Missile guidance radar
Gun illumination radar
1.
2.
3.
4.
1-64. Which of the following weapons is controlled
by the Mk 86 GFCS?
1.
2.
3.
4.
1.
2.
3.
4.
CAS and Mk 23 TAS
STIR and CAS
AN/SPG-9B and AN/SPQ-9A
AN/SPQ-9 and Mk 23 TAS
1.
2.
3.
4.
Real-time signal and data processing
Low resolution and narrow beam radar
Raw video and azimuth video reference
Variable-time signal and beam processing
1.
2.
3.
4.
Mk 95 illuminator
Mk 23 target acquisition system
Mk 157 discriminator
AN/SPQ-9 series radar
1-74. Which of the following ship classes uses the
Combined Antenna System?
Air, surface, and beacon
Air, surface, and beam
Detection and acquisition
High scan and low scan
1.
2.
3.
4.
1-68. What mode of the AN/SPQ-9B radar uses the
pulse-doppler radar?
1.
2.
3.
4.
Firing officer console only
Signal data processor console only
Radar set console only
Advanced display system console
1-73. Which of the following radar systems is NOT
part of the Mk 91 fire control system?
1-67. What modes of operation does the
AN/SPQ-9B have?
1.
2.
3.
4.
SEASPARROW missile
Mk 45 gun
HARPOON missile
Close-in weapon system
1-72. The Mk 91 missile fire control system uses
which of the following consoles?
1-66. The AN/SPQ-9B radar can track air and
surface targets simultaneously. What
characteristics allow it to do this?
1.
2.
3.
4.
Two-dimensional air-search radar
Long-range threat evaluation console
IFF subsystem
Display subsystem
1-71. What is the primary weapon controlled by the
Mk 91 missile fire control system?
Mk 45 5-inch gun
Mk 75 3-inch gun
Mk 13 missile launcher
Mk 45 8-inch gun
1-65. Which of the following radar systems enable
the Mk 86 GFCS to support AW gun
engagements?
1.
2.
3.
4.
SPRUANCE class destroyers
TICONDEROGA class cruisers
SAN ANTONIO class amphibious ships
All of the above
TICONDEROGA class cruisers
LHA class amphibious ships
PERRY class frigates
SEAWOLF class submarines
1-75. In reference to figure 2-14, where is the STIR
antenna located on a PERRY class frigate?
Surface
Detection
Air
Beam
1.
2.
3.
4.
6
On the forward bullnose
On the aftship O-2 level
On the forecastle main deck
On the midship O-2 level
ASSIGNMENT 2
Textbook Assignment: “Fire Control Radar Systems,” chapter 2, pages 2-11 through 2-20 and “Radar Safety,”
chapter 3, pages 3-1 through 3-18.
2-1. The Mk 15 Phalanx Close-In Weapon System
has two primary modes of operation. What are
they?
1.
2.
3.
4.
2-6. Which of the following systems uses heat or
light as a source for target detection?
1.
2.
3.
4.
Autonomic and manual
Recommend fire and manual
Remote control and manual
Automatic and manual
2-7. The Thermal Imaging Sensor System (TISS)
provides surface and air target data to combat
systems via an electro-optical system. TISS
also has which of the following capabilities?
2-2. What is the principal air threat to U. S. naval
surface ships?
1. Anti-ship cruise missiles
2. Low, slow, or hovering aircraft
3. Low altitude enemy aircraft
1.
2.
3.
4.
2-3. The Ship Self-Defense System (SSDS)
integrates and coordinates what equipment on
board non-AEGIS class ships?
1.
2.
3.
4.
2-4.
Good night detection and identification
Mine detection
Both 1and 2 above
Aid to navigation
2-8. Which of the following sensors is/are a part of
upcoming developments in radar?
Existing sensors and weapons
Special computer programs
Operator stations
All of the above
1.
2.
3.
4.
SSDS is the integration element of the entire
combat system program, including all
weapons and sensors. Which of the following
is NOT a purpose of SSDS?
