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Purpose and Scope
This manual is a basic reference document for using the tactical
satellite (TACSAT) communications system. It does not replace technical
manuals for equipment or field manuals for signal tactical organizations.
The purpose of the manual is to translate doctrine and detailed technical
data into practical guidance for planning and operating a TACSAT
communications system. It provides guidance for deploying, controlling,
and managing TACSAT communications systems and terminals.
This manual includes a description of the TACSAT communications
equipment. It also provides instructions for its doctrinal use. This
doctrine provides a firm foundation of guidance to TACSAT communications
The intended users of this manual are operators/supervisors,
planners, and to some extent, maintainers. Operators/supervisors will
use the manual for basic instruction and as a guide on how to use the
equipment. Planners will use it for system and network planning.
Maintainers can use it as an adjunct to the technical manual and as a
quick reference when needed. To use this manual, the following references
are required: FM 24-18, TC 24-21, DCAC 800-70-1, TC 24-24, and TC 24-4A.
TC 24-4A contains all classified TACSAT communications data.
User Comments
The proponent of this publication is HQ TRADOC. Your comments on
this publication are encouraged. Submit changes for improving this
publication on DA Form 2028 (Recommended Changes to Publications and
Blank Forms) and key them to pages and lines of text to which they
apply. If DA Form 2028 is not available, a letter is acceptable. Provide
reasons for your comments to ensure complete understanding and proper
evaluation. Forward your comments to Commander, United States Army
Signal Center and Fort Gordon, ATTN: ATZH-DTL, Fort Gordon, Georgia
FM 24-11
Chapter 1
Army Space Activities
a. Tactical satellite (TACSAT) communications is part of a
larger group of Army space activities. The Chief of Staff, US Army (CSA)
directs all Army space activities through the Vice Chief of Staff, US
Army (VCSA). The VCSA is chairman of the Army space council. This group
recommends and guides the CSA in Army space-related activities such as
current and future space missions and the Army’s mission in the unified
United States Space Command (USSPACECOM). The Army space council is made
up of representatives from selected Army staff agencies, field operating
agencies, and major commands. A general officer from the United States
Army Information Systems Command (USAISC) is a member of the Army space
b. The Army Space Institute (ASI) and the United States Army
Space Command (USARSPACE) are the two Army organizations for space. The
ASI is a field operating agency of the United States Army Training and
Doctrine Command (TIWIOC). Missions include developing and integrating
space-related concepts and doctrine across mission areas. USARSPACE is
under the operational command of the USSPACECOM and will expand the
Army’s role in the operational aspects of space. USARSPACE missions
include operating the Regional Space Support Centers (RSSCS). These
centers provide the ground mobile forces (GMF) manager support for the
super high frequency (SHF) TACSAT segment and GMF control.
Military Requirements
a. Command, control, and communications (C ) is the key to
success in the AirLand Battle. Due to technological advances, greater
mobility, and the extended battlefield, radio communications is
paramount in the communications plan. However, while technology has
improved the equipment, communications has not kept pace. Two
limitations are the congested frequency spectrum and the physical limits
on radio wave propagation. The frequency required for long-range radio
adds to the frequency congestion problem. Requirements normally exceed
the available, useable frequencies. Frequency congestion and inherent
limitations of terrain and noise hamper short-range tactical radio.
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Coupled with the need for flexibility, security, and reliability, radio
communications remains a critical problem to the communicator.
b. TACSAT communications is the first radio system to
successfully overcome most of these limitations. Using an orbiting
satellite repeater illuminates one-third of the earth for direct line of
sight (LOS) operations. This makes it possible to establish tactical
communications on a scale never before accomplished. With more
frequencies available and a single station LOS relay to almost any point
on the battlefield, TACSAT equipment greatly enhances communications.
c. TACSAT communications is reliable, flexible, and survivable.
It can replace certain links previously provided by conventional LOS
radio relay, troposcatter, high frequency (HF) single sideband (SSB) or
frequency modulated (FM) radios. The tremendous bandwidth available and
computer switching makes a self-organizing communications network
feasible. TACSAT communications is not the answer to all communications
problems. However, a well thought-out, properly executed plan that
augments the traditional ground-based communications system with
appropriate TACSAT resources can improve communications availability,
reliability, and flexibility.
TACSAT Systems
a. TACSAT systems, like terrestrial systems, vary depending on
the communications requirements. Just as there is a need for both HF SSB
and very high frequency (VHF) FM radio in the tactical environment,
there is also a need for different satellite systems. The peculiarities
of mission requirements make it necessary to have different TACSAT
communications systems.
b The TACSAT communications systems of the US Army ground
forces operate in one of four categories.
(1) The Army Multichannel Satellite Communications System’s
terrestrial terminals are the AN/TSC-85( ) and 93( ). The Air Force
terminals are the AN/TSC-94A and the AN/TSC-100A. The satellites used
for interconnectivity of these multichannel terminals are Defense
Satellite Communications System (DSCS) IIs and DSCS IIIs. The frequency
range of this system is SHF (7.9-8.4 GHz for uplink and 7.25-7.75 GHz
for downlink.)
(2) The Special Communications System (SCS) is controlled and
managed by the ultra high frequency (UHF) Air Force Satellite
Communications System. The US Army ground terminals used in SCS are
AN/MSC-64(V) and AN/GSC-40(V). The frequency range of the system is UHF
(225-400 MHz) for up and downlink communications.
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(3) Authorized Army units use the AN/PSC-3, AN/VSC-7, AN/URC-101,
and AN/URC-110 for extended range communications. The frequency range of
the system is UHF (225-400 MHz) for up and downlink communications.
(4) When fielded, the AN/TSC-124 (known as, single-channel
objective tactical terminal (SCOTT)) will provide ground terminals for
special communications system and joint theater command communications.
The AN/TSC-124 groups users into nets with common cryptographic keys and
addresses. It allows a telephone type “dial up” of another net member,
mainly in a data mode. The frequency range of this system is extremely
high frequency (EHF) (uplink) and SHF (downlink).
Transmission Techniques
a. To use TACSAT communications effectively, it is necessary to
be familiar with the terminology and techniques that are used. It is not
practical to have a separate satellite for each radio net or link. The
satellite system must make provisions to relay signals of many nets at
the same time. This is called multiple access. There are two basic types
of multiple access --frequency division multiple access (FDMA) and time
division multiple access (TDMA).
(1) FDMA is the first technique used for satellite multiple
access because it uses existing frequency division technology and
equipment. It is simple to implement, has proven performance and
reliability, and is easy to maintain. Using FDMA, each terminal
accessing the satellite transmits on a different frequency to the
satellite. The satellite receives and retransmits the signals over a
broad bandwidth encompassing the frequency range of the ground stations.
The satellite electronics package is usually referred to as a
transponder. The satellite translates the frequencies and retransmits
them with the same relative frequency relationship back to the ground
nets. This translation avoids interference between the satellite’s input
and output signals.
(a) Ground radios in an FDMA satellite net must transmit and
receive on separate frequencies. These frequencies are spaced equal to
the satellite frequency translation. This prevents direct radio contact
between radios operating in the same net. Although this method is simple
and reliable, it has drawbacks. Each single-channel net or one-way link
requires two radio frequencies. A duplex link through the satellite
requires four frequencies. Also, for direct linkage between two ground
stations, without going through the satellite, frequency switching of
the ground radio transmitter to the satellite transmit frequency is
necessary. This complicates operational control and introduces the
potential for interference due to operator error.
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(b) With many nets operating at the same time, signals can be
mixed due to different signal strengths arriving at the satellite. This
is called intermodulation. It generates signals which can cause
interference and noise. These mixing products also reduce the useable
power output of the satellite. Satellite transmit power output must be
divided among all the users in an FDMA system. Any power used in mixing
and on noise reduces the power available for communications. Also, any
unequal distribution of power among the users can impact on the
successful operation of the FDMA satellite. Careful frequency selection
and control of ground station transmit power is necessary to make an
FDMA system work properly. Usually a centralized ground monitor and
control point is essential. Despite these limitations, FDMA is an
effective tactical system because of its simplicity. It foregoes the
need for sophisticated timing necessary in TDMA systems.
(2) TDMA assigns a specific time interval for each ground
terminal or net to use the satellite. This eliminates the FDMA need for
frequency and power control of each ground station accessing the
satellite. TDMA removes the potential for intermodulation caused by nets
operating through the satellite at the same time. With each net having
its own time to use the satellite, each net can use the maximum ‘power
and bandwidth of the satellite. However, to make the system work, rapid
switching between nets is necessary to eliminate delays in net
communications. This reduces the transmission time available to each
net. It requires careful timing at each ground station.
(a) An alternative to accurate timing is slow switching among
many nets or stations. Slow switching causes a delay in communications
but is overcome by a priority break-in feature. For example, by giving
each ground station satellite access for 4.5 seconds once every 5
minutes, 50 stations could be accommodated. A 0.5 second time slot is
available each 5 seconds for emergency break messages. This technique is
most attractive with narrative record communications operating in a
store and forward mode. The break-in feature is also useful for some
special communications requirements.
(b) Regardless of the switching speed, digital transmission is
almost an absolute necessity. The switching of time slots is digital;
therefore, the communications must match. This means all signals
transmitted in the TDMA system must be digital for transmission. Analog
signals must be converted before transmission and reconverted after
reception. However, using digital transmission and reception makes TDMA
more attractive because of the compatibility with electronic switching
systems and cryptographic equipment. TDMA communications is in short
intermittent bursts; therefore, the ground stations must store or buffer
information allowing continuous input and output of traffic.
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b. With multiple access, the number of channels on a satellite
is limited. If each channel through the satellite is dedicated to a
specific net or user, the number of users can quickly exceed the
available channels. If a given channel is not being fully used by a net,
a valuable satellite channel is partially wasted. This is not efficient
and leads to delays and limited channel availability. FDMA and TDMA do
not allow for efficient use of the available satellite resources.
(1) Demand assigned multiple access (DAMA) is a technique which
matches user demands to available satellite time. Satellite channels are
grouped together as a bulk asset, and DAMA assigns users variable time
slots that match the users information transmission requirements. The
user notices no difference --to him it seems he has exclusive use of the
channel. The increase in nets or users available by using DAMA depends
on the type of users. DAMA is most effective where there are many users
operating at low to moderate duty cycles. This describes many tactical
nets; therefore, DAMA is particularly effective with TACSAT systems.
(2) DAMA efficiency also depends on how the system is formatted.
Formatting a DAMA system is how the access is controlled. The greatest
user increase is obtained through unlimited access. This format sets up
channel use on a first-come-first-serve basis. Other types of formats
are prioritized cueing access and minimum percentage access. The
prioritization technique is suitable for command type nets, while the
minimum percentage is suitable for support/logistic nets. Regardless of
format, DAMA generally increases satellite capability by 4 to 20 times
over normal dedicated channel operation.
c. Spread spectrum multiple access (SSMA) is a technique which
uses a wideband signal to convey intelligence through the satellite.
This signal may be many hundreds of megahertz wide. The advantage of a
signal spread over a great bandwidth is that power density (watts per
hertz) is lowered by the same amount that the spectrum is widened. This
interchange of power for spectrum space can reach a point where signals
can be transmitted and received while hidden below the background noise.
Such low density signals can reduce the problem of interception and at
the same time prevent interference to other satellite users. Spread
spectrum systems allow many users to share a single wideband channel.
Information to be transmitted by spread spectrum is first converted into
digital form to provide a primary modulation of the carrier. A secondary
pseudorandom noise modulation of much wider bandwidth is then applied to
the carrier to spread the spectrum of the primary modulation. At the
receiving end, an identical noise generator, synchronized to the
transmitter, generates the same noise code to cancel it from the
incoming signal. Thus, only the transmitted information remains. This
spread spectrum technique is called direct sequence (DS). The basic form
of DS is produced by a simple, phase shift keying (PSK) carrier
frequency. In the DS spread spectrum signal, the modulated signal
appears instantly across the total bandwidth.
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(1) The advantages of DS spread spectrum processing are-Signals are difficult to detect.
Maximum transmitted power for the bandwidth used.
Interference and jamming protection.
Reduced noise.
Discrete address.
Multiple access.
(2) Another form of spread spectrum is frequency hopping (FH). FH
uses a pseudorandom code generator to switch the carrier frequencies
producing a hopping DS spread spectrum. Frequency hoppers can use
hundreds to thousands of frequencies.
d. In spread spectrum systems and TDMA, timing is a necessary
process. Transmitter-to-receiver phase and frequency timing requires
resolution before a spread spectrum or TDMA receiver can operate. These
problems are overcome by transmitting timing signals at the start of
each transmission. A system clock produces a timing preamble code for
timing of the network. The preamble of a transmission from any terminal
carries timing information for the receiving terminal. System or network
control assigns the terminal transmitted time slot. This carries timing
in the preamble and discrete address(es) in the data segment. Each
receiver uses the transmitted preamble for fine adjustments.
e. Addressing a message designated for a specific terminal is
similar to a telephone call. When dialing a telephone number, the
electronic switching equipment directs the telephone system circuits to
connect the caller and addressee. Basically, the telephone system has a
“discrete call” capability. A discrete call capability is required in
multiple access transmission systems. The form of discrete call needed
in a TDMA communications system is transmitter to receiver recognition,
not subscriber to subscriber. Although all receivers will fine-tune to
the timing signal, only the receiver recognizing its address in the code
will copy the text.
Planning and Control
a. Tactical communications networks change constantly. Unless
control of the network is exercised, communications delay and a poor
grade of service will result. The best method of providing this control
without hampering operation is through centralized planning. Execution
of these plans should be decentralized. This concept is applied to the
space systems portion and to the ground stations. The US military
satellite systems consist of terminals (ground segment), satellites
(space segment), and tracking, telemetry, and control (TT&C) terminals
(control segment).
b. The planning and system control process helps communications
systems managers react appropriately to the mission of the force
supported, the needs of the commander, and the current tactical
situation. The type, size, and complexity of the system being operated
establishes the method of control.
(1) Communications control is a process in which the matching of
resources with requirements takes place. This process occurs at all
levels of the control and management structure. In each case, the
availability of resources is considered.
(2) Operating systems control is the detailed hourly management
of a portion of a theater Army, Army group, corps, or division
communications system. Planning and control is according to the system
being used.
c. The Defense Communications Agency (DCA) provides technical
guidance on satellite control in support of the Joint Chiefs of Staff
(JCS). Course allocation of satellite payload communications resources
is done by DCA based on JCS directives. The Army, Air Force, and Navy
have operational responsibilities for satellites and satellite payloads.
These responsibilities involve using several sites worldwide to provide
planning and control for a communications satellite constellation.
d. Satellite control is split into two categories: TT&C and
payload control. Because there may be hundreds of users on a
communications satellite, payload control is often subdivided among
major user groups. In DSCS, a portion of the payload bandwidth and power
is used to support the GMF terminals. GMF managers and controllers
handle the planning and control. The overall DSCS controller monitors
the GMF portion of the satellite system either as a subnet or as
individual carriers. However, this monitoring depends on the
availability of satellite resources. Chapters describing the specific
system cover the user’s interface with satellite planning and control.