High frequency surface wave
Multi-function radar
Volume search radar
All of the above
QUESTIONS 2-9 THROUGH 2-19 REFER TO THE
DETECT-TO-ENGAGE SCENARIO.
2-9. What is the definition of a warning status of
yellow?
1. To improve reaction time from detect to
engagement in less than 60 seconds
2. To improve the performance of
weapons/sensors beyond normal
stand-alone capability.
3. To improve the integration and
coordination of all weapons and sensors in
order to provide quick reaction combat
capability
4. To improve the capability to engage
multiple targets and quick response against
anti-ship cruise missiles
1.
2.
3.
4.
Hostilities probable
Hostilities imminent
Hostilities detected
Hostilities displayed
2-10. The Tactical Action Officer (TAO) is
responsible for which of the following actions
in the absence of the commanding officer?
1. The proper employment of the ship’s
weapons systems
2. The proper navigation of the ship through
friendly waters
3. The proper employment of the ship’s
auxiliary systems
4. The proper use of consoles in the combat
information center
2-5. Which of the following systems is an SSDS
interface on a non-AEGIS class ship?
1.
2.
3.
4.
Fire control radar
Close-in weapon system
Optronic system
Air search radar
AN/SPS-49 air search radar
AN/SPG-62 illuminator
AN/SPQ-9B fire control radar
AN/SPY-1 multi-dimensional radar
7
2-11. During a Detect-to-Engage scenario, what is
the first equipment to detect and identify a
threat?
1.
2.
3.
4.
2-16. Once a target is close enough to be detected by
your weapons system, the fire control
computer uses the target’s course and speed to
compute where your missile will engage the
target. What is the term used for this place of
engagement?
A wide band ESM receiver
A fire control radar
An IFF interrogator
A narrow band navigation radar
1.
2.
3.
4.
2-12. The ship’s 2-D air search radar, with the help
of the ESM receiver, helps to localize the
incoming threat. What tactical information
does localizing the threat give you?
1.
2.
3.
4.
2-17. What verbal command authorizes the
launching of a missile at a hostile target?
An accurate bearing only
An accurate range and bearing
An accurate range only
An accurate range, bearing, and altitude
1.
2.
3.
4.
2-13. What feature of the ship’s 3-D radar leads you
to believe that the threat consists of only one
aircraft?
1.
2.
3.
4.
Ship’s lookouts
Ship’s sensors
Anti-air warfare commander
ESM equipment only
2-19. Which of the following functions is part of the
modern fire control problem?
2-14. According to the Rules of Engagement (ROE)
in effect, you have determined hostile intent
based on a target’s action. At this point you
should prepare to defend your ship against
what type of attack?
1. Informing the warfare commander of the
threat
2. Confirming target resolution
3. Making a weapon selection
4. Making equipment ready for tracking
Probable
Conceivable
Comprehensible
Imminent
2-20. What is the ultimate goal of all subsystem
components in solving the fire control
problem?
1.
2.
3.
4.
2-15. After you inform the Anti-Air Warfare
Commander of a target’s hostile intent, he
places your ship in Air Warning Red. What
does Air Warning Red mean?
1.
2.
3.
4.
“Batteries release”
“Batteries charged”
“Fire all batteries”
“Fire all weapons”
2-18. From which of the following sources do you
confirm that the target has been destroyed or
neutralized?
1. The bearing resolution of the
pulse-compressed radar
2. The elevation resolution of the
pulse-compressed radar
3. The resolution of the ESM sensors
4. The range resolution of the
pulse-compressed radar
1.
2.
3.
4.
Predicted engagement envelope
Predicted intercept envelope
Predicted intercept point
Predicted engagement point
To quickly locate the target
To neutralize the target
To detect the target
To select the right weapon
2-21. There are three phases involved in target
detection by a weapon system. What is the
second phase?