Space Segment Descriptions
a. The satellite system operating in the UHF band is the Fleet
Satellite (FLTSAT) System. FLTSAT is presently providing worldwide
support to all services and agencies between the latitudes of 70 degrees
north and 70 degrees south. However, the Navy primarily uses this
system. Each FLTSAT can relay communications on 23 separate radio
frequency (RF) channels. There is one fleet broadcast 25 kHz channel and
SHF beacon; nine fleet-relay, 25 kHz channels; 12 Air Force satellite
communications (AFSATCOM) narrowband 5 kHz channels; and one AFSATCOM
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wideband 500 kHz channel. FDMA allows access to the 500 kHz transponder
by seven high data rate (2.4 kbps) users and 13 low data rate (75 bps)
users. Army users may request using the nine fleet-relay channels, the
five nonprocessed 5 kHz channels, and limited access to the wideband
transponder. However, there are currently no satellite transponders
dedicated to Army use. Army users must send an access request directly
to the Air Force or Navy. Access is based on the established
prioritization schedule published in JCS MOP 178. The Office of JCS has
formed the Joint Communications Satellite Center (JCSC) to act as the
controlling agency for satellite access. Network control and spectrum
availability are the responsibility of the Air Force and Navy. All
non-Navy users must direct their frequency requests through their local
frequency management office to the Navy’s frequency management office.
The overall FLTSAT system has more than 600 user terminals on board
ships, aircraft, and on shore. The FLTSAT space segment consists of four
satellites in synchronous orbit. The satellite transponders operate in
US military UHF bands.
b. The multichannel TACSAT terminals use the spacecraft
transponders of the DSCS. The terminals use both DSCS II and DSCS III
satellites. The DSCS II satellite has two transponders, each providing
two operational channels. These transponders are cross-linked to provide
four operational channels to the earth coverage (EC) and narrow coverage
(NC) antennas. Each NC antenna can transmit and receive simultaneously.
(DCAC 800-70-1 covers on-board antenna interconnectivity of the DSCS II
channel.) The signal transmitted by the ground terminal is received at
the satellite in the 7.9 to 8.4 GHz frequency range where it is down
converted, amplified, and retransmitted in the 7.25 to 7.75 GHz
frequency range. The two NC antennas can be independently steered ±10
degrees, and the footprint --the part of the earth covered by the
antenna-- covers an area about 1,200 kilometers (750 miles) in diameter.
The newer DSCS II satellites have one of the NC antennas adjusted to
provide a 2,400 kilometer-wide (1,500 mile-wide) coverage area, known as
area coverage (AC). The EC antennas (transmit and receive horns) provide
coverage to about one-third of the earth’s surface.
c. The DSCS III satellite has six independent transponders (one
per channel), three uplink antennas to receive signals from earth
terminals, and five downlink antennas which retransmit the signals back
to earth. The signal transmitted by the ground terminal is received at
the satellite in the 7.9 to 8.4 GHz frequency range where it is
amplified, down converted, and retransmitted in the 7.25 to 7.75 GHz
frequency range. The DSCS III will replace the DSCS II satellites over a
period of time. At this time, both are in orbit. The DSCS IIIs have some
improvements over the DSCS IIs such as increased hardening, a nulling
capability (antijam function), and more transponders. However, the DSCS
III only has one NC gimballed dish antenna (GDA). This limits the number
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of locations that can be covered at any one time. The DCA can change
footprint locations. (DCAC 800-70-1 covers on-board antenna
interconnectivity of the DSCS III satellite channel.)
Electronic Warfare
TACSAT communications is an important element of the battlefield
command and control system. Part of the enemy’s resources are directed
against the satellite system through electronic warfare (EW). How
vulnerable we are to enemy EW and the success of our actions to deny the
enemy success in his EW effort depends on our equipment and our signal
personnel. While there are many components of EW, this manual deals only
with TACSAT communications systems. The first two EW components,
electronic warfare support measures (ESM) and electronic countermeasures
(ECM), are technical. We rely on military intelligence (MI) units and
the United States Army Intelligence and Security Command (INSCOM) for
advice and implementation of ESM and ECM. Radio electronic combat (REC)
is the enemy equivalent to our ESM and ECM. To counter enemy use of REC,
the Army relies on communicators to use electronic countercountermeasures (ECCM).
a. Electronic threat. The enemy uses REC measures to collect
intelligence data about our signal systems. The enemy then decides what
REC would be appropriate from the data gained through intercept. TACSAT
communications will be high on the enemy REC target list. Shortly after
tactical communications is placed in operation, the enemy will compile
data on the satellite. This data will most likely include-Data indicating the satellite’s orbit and location.
Information on frequency, bandwidth, and modulation used in
the satellite.
The amount, type, and frequency of traffic relayed by the
With the satellite relay located, the primary enemy REC threat then is
directed toward locating ground stations through radio direction finding
(RDF). Due to the highly directional antennas used with SHF/EHF TACSAT
communications radios, there is a low probability of intercept and
direction finding. But, a satellite-based intercept station orbiting
near our satellites can be successful. In this case, the analysis effort
can be done by the enemy on his home ground, far from the battlefield.
Because of the enemy’s massive computer support TACSAT communications
stations will hide very little from the enemy. Even without ground
station locations, jamming can be directed towards the satellites. When
this is done, TACSAT communications nets working through the satellite
are operating in a “stressed” mode. Jamming signals directed toward the
satellite can originate far from the battlefield. Because of the
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directional antennas and frequencies used, jamming directed toward
ground stations must come from nearby. Besides jamming, the enemy may
attempt deception from either the ground or his own satellites. The
enemy may attempt to insert false or misleading information and may also
establish dummy nets operating through our satellites to cause confusion.
In low- and mid-intensity conflicts however, there is a reduced
electronic threat.
b. Defensive EW. TACSAT communications must operate within the
REC environment just described. To do this, it is necessary to use
available antijamming equipment and sound countermeasures.
Communications discipline, security, and training underlie ECCM.
Communications security (COMSEC) techniques give the commander confidence
in the security of his communications. ECCM equipment and techniques
provide confidence in the continued operation of TACSAT communications
in a hostile EW or stressed environment. Particularly in TACSAT
communications, the two are closely related techniques serving an ECCM
(1) COMSEC techniques protect the transmitted information.
Physical security safeguards COMSEC materiel and information from access
or observation by unauthorized personnel using physical means.
Transmission security (TRANSEC) protects transmissions from hostile
interception and exploitation. COMSEC and TRANSEC equipment protects
most circuits. However, some TACSAT orderwires may not be secure.
Technical discussions between operators can contain information important
to the enemy. The nature of any mission gives the enemy access to
critical information about commanders, organizations, and locations of
headquarters. Although revealed casually on the job, this information is
sensitive and must be protected. FM 34-62 covers signals security
(SIGSEC) and information on COMSEC measures and techniques. TC 24-4A
covers COMSEC applications for TACSAT operations.
(2) ECCM techniques protect against enemy attempts to detect,
deceive, or destroy friendly communications. Changing frequency can
defeat jamming. This requires the jammer to determine the new frequency
and move to it. Meanwhile, the frequency can again be changed. This is
the principle behind FH. Since it takes about 0.25 seconds for the earth
station satellite-earth station trip, FH 4 times per second denies the
jammer access to the satellite to earth link. FH at this rate must rely
on automated equipment. FH at rates between 4 per second and 75 per
second effectively avoids intercept and jamming when the enemy can
receive only the downlink. With these low rates, bandwidth is still
minimum while providing secure communications. FH forces the jammer to
spread his energy (broadband jamming). This reduces the jammer noise
density on any one channel. Wideband spread-spectrum modulation is
another effective antijamming technique. With this technique, the
information transmitted is added to a pseudorandom noise code and is
used to modulate the TACSAT terminal transmitter. At the receiving end,
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an identical noise generator synchronized to the transmitter is used. It
generates the same noise code as the one at the transmitter to cancel
the noise signal from the incoming signal. Thus, only the transmitted
information remains. The spread spectrum signal can occupy the entire
bandwidth of the satellite at the same time with several other spread
spectrum signals. Each signal must have a different pseudorandom noise
code. The noise code looks the same to the jammer whether or not it is
carrying intelligence. This forces the jammer to spread his energy
throughout the entire bandwidth of the random noise. This results in a
reduced jamming noise density. The jammer has no knowledge of whether
the jamming is effective.
c. Electromagnetic compatibility. Electromagnetic compatibility
occurs when all equipment (radios, radars, generators) and vehicles
(ignition systems) operate without interference from each other. With
TACSAT communications terminals, a source of interference is the sun, a
very strong source of broadband noise. However, factors such as location
and antenna orientation can be controlled to eliminate this source of
noise. For each equipment, use proper grounding techniques and follow
safety considerations. When TACSAT communications terminals and other
sets must be collocated, use a plan that prevents antennas from shooting
directly into one another. Maintaining an adequate distance between
antennas reduces mutual interference. Desensitization is the most common
interference problem. This reduces receiver sensitivity caused by
signals from nearby transmitters. Electromagnetic compatibility must be
included in the plans for siting a TACSAT communications station.
d. Electromagnetic pulse (EMP). EMP is a threat to all
sophisticated electronic systems. Under the proper circumstances, a
major portion of the energy released during a nuclear detonation appears
as an EMP. It has the same frequencies or wavelengths as those used by
some of our TACSAT communications radios.
(1) EMP has two unique properties. First, EMP has a great “killing
range.” EMP can disable electronic systems as far as 6,000 kilometers
(3,720 miles) from the site of the detonation. Second, EMP can cause
severe disruption and sometimes damage when other weapon effects are
absent. A high-yield nuclear weapon, burst above the atmosphere, could
be used to knock out a TACSAT communications system’s operational status
without doing any other significant damage. The range of EMP is
diminished if the weapon is detonated at a lower altitude within the
atmosphere. An idea of the amplitude of EMP can be gained when we
compare it with fields from man-made sources. A typical high level EMP
could have an intensity which is 1,000 times more intense than a radar
beam. A radar beam has sufficient power to cause biological damage such
as blindness or sterilization. The EMP spectrum is broad and extends
from low frequencies into the UHF band. The most likely EMP effect would
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be stopping communications service temporarily. This can occur even
without permanent damage. This delay could give an enemy enough of an
advantage to change the outcome of the battle.
(2) The issue is protection against EMP. All TACSAT
communications systems incorporate built-in features and techniques to
counter the EMP effects. Shielding can further reduce the level of the
EMP. Shielding is using equipment location and possible known directions
of nuclear blasts to reduce EMP exposure. Shielding also depends on good
grounding. Electronic systems depend on protection against EMP.
FM 24-11
Chapter 2
Manpack Single-Channel System
System Description
a. Manpack single-channel TACSAT terminals provide reliable,
highly portable communications. They have minimum setup and teardown
time and satisfy a need for extended distance communications.
b. The manpack system operates in the UHF band between 225 MHz
and 400 MHz. The manpack terminals use a UHF satellite system (FLTSAT
and Air Force satellite (AFSAT) space segments).
c. The Army terminals using the FLTSAT space system are the
ANIPSC-3, AN/VSC-7, AN/URC-101, and AN/URC-110. The AN/PSC-3 is a
manpack terminal carried by one operator. The AN/VSC-7 is a vehiclemounted terminal which normally acts as a net control station (NCS) and
can control up to 15 subscribers. The AN/URC-101 and AN/URC-110 are
manpack terminals each carried by one operator.
a. Army units such as Special Forces groups and Ranger battalions
deploy manpack TACSAT terminals worldwide. The physical environment does
not restrict these deployments. The terminals are lightweight and
compact, and they can be moved easily by one person. The NCSS are
normally vehicle-mounted. They are usually operated from a forward
operating base by Special Forces groups or from a battalion headquarters
by Ranger battalions. A network can be a small deployment (three to four
terminals with one AN/VSC-7/NCS) or a larger deployment (more than one
b. Manpack terminals deployed worldwide are issued to support
Army units. AN/VSC-7s and AN/PSC-3s satisfy the real-time mission
requirements of the following organizations:
Special Forces.
Ranger battalions.
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Airborne/air assault divisions.
Selected infantry divisions (light and mechanized).
a. The Special Forces units use the AN/PSC-3s for group/
detachment headquarters, forward operating bases, and operational teams
spread over extended distances. Command and control between major
headquarters is primarily secure voice. All users at the Special Forces
team level operate in a data burst mode using the OA-8990 data burst
b. The Ranger regiment/battalions command nets provide command
and control from regimental headquarters through company headquarters.
They use secure voice and data burst in their operations.
c. The airborne/air assault divisions use the AN/PSC-3s primarily
to provide a long-haul command and control link between major
headquarters during initial deployment. Once on the ground, those
headquarters still requiring a communications link not available by LOS
means or by multichannel satellite link will continue to operate via the
AN/PSC-3 network. The primary mode is secure voice, though secure
teletype (AN/UGC-74) is also used.
d. Selected infantry divisions (light and mechanized) use the
A.N/PSC-3s to provide a long-haul command and control link between major
headquarters during initial deployment of a contingency operation. The
primary mode is secure voice, though secure teletype (AN/UGC-74) is also
System Configuration
a. The AN/PSC-3 is a battery operated, highly portable, manpack
TACSAT terminal. It employs an RT-1402 receiver/transmitter (R/T) unit
that provides two-way communications in the frequency range of 225 MHz
to 400 MHz. The R/T functions in both satellite mode and LOS mode of
operation. It can be configured to provide data or secure voice.
(1) In the data mode, it uses the digital message device group
(DMDG) OA-8990 as the input/output (I/O) device. It provides data rates
of 300 bps or 1,200 bps.
(2) In the secure voice mode, the AN/PSC-3 uses either the
advanced narrowband digital voice terminal (ANDVT) or a COMSEC interface
device such as the VINSON KY-57.
FM 24-11
(3) In addition to voice and data, the AN/PSC-3 can interface
with facsimile, teletype, net radio interface (NRI), and FM
retransmission media.
b. The NCS uses the same basic AN/PSC-3 R/T unit reconfigured to
form an AN/VSC-7. The vehicle’s electrical system provides power for
operation. The NCS can control as many as 15 terminals in a network.
Because it is a single-channel system, it is configured with data needs
being satisfied by some terminals and secure voice needs being satisfied
by other terminals. The call mode operation is a unique calling function.
It allows the sending station to alert a distant unit with a visual
indication. It also allows an optional 5-second audible alarm. The NCS
can transmit or receive any one of 15 selective calls. It can also
receive all conference calls regardless of the selective control setting
on the NCS applique front panel. The NCS selects any one of the 15 units
operating in its net for selective call transmissions. Conference calls
will be received by all units operating in the net with their controls
set to receive selective call messages.
Antijamming and ECCM Techniques
Physical damage and hostile electromagnetic jamming threaten all
communications including satellite. This system presently does not offer
any antijamming protection to the TACSAT terminal. Mobile TACSAT
terminals offset the need for providing protected multiple ground relay
sites. In addition, it reduces exposure time to hostile actions. The
protection of these terminals by terrain, such as valleys, further
reduces the possibility of detection. Where ordinary means of
communications are subject to varying degrees of RDF, the satellite
system can be used to deter enemy RDF success. The short transmission
times of burst mode present less attractive jamming targets than the
longer continuous communications of regular nets. The only options
available to tactical UHF satellite terminals are data burst, alternate
frequency selection, mobility, and reducing the on-air time of each
FM 24-11
Chapter 3
Special Communications System
System Description
a. The SCS permits direct, automated, real-time communications
in support of joint forces requiring rapid deployment or redeployment.