Attack is imminent
Attack is probable
Attack is on hold
Attack is in progress
1. Surveillance and detection
2. Interpret the behavior of the target
3. Measuring or localizing the target’s
position
4. Classifying the target
8
2-22. Which phase uses either reflected energy or
received energy emitted from the target to
detect a target?
1.
2.
3.
4.
2-27. What is at the functional center of every
weapon system?
1.
2.
3.
4.
First
Second
Third
Fourth
2-28. What is the purpose of your command’s
bombarding you with safety slogans, rules,
and procedures?
2-23. In tracking a target, a collection of motors and
position-sensing devices called a servo system
helps to successfully engage a target. The
operation of such a system is based on what
inherent concept?
1.
2.
3.
4.
1.
2.
3.
4.
Error reduction
Feedback
Zeroing
Rate reduction
1. True
2. False
1. The difference between where the sensor is
located and where the target is going
2. The difference between where the target is
pointing and where the target is actually
going
3. The difference between where the sensor is
pointing and where the sensor is located
4. The difference between where the sensor is
pointing and where the target is actually
located
2-30. Radio Frequency Radiation (RFR) is one of
the hazards associated with radar operation.
Which of the following areas around a radar
antenna should you consider to be an RFR
hazard?
1.
2.
3.
4.
The front
The sides
The rear
All of the above
2-31. If you suspect any injury or excessive
exposure to radiation which of the following
individuals should you contact?
2-25. What devices are used in servo systems to
detect the position of and to control the
movement of power drives?
1.
2.
3.
4.
Gun mounts
Missile launchers
Optical encoder
Radar antennas
Your leading petty officer
Your ship’s doctor or corpsman
Your division chief
All of the above
2-32. Whenever you work around radar equipment,
you should observe which of the following
safety precautions?
2-26. The effective engagement and neutralization
of a target requires that a destructive
mechanism, such as a missile warhead, be
delivered to the vicinity of the target. Which
of the following factors should be considered
in the design of an effective destructive
mechanism?
1.
2.
3.
4.
To keep you alive and well
To improve your morale
To keep you busy
To give you something to do
2-29. Being safety conscious means to approach
every job from a safety point of view.
2-24. What is the definition of “system error”?
1.
2.
3.
4.
A human being
A complex computer
A large RF power supply
A planned maintenance system
1. Do not inspect feedhorns when they are
emitting RFR
2. Observe all RADHAZ warning signs
3. Ensure that radiation hazard warning signs
are available and used
4. All of the above
Propulsion system
Fuzing mechanism
Warhead design
All of the above
9
2-33. Scientific studies have shown that people
cannot easily sense electromagnetic radiation
(EMR). What EMR frequency range presents
a hazard to humans?
1.
2.
3.
4.
2-39. Who is responsible for the implementation of
HERO requirements?
1.
2.
3.
4.
10 Hz to 300 Hz
10 kHz to 300 GHz
10 THz to 300 THz
1000 Hz to 3000 Hz
2-40. Which of the following publications lists
specific guidance about fueling operations and
radar on your ship?
2-34. Hazards of Electromagnetic Radiation to
Ordnance (HERO) is one category of radiation
hazards. What are the other two categories?
1.
2.
3.
4.
1. EXCON bill
2. NAVSEA OP 3565
3. NAVELEX volume I
HERP and HERD
HERF and HERR
HERD and HEED
HERP and HERF
2-41. According to table 3-1 in the text, what is the
maximum permissible exposure time limit for
a fixed-beam hazard with the AN/SPY-1 radar
transmitter?
2-35. What type of devices can actuate prematurely
in ordnance systems due to RFR?
1.
2.
3.
4.
1.
2.
3.
4.
Electro-optical devices
Electromagnetic devices
Electroexplosive devices
Electromechanical devices
During loading only
During unloading only
During assembly
During disassembly only
1. A decrease in frequency only
2. An increase in frequency only
3. Either an increase or decrease in frequency
2-43. A navigational radar with a frequency of 900
MHz may cause what type of damage, if any,
to body tissues?