SCS terminals send and receive record narrative messages over a 5 kHz,
narrowband satellite channel.
b. The SCS operates in the UHF spectrum using the 225 to 400 MHz
band. The Army, Navy, and Air Force operate SCS terminals. They consist
of satellite communication terminals AN/GSC-40, AN/GSC-40A(V)l,
AN/GSC-40A(V)2, and AN/MSC-64(V)2.
c. The SCS terminal, AN/MSC-64(V)2, is a highly mobile set
installed in an S-280 type shelter. The rack-mounted combined ground
command post terminal (CGCPT) AN/GSC-40(*)(V)(*) is configured to the
needs of the fixed site at which it is installed.
a. SCS terminals are deployed in Europe and Korea. All Army
terminals function within a TACSAT network made up of force terminals
(FTs) and command post (CP) equipment.
b. All SCS terminals deployed in a theater are operated as a
network. The US Pacific Air Force has operational responsibility for all
Air Force SCS terminals in the Korean theater. The US Army provides
off-site maintenance support for US Air Force terminals in the Korean
theater. Within joint commands, the US Army component commands are
responsible for operation and maintenance of the SCS terminals assigned
to their subordinate units.
c. SCS terminals deployed to Europe and Korea support Army,
Navy, and Air Force real-time communication requirements for on-going
special missions.
FM 24-11
a. The SCS terminal is a single-channel TACSAT set. Each SCS
terminal uses an I/O device. The device has a keyboard and display for
editing and composing narrative traffic. The keyboard and display
equipment is the I/O unit MX-10159/G that functions as the sole
subscriber data terminal equipment (DTE) . The AN/MSC-64(V) and
AN/GSC-40(V) are self-contained terminals.
(1) The AN/MSC-64(V)2 contains a complete communications system
housed in an S-280 shelter, carried by a 2 l/2-ton truck, and powered by
a trailer-mounted, 10-kilowatt generator. The AN/MSC-64(V)2 can also be
powered by the vehicle engine with a 100 amp kit. The I/O unit organic
to the terminal is the primary DTE and can be remoted up to 1,500 feet
(455 meters). A low gain antenna is used during mobile operations. A
high gain antenna is used during stationary operations.
(2) The AN/GSC-40, AN/GSC-40A(V)l, and AN/GSC-40(V)2 are rack
mounted CGCPTS. These terminals are installed in CPS and configured
according to the physical limits of the site.
b. A high degree of network flexibility is accomplished by using
a TDMA control structure and a CGCPT. This technique allows
communications to be executed on a time-shared basis between other
terminals within the theater network. The terminal can operate in the
random or time division multiplexing (TDM) modes. The random mode of
operation allows the user to enter the TACSAT communications network on
a random basis using an open selected channel.
Control and Management
a . The control and management procedures discussed here pertain
to the communications between AN/GSC-40(V) and AN/MSC-64(V). The
AN/GSC-40(V) performs the network control function (NCF) for a net of
AN/MSC-64(V) FTs.
b. The NCF, normally located within a CP, performs the following
subnet control actions:
Transmits network timing synchronization message for
initialization of a terminal entering the network and for retiming all
receivers within the network.
Transmits satellite operating mode for use by FTs.
Transmits crypto-control data.
FM 24-11
Performs message preemption to allow transmission of a
message with a higher precedence.
In stressed mode, identifies each frame, establishes
priorities, and dynamically assigns use of next slot.
The FTs perform the following control actions:
Acknowledges/transmits messages.
Loads and monitors the synchronization code.
Selects transmit channel and time slot.
Monitors emergency action message alarm.
d. The AN/MSC-64(V) FT is transported by a 2 l/2-ton truck and
trailer, and is crewed by three operators. Other technical data is
listed below:
Frequency range--225 to 400 MHz.
Power output-- 10 to 100 watts.
Operating mode--AFSAT.
Modulation type --Noncoherent frequency shift keying (FSK).
Data rate--75 bps.
Encryption device--TSEC/KN-2.
Spread spectrum technique--FH.
Antijamming and ECCM Techniques
a. The SCS uses FH emission techniques as an ECCM capability and
terminal hardening against the effects of EMP. The CGCPT uses wideband
operation of coded m-ary FSK, pseudorandomly generated, suppressed
carrier RF burst that is frequency hopped. This type of RF emission
provides excellent ECCM protection for discrete addressing, message
privacy, and multiple addressing. For narrowband operation, noncoherent
FSK is used.
b. Wideband operation is only used between the CGCPT and the
National Command Authority AFSATCOM terminals. SCS, a UHF system, lacks
any antijamming protection to the TACSAT terminal outside of the emission
techniques listed previously. The short transmission times of burst
communications present less attractive jamming targets than do longer
FM 24-11
continuous communications of regular nets. The only options available to
TACSAT UHF terminals, in addition to short burst communications, are
alternate frequency selection and mobility.
FM 24-11
Chapter 4
Multichannel SHF System
System Description
a. Multichannel TACSAT terminals provide a reliable
communications system. These terminals provide range extension for the
area communications system.
b. The multichannel TACSAT systems use the DSCS II or DSCS III
satellite and operate in the 7.25 to 8.4 GHz frequency range. The Army,
Air Force, and Marine Corps operate these terminals. The Army and Marine
Corps use the AN/TSC-85( )/93( ) while the Air Force uses the AN/TSC 94A/
l00A. These terminals are compatible with Tri-Service Tactical
Communications (TRI-TAC) and Mobile Subscriber Equipment (MSE) systems.
These multichannel TACSAT terminals use FDMA. Therefore, centralized
frequency selection and uplink power control are required.
a. Theater through brigade level commanders, special
contingencies, and selected divisions use tactical multichannel satellite
systems to support Army mission requirements. These systems were
developed to augment existing terrestrial multichannel communications
b. Multichannel satellite systems are designed primarily for
trunking. Consider these factors when selecting a link requirement for
multichannel TACSAT terminals:
Criticality of the link to tactical command and control and
the availability of other primary or supporting transmissions means.
Ground range over which the link must be operated in various
Responsiveness and flexibility required with respect to
siting and system reconfiguration.
Link survivability requirements.
FM 24-11
Consider these factors when deploying the AN/TSC-85( )/93( )s:
Equipment capabilities.
Network configuration.
System descriptions.
d. The AN/TSC-85( ) TACSAT terminal is housed in a modified
S-280 shelter. It operates with an organic AS-3036/TSC (8-foot diameter)
antenna which is moved in an antenna pallet transit frame (APTF). It may
also operate with either the nonorganic AS-3199/TSC (20-foot diameter)
antenna or the OE-361(V)/G quick reaction satellite antenna (QRSA). All
three antennas operate with DSCS satellites.
(1) The four curbside racks inside the shelter contain the
baseband (multiplexing or demultiplexing) equipment. The four racks on
the roadside of the shelter contain the modems and intermediate frequency
(IF) or RF assemblies. The electronic equipment can operate in a nuclear,
biological, chemical (NBC) environment.
(2) Each part of the satellite terminal equipment (shelter and
APTF) is transportable by road, air (C-130, C-141, C-5A, or helicopter),
rail (flatbed), and sea (ship). For the shelter to be mobile by rail or
air, the M-720 mobilizer (nonorganic) must be used.
(3) Terminal setup time for a team using the organic AS-3036/TSC
is 30 minutes (three-person crew).
e. The AN/TSC-85( ) TACSAT terminal (nodal terminal) provides
the following:
Transmission of a single SHF uplink carrier with up to 48
channels of voice and/or digital data (internally multiplexed). An
additional 48 channels of voice and/or digital data from a remote
(externally) multiplexed source may also be transmitted.
On the downlink side, four carriers can be received,
demodulated, and switched to user interfaces.
Fully independent operation from a 15-kilowatt, three-phase,
five-wire diesel generator or compatible commercial power.
Link with a nodal or non-nodal terminal in the point-to-point,
hub-spoke, and mesh or hybrid mode. (See Figures 4-1 through 4-3.)
Links with DSCS gateway terminal to provide Defense
Communications System (DCS) entry.
FM 24-11
f . A modified S-250 shelter houses the AN/TSC-93( ) TACSAT
terminal. It operates with the AS-3036/TSC (8-foot diameter) antenna.
(1) The shelter is normally transported on the bed of a 2 1/2-ton
truck with the disassembled 8-foot antenna on an M1028 commercial
utility cargo vehicle (CUCV). Each truck tows a trailer-mounted diesel
generator or power unit.
(2) Three curbside racks inside the shelter contain the baseband
(multiplexing or demultiplexing) equipment. Three racks on the roadside
of the shelter contain the modem and IF or RF assemblies.
(3) Each part of the satellite terminal equipment is transportable
by road, air (C-130, C-141, C-5A, or helicopter), rail (flatbed), and
sea (ship).
g. The AN/TSC-93( ) TACSAT terminal (non-nodal terminal) provides
the following:
Transmission of an SHF uplink carrier with up to 24 channels
of voice and/or digital data (internally multiplexed).
Link with a non-nodal terminal in the point-to-point or a
nodal terminal hub-spoke mode.
On the downlink side, can receive, demodulate, and switch a
single SHF carrier via the demultiplexing equipment to the user interface.
Fully independent operation from a 10-kilowatt, three-phase,
five-wire diesel generator or compatible commercial power.
Link with DSCS gateway terminal to provide DCS entry.
a. Limitations. Channel capacity on DSCS II and DSCS III
satellites limits the number of TACSAT terminals that can operate at any
one time. This number varies depending on several factors. Thes e
factors can include the type of terminal, number of channels, condition
of terminals and satellite, size of antenna, and location of terminals
within satellite footprint. These factors and others (for example,
weather) affect how many terminals can use a satellite. For these
reasons it is not possible to give a clear-cut number of terminals that
can be operated at any one time. Unfortunately, there is not enough
space segment to satisfy all the users. It should be stressed that DSCS
II and DSCS III satellites support Army, Navy, Air Force, Marine, and
other DOD/non-DOD users. The satellite channels on DSCS II and DSCS III
are JCS assets and therefore not dedicated to any particular service.
FM 24-11
(1) The divisions receiving multichannel TACSAT terminals are
selected based on their operational areas, terrain, and distance
considerations. The signal battalion installs, operates, and maintains
the AN/TSC-85( )/93( )s.
(2) In selected divisions, five multichannel TACSAT terminals
provide extended distance connectivity. Division main and division
support command (DISCOM) use one AN/TSC-85( ) each. One AN/TSC-93( ) is
deployed to each of the three maneuver brigades. This is at the
commander’s discretion. An AN/TSC-85( ) at division main might terminate
links from each maneuver brigade and DISCOM. During division main
displacements, the terminal at DISCOM acts as the hub.
c. Corps. In the corps, two AN/TSC-85( )s and four AN/TSC-93( )S
are pooled to provide support based on the general support (GS) concept.
Terminals in support of corps are used for various missions such as
restoration of critical links, out of sector operations, and deep
operations. This concept has been developed based on the range extension
capability of the MSE system. The corps signal brigade installs,
operates, and maintains the AN/TSC-85( )/93( )s.
Contingency corps.
(I) AN/TSC-85( )/93( )s are distributed to the contingency corps
based on their mission. The corps signal brigade installs, operates, and
maintains the AN/TSC-85( )/93( )s.
(2) In the contingency corps, five AN/TSC-85( )S and eight
AN/TSC-93( )S provide a low capacity multichannel (6/12 channels) range
extension capability, independent of terrain and siting restrictions. It
provides links from corps main and forward CPs to corps support command
(COSCOM), the subordinate divisions, and other attached units.
Echelons above corps (EAC).
(1) At EAC, multichannel TACSAT provides connectivity between key
EAC headquarters. EAC has been provided six AN/TSC-85( )s and ten
AN/TSC-93( )s based on distance, terrain, criticality of links, and the
need to augment LOS relays.
(2) TACSAT provides connectivity between major Army and combined
commands in Europe and Korea.
Contingency support.
(1) For Army and JCS crisis contingency support missions,
AN/TSC-85( )/93( )s are allocated to a TACSAT company, table(s) of
FM 24-11
organization and equipment (TOE) 11603. They deploy in support of Army
and JCS contingency missions worldwide. This unit uses M-720 mobilizers
for its AN/TSC-85( )s. The USAISC installs, operates, and maintains the
AN/TSC-85( )/93( )s.
(2) The contingency corps area of operations is normally much
larger than a doctrinal corps and requires augmentation. Three
AN/TSC-85( )s and six AN/TSC-93( )s are allocated to the 235th Signal
Detachment. They augment the contingency corps and Army contingency
missions. This unit is also authorized M-720 mobilizers for its
AN/TSC-85( )s.
Control and Management
a. USARSPACE RSSC GMF managers control and manage the TACSAT
communications SHF multichannel terminals. These managers are collocated
with the DCA elements at DCA-Europe, DCA-Pacific, and DCA-Washington.
The GMF managers are the theater Commander in Chief’s (CINC) resource
managers and interface to the DSCS and DCA. DCA is the overall DSCS
system manager and technical director providing satellite resources to
the GMF managers.
b. Communications control matches resources against requirements.
It occurs at all levels of the control and management structure. The
TACSAT multichannel terminals use the DSCS space system which includes
the DSCS II and DSCS III satellites. The availability of resources is
considered in all cases as in the single-channel TACSAT program. Emphasis
is also placed on mission and organizational priorities in accordance
with JCS MOP 178.
c. The process for GMF satellite control, management, and access
flow follows the path outlined below.
(1) Communications system planning element (CSPE). The CINC’S
CSPE planner coordinates, consolidates, and prioritizes the user elements
satellite requirements within his theater. He submits satellite access
requests (SARS) to the GMF managers. On approval he receives the
satellite access authorization (SAA) that provides operation orders
(OPORDS) or operation plans (OPLANS) to the terminal operators.
(2) RSSC GMF manager. The RSSC GMF manager-Receives the SAR from the CSPE.
Coordinates with DCA for added resources.
FM 24-11
Develops alternate plans and coordinates with the CSPE if
SARS cannot be met due to resource restrictions.
Initiates and transmits an SAA to the CSPE or denies access
based on available resources.
(3) DCA. The DCA-Is the system manager and technical director for the DSCS.
Allocates the resources available.
Adjudicates resource requirements between GMF and DSCS users.
(4) JCS. The JCS adjudicates differing resource requirements of
the CINC which cannot be resolved between the CSPE, the GMT manager, and
the DCA due to resource limitations.
(5) GMF network controller (GNC). The GNC-Is under the operational control (OPCON) of the GMF manager.
Has OPCON of all GMF TACSAT terminals.
Uses resources within the GMF allocation and the SAA.
(6) The Defense Satellite Communications System Operations Center
(DSCSOC) controller. The DSCSOC controller-Is the satellite network controller (SNC).
Has overall control of the DSCS satellite.
Monitors the GMF subnetwork for violations and notifies the
GNC for correction.
System Configuration
a. Capabilities. The AN/TSC-85( )/93( ) terminal configurations
allow digital interface with TRI-TAC equipment and MSE. They also
provide limited capability for analog input and an ECCM capability for
operation in a stressed environment. The Product Improvement Program
incorporates replacing the TD-660s, TD-1065s, TD-1069s, KG-27s, and
adding the antijam/control modem (AJ/CM), low rate multiplexer (LRM)/
TD-1389, and KG-94A. Upon completing the program, the modified terminals
will be redesignated as AN/TSC-85B/93B.