2-37. The radiation hazard HERO can be broken
down into three classifications. In which of
the following conditions is an item considered
to be HERO unsafe?
1.
2.
3.
4.
1.
2.
3.
4.
The item is being assembled
The item contains
The item is sufficiently shielded from
The item, through testing, has been proven
to be adversely affected by
Minor damage
Damage to surface skin
Deep tissue damage
None
2-44. Which of the following parts of the
electromagnetic spectrum can cause damage to
the transparent lens of the eye?
2-38. Which of the following publications will list
your ship’s specific requirements for HERO
safety?
1.
2.
3.
4.
0.023 minute
0.23 minute
3.2 minutes
6 minutes
2-42. Which of the following changes in frequency
increases the likelihood of biological damage
from RFR?
2-36. When are ordnance systems most susceptible
to RFR energy?
1.
2.
3.
4.
Commanding officer
Executive officer
Safety officer
All hands
1.
2.
3.
4.
Naval Sea Systems Command instruction
EMCON bill
NAVSEA OP 3565
NAVAIR 16-1-529
Ultraviolet
Infrared
Radio frequency
All of the above
2-45. Permanent injury to the testicles can happen
because of which of the following hazard
conditions?
1. An extremely high dosage of RF
2. High exposure of RF for many years
3. Both 1 and 2 above
10
2-46. Shipboard radar has cutout switches for
personnel safety due to radiation. Which of
the following is a function of cutout switches?
2-52. Which of the following is a danger associated
with static charges encountered by personnel
working aloft?
1. They turn off the transmitter for certain
bearings and elevations
2. They turn off the transmitter for certain
bearings only
3. They turn off the transmitter for certain
elevations only
1.
2.
3.
4.
2-53. Because of the associated dangers, no one may
go aloft without the permission of which of
the following personnel?
2-47. The specific cutout zones for your radar are
identified in which of the following
publications?
1.
2.
3.
4.
1.
2.
3.
4.
NAVSEA OP 3565
Operational publications
DOD instruction 6055.11
Bureau of Medicine and Surgery
publications
1.
2.
3.
4.
Slow healing injury
Odor of scorched skin
A tingling sensation
Hair standing up
1.
2.
3.
4.
The location of the crane
Induced RFR voltage
The location of transmitters
The location of wire ropes
Commanding officer
Safety officer
Officer of the deck
Master chief of the command
2-56. How often should the announcement “DO
NOT ROTATE OR RADIATE ANY
ELECTRICAL OR ELECTRONIC
EQUIPMENT WHILE PERSONNEL ARE
WORKING ALOFT” be made over the 1MC?
2-50. The careful use of frequency can reduce the
RFR voltages induced into crane structures
and rigging. Which of the following is a
better approach for the prevention of RFR
induced voltage injuries to personnel?
1.
2.
3.
4.
1. The use of RFR high voltage insulator
links
2. The use of RFR personnel protectors
3. The use of RFR insulated gloves
4. The use of RFR cable
Every 15 minutes
Every 20 minutes
Every 30 minutes
Every 45 minutes
2-57. What document gives you specific instructions
for your ship with regard to man aloft
procedures?
1. Under way check off list
2. Master work list
3. Ship’s Organization and Regulation
Manual
4. Man Aloft Bill
2-51. Which of the following is considered the
greatest hazard associated with working aloft?
1.
2.
3.
4.
Working check sheet
Working aloft check sheet
Under way check off list
In port work list
2-55. When your ship is underway, who must grant
permission to go aloft?
2-49. A common source of RFR burns is crane
hooks. Which of the following factors is the
basis of these burns?
1.
2.
3.
4.
Chief petty officer
Officer of the deck
Division officer
Department head
2-54. Which of the following documents must be
properly completed before permission is given
to go aloft?
2-48. Which of the following is a symptom of a mild
burn?
1.
2.
3.
4.