FM 24-11
b. AN/TSC-85( ). Four TD-660s and TD-1065s will be replaced by
four TD-1389s to function as the multichannel multiplexer for unstressed/
clear mode communications. Two CV-1548 telephone signal converters and
two MX-9635 echo suppressors will be removed and two CV-1548S and
MX-9635S will remain. These two unit pairs will remain to support use of
two-wire telephones. Four TD-1069s, or their reserved cavity locations,
will be removed and replaced by four TD-1389s to function primarily as a
multiplexer for the AJ/CM, or alternately as a submultiplexer into
another TD-1389. Eight TD-1389s will be installed in each AN/TSC-85( ).
Sufficient crosshatch capability will be provided to permit any TD-1389
to function in any role. Baseband patching will be available to provide
access to all baseband ports on the shelter entry panels. This will
allow the individual channels of the CV-1548/MK-9635 to be patched into
any user channel as required. In addition, four KG-27s will be replaced
by four KG-94As to provide bulk encryption for four unstressed/clear
mode multichannel groups. A nodal terminal AJ/CM will be installed. It
will provide an antijamming communications channel and will replace the
FM control orderwire. Four STU-III/equivalent 2.4 kbps secure voice
devices will be added to provide an AJ/CM stress mode secure voice
capability. All other items in the terminal will remain the same.
c. AN/TSC-93( ). Two TD-660s and two TD-1065s will be replaced
by one TD-1389 to function as the multichannel multiplexer for unstressed/
clear mode traffic. One CV-1548 and one MX-9635 will be removed and one
of each will remain to support use of two-wire telephones. One TD-1069,
or its reserved location, will be removed and replaced with one TD-1389
to function primarily as a multiplexer for the AJ/CM or alternately as a
submultiplexer into another LRM/TD-1389. A total of two LRM/TD-1389s
will be installed. Sufficient crosshatch capabilities will be provided
to permit any TD-1389 to function in any role. Baseband patching will be
able to access all baseband ports on the shelter entry panels. This will
allow the individual channels of the CV-1548/MX-9635 to be patched into
any user channel as required. In addition, two KG-27s will be replaced
by one KG-94A to provide bulk encryption for one unstressed multichannel
group. A non-nodal terminal AJ/CM will be installed. This AJ/CM will
provide an antijamming communications channel and replace the FM control
orderwire. One STU-111/equivalent will be added to the AN/TSC-93( ) to
provide an AJ/CM stress mode secure voice capability.
d. Differences. The main differences in tactical multichannel
terminal configurations are the types and amount of redundant equipment
in the configuration and the terminal’s communications capability. The
equipment is configured in either a nodal (hub) or non-nodal (spoke)
configuration. A nodal terminal can be configured to operate with up to
four terminals in a multipoint operation. Any two terminals, either
nodal or non-nodal, can be configured to provide a point-to-point
FM 24-11
Antijamming and ECCM Techniques
a. AJ/CM is a family of spread-spectrum modem equipment designed
to provide GMF TACSAT terminals with an ECCM capability for operation in
a stressed environment. The normal mode of operation for high capacity
links in a benign or nonstressed environment uses the current biphase
shift keying/quadraphase shift keying (BPSK/QPSK) modems and FDMA link
The family of modems consists of a network control terminal
(NCT), a nodal terminal (NT), and a non-nodal terminal (NNT). The AJ/CM
provides a lower capacity 75 bps and 32 kbps communications capability
and an antijamming control orderwire.
(1) NCT modem. The AN/MSQ-114/FSQ-124 satellite control and
monitoring systems use the NCT modem. It is made up of two chassis
assemblies: the MD-1133 and the OX-63 coder group.
(a) The MD-1133 network control unit (NCU) interfaces with the
terminal frequency reference and distributes time and frequency to the
NCT internally. The NCU also provides the NCT modem modulation/
demodulation functions. User commands initialize and control NCU hardware
elements to perform major NCT operations or processing. The NCT contains
bus logic to control an externally-programmable down-converter. The NCT
also provides modem and network status monitoring and provides status
and messages to the NCT operator.
(b) The OX-63 coder group, TRANSEC, 4-channel unit houses four
KGV-9 TRANSEC modules, associated interface circuits, and the necessary
power supplies.
(2) NT modem. Army and Marine AN/TSC-85As and Air Force
AN/TSC-100As use the NT modem. It is made up of three chassis assemblies:
the MD-1131 modem, the MD-1132 communications unit, and the OX-64 coder
(a) The MD-1131 modem contains a beacon demodulator, a 75 bps
critical control circuit (CCC), and a variable data rate 75 bps to 32
kbps link communications circuit (LCC). This modem also contains all
operator controls.
(b) The MD-1132 communications unit contains three LCCS. These
circuits provide the three links required for hub operation.
(c) The OX-64 coder group, TRANSEC, 10-channel unit houses ten
KGV-9 TRANSEC modules, associated interface circuits, and the power
FM 24-11
(3) NNT modem. Army and Marine AN/TSC-93As, Air Force
AN/TSC-94As , and selected satellite fixed station gateway terminals use
the NNT modem. It is made up of two chassis assemblies: the MD-1131
modem and the OX-63 coder group.
(a) The MD-1131 modem is identical to the NT modem.
(b) The OX-63 coder group, TRANSEC, 4-channel unit is identical
to the NCT modem.
Data Entry
Data entry requirements for the operator of a multichannel
TACSAT terminal AN/TSC-85( )/93( ) consist of information (data)
extracted from the SAA by the CSPE and included in either the mission
OPLAN or the exercise OPORD. This information takes the form of-Operating frequencies. (May not apply until SAA is received.)
Data rates.
Transmit power. (May not apply until SAA is received.)
Mission configuration.
Terminal identification.
Terminal locations.
Satellite “look angles” (azimuth and elevation). (May not
apply until SAA is received.)
Mission start and stop time.
Priority of communications.
b. The CSPE extracts this information from the OPLAN/OPORD and
provides it to the terminal operator. The data entries are categorized
and differentiated between operating parameters , network characteristics,
and configuration routines. Figures 4-4 and 4-5 are examples of data
entry sheets.
(1) Operating parameters include-Transmit frequencies.
Receive frequencies.
Transmit power.
FM 24-11
Terminal locations.
Satellite “look angles” (azimuth and elevation).
(2) Network characteristics include-Data rates.
Network configurations.
Terminal call sign.
FM 24-11
FM 24-11
FM 24-11
Chapter 5
Multichannel Control System
System Description
a. With multichannel TACSAT communications terminals in use by
the Army, Air Force, and Marine Corps, the DSCS controller cannot
accommodate the increased number of users. The ground mobile forces
satellite communications (GMFSC) system operates as a subnetwork
providing its own control system. This prevents interference degradation
for other users of the DSCS SHF satellites.
b. The GMF satellite communications control centers (GMFSCCC),
AN/MSQ-114 and AN/FSQ-124, provide mobile and fixed control facilities.
The USAISC’S operation and control procedures contain specific
information and instructions on GMFSC planning control, management, and
terminal user procedures. (These procedures are currently being revised.)
c. Specially trained US Army GMF controllers provide GMFSC
control for the terminals deployed by the multiservice (Army, Air Force>
and Marine Corps) GMFSC system. The GMF controllers continuously monitor
the downlink signals for all terminals in their networks to control
uplink signals. They direct changes as necessary. The controller ensures
that all terminals operate within the proper limits of frequency, power,
and channel capacity. Should any discrepancies take place, the controller
communicates by orderwire to initiate the changes necessary.
d. The GMFSCCC operates in the SHE frequency range of 7.9 to 8.4
GHz transmit and 7.25 to 7.75 GHz receive. Orderwire and AJ/CM units are
used for communicating with terminals under their control. The satellite
automatic monitoring system (SAMS) is used to monitor downlink
frequencies of all terminals. This provides control over uplink power
and frequency.
The AN/MSQ-114 is usually deployed one unit per theater of
operation. Since the AN/MSQ-114 is a limited production item, its
deployment is rigidly controlled. The AN/MSQ-114 can support forward
deployed forces, nonforward deployed forces, or contingency operations.
Nonforward deployment usually refers to the home location of the GMFSSCCC
FM 24-11
(either AN/MSQ-114 or AN/FSQ-124). The control system must be within the
respective satellite footprint, which usually is the NC/AC antenna
footprints for DSCS II or the GDA footprint for the DSCS III satellites.
(See Figures 5-1 through 5-4.) Using DSCS II, a GMFSCCC located in Korea
can control GMF terminals in CONUS, provided the control system and GMF
terminals are within the NC/AC footprints on that satellite. (See Figure
5-3.) On DSCS III, the control system and GMF terminals must be within
the GDA footprint. If the NC/AC or GDA footprint is moved to support a
mission so that the control system falls outside the footprint, the
AN/MSQ-114 would be deployed into a footprint to allow control coverage
of the GMF mission.
a. In their normal employment, the AN/MSQ-114 and the AN/FSQ-124
can control a number of GMFSC terminals. The exact number of terminals
being controlled depends on the network configuration and the mission
requirement. A point-to-point configuration is used when connectivity
between two low capacity terminals is desired. The hub-spoke
configuration uses a multichannel terminal as the hub. Up to four low
capacity terminals are used as the spokes. When at least two hub
terminals are connected by communications and each operates with up to
three spoke terminals, a hybrid configuration is derived. The control
terminal can monitor and control any configuration that may be active
within the control area.
b. In the networks designated for control by an AN/MSQ-114
terminal, the controller-Coordinates satellite access data with the GMF manager.
Establishes positive GMFSC subnetwork satellite control.
Evaluates and determines satellite link parameters.
Establishes and reconfigures approved satellite networks.
Conducts antijamming operations.
The first step in the start procedure after the AN/MSQ-114 is on station
at a new location is to activate the control orderwire to the DSCS
controller. Frequencies to be transmitted and received are authorized by
the GMF manager from an allotment granted to the GMFSC system by DCA.
Other system parameters that are determined prior to start are transmit
power, number of channels, and type of modulation coding priority. The
GMF controller accesses each tactical terminal using the control terminal
(CT) orderwire. The controller then directs the adjusting of transmit
power to achieve planned link performance. Measurements are made and
entered into the SAMS for real-time monitoring of the link.
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c. To evaluate link parameters, the SAMS monitors the network
for out of tolerance conditions. Manual spectrum analyzers and user
reports are also used to evaluate link parameters. Bad weather,
equipment, operator errors, satellite problems, and intentional or
unintentional interference may cause problem conditions. The GMF
controller detects and analyzes network problems. The next step is to
direct work-around solutions. These solutions may be temporary power
adjustments, reduction-in-link capacity (drop out by priority) or
instructions to operators. In some cases, it may be necessary to
interrupt service for major maintenance actions. The GMF controller
maintains a log of all problems and terminal faults. A network status
display printout is also maintained. The status display printouts that
are available in the SAMS data base are status and statistics reports.
These reports are available as a hard copy, a cathode ray tube (CRT)
display, both on command, or at regularly timed intervals.
(1) The status report displays the condition of authorized
carriers under control of the AN/MSQ-114. This is done by a measured
carrier to noise temperature ratio (C/KT) reading, a calculated energy
per bit to noise density ratio (Eb/No), an operating noise temperature,
an authorized C/KT and a percentage of satellite allocated power for
each terminal. A summary page of the status report shows-Measured percentage of transponder power.
Allocated percentage of transponder power.
Measured percentage of GMF power.
Measured transponder C/KT.
(2) The statistics report is generated for a given start and stop
time frame with an established number of samples taken. For each terminal
under control of the AN/MSQ-114, the report shows-Mean C/KT (dB).
Authorized C/KT (dB).
Departure from authorized C/KT (dB).
Highest C/KT and time measured.
Lowest C/KT and time measured.
Number of samples taken.
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d. Often, during network operations, it may be necessary to
reconfigure a real-time link or the whole network. Some of the causes
for reconfiguration are:
Rapid terminal relocation.
Enemy action.
Degradation of a link.
Changes in communication requirements.
e. Reconfiguration by adding or deleting terminals is done by
the GMF controller. This involves changes to the SAMS data base and
coordination with the tactical terminal by orderwire. Terminal
relocation requires immediate action by the controller to coordinate the
movement. New system parameters and look angles must be provided and the
SAMS data base updated. Adding a new type earth terminal and using a new
satellite also requires reconfiguration. The GMF controller has the
authority to reconfigure the network until changes in satellite power or
new frequency assignments are required; then, the GMF manager must be
informed of the change required. The DSCS controller is responsible for
the DSCS satellite communications network. Since the GMF network is
only a subnet, the GMF controller must interface with the DSCS controller
when any action that takes place might impact on network performance.
Coordination is normally required-Before GMFSC terminals come on the air.
When changes in GMFSC transmit power are required.
When serious link degradations occur that cannot be isolated
by the GMF controller.
f. A more serious condition is when the DSCS controller informs
the GMF controller that violations have taken place in the GMFSC network.
As mentioned previously, a major duty of the GMF controller is to
monitor the uplink and downlink characteristics of the GMFSC network for
out of tolerance conditions. The result of this monitoring is to help
TACSAT communications terminal operators find stations that are at fault
and correct the problems. In severe cases, such as satellite failure or
interference, the DSCS controller must help pinpoint and rectify the
problem. The GMF controller, closely coordinating with the DSCS
controller, directs and implements network antijamming plans.
Control and Management
TACSAT communications links are not independent, unlike
conventional radio communications such as HF or LOS. All links in a
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network use the same satellite transponder. Each of the users must
carefully configure their link with reference to other users and keep
uplink power within an allotted level. Failure to follow these
guidelines will have harmful consequences on all other users. The
increase of power on one link improves the quality of that link but
intermodulation products increase and cause interference on the other
links. A large increase in power causes the downlink carriers on other
links to be suppressed. Control of all links using the same satellite
transponder is important. While the GMF controller is a major player in
the operation, overall control is distributed among six activities.
Those responsible for controlling the GMF/TACSAT communications
resources are described in the following paragraphs.
a. The planner plans the action and provides the following
information when establishing a communications link using a DSCS
Types of terminals and locations.
Connectivity of the network (for example, terrestrial,
switchboard, and direct interface).
Channel requirements.
Duration of exercise.
Priorities for individual links.
Backup communications.
b. The GMF manager is responsible for managing the satellite
resources allocated to the GMFSC. The manager combines all requests and
coordinates any conflicting requirements by-requester.
Apportioning a share of the satellite resources to each
Designating uplink and downlink frequencies, transmit power
levels, data rates, C/KT and bit error rates, link margins, and detailed
equipment settings.
Issuing orders for reconfiguring the system due to changing
Maintaining logs of system and station failures, interference
problems, and violations by the users.
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Interfacing with the DSCS controller to determine proper
Negotiating for extra power for the GMFSC users as the
situations warrant.
c. The DSCS controller is responsible for the DSCS network. This
encompasses all users including GMF terminals working a particular
satellite. The DSCS controller-Closely coordinates with the GMF controller during start and
antijamming procedures.
Informs the GMF controller when violations occur on the GMFSC
Links up with the GMF