RFR burns to the skin
High-voltage shock
Surprise of the shock may cause a fall
Electrical arcing
Dropping of objects
Asphyxiation from stack gasses
Electrical shock
Falling
11
2-58. Which of the following is NOT a general
guideline for going aloft?
2-63. Your radar equipment has a 4-inch red line
circling it. What type of sign should be posted
for your equipment?
1. Stop work if the ship rolls more than 10
degrees
2. Make sure the climber sleeve is attached to
a safety harness when the wind speed is in
excess of 30 knots
3. Read all posted safety placards before you
begin work
4. Wear personal protective gear for hazards
other than
1.
2.
3.
4.
2-64. A RADHAZ safety sign is mounted on a hook
insulator and warns personnel not to touch the
wire/rigging above the insulator. What type
of RADHAZ safety sign is it?
2-59. After working aloft, FC3 Smith leaves some
rags and tools unsecured and then goes to
lunch. You are his supervisor and learn that
the ship’s helo will be flying right after lunch.
What, if anything, should you be concerned
about, knowing the above facts?
1.
2.
3.
4.
Type 1
Type 2
Type 3
Type 4
2-65. Which of the following types of fuel is NOT
considered to have a HERF problem?
1. FOD
2. Rescheduling maintenance
3. Nothing
1. AVGAS
2. MOGAS
3. JP-5
2-60. For your safety when going aloft you should
wear an approved parachute type harness.
Which of the following components is/are
associated with this type of safety harness?
1.
2.
3.
4.
Type 1
Type 2
Type 3
Type 4
2-66. The type 6 RADHAZ sign advises of hazards
of electromagnetic radiation to ordnance.
Which of the following publications gives
guidance on type 6 signs?
Safety lanyard
Tending line
Double lock snap hooks
All of the above
1.
2.
3.
4.
2-61. A “Danger High Voltage” warning sign should
be posted at the entrance to compartments that
contain which of the following equipment?
EMCON bill
NAVSEA OP 3565
SORM
NAVSEA OP 4134
2-67. Which of the following instructions is NOT a
proper instruction concerning a CRT?
1. Equipment with shock hazards in excess of
30 volts
2. Equipment with shock hazards in excess of
500 volts
3. Equipment with exposed conductors with
shock hazards in excess of 500 volts
4. Equipment with exposed conductors with
shock hazards less than 30 volts
1. Discharge the high voltage from the anode
connector before removing the CRT from
its yoke
2. Wear safety glasses and gloves when
lifting the CRT by its neck
3. Always place CRT face down on a thick
piece of felt, rubber, or smooth cloth
4. Avoid scratching or striking the surface
2-62. In which of the following locations should you
post stack gas warning signs?
2-68. On a ship, each electronics space is supposed
to have one radioactive disposal spill kit.
Which of the following items should be in the
spill kit?
1. Near the bottom of each access ladder
leading aloft
2. At the top of each ladder leading aloft
3. At the base of the antenna pedestal
4. All of the above
1. A container, rubber gloves, and forceps
2. Masking tape, gauze pads, and a container
of water
3. Respirator, radioactive material stickers,
and procedures
4. All of the above
12
2-69. If an approved HEPA filtered vacuum is NOT
available for cleaning up the broken pieces of
a CRT, what is the approved alternate method
for clean up?
2-71. X-ray emissions can penetrate human tissue
and cause both temporary and permanent
damage. Which of the following types of
equipment are sources of x-rays?
1. Use forceps and a wet cloth with a firm
back and forth motion
2. Use forceps and dry cloth with a careful
patting motion
3. Use forceps and dry cloth with a circular
motion
4. Use forceps and a wet cloth, making one
stroke at a time
1.
2.
3.
4.
2-70. If you sustain a wound from a sharp
radioactive object whom should you
immediately notify?
1.
2.
3.
4.
Safety officer
Commanding officer
Medical officer
Officer of the deck
13
Magnetrons
Klystrons
CRTs
All of the above
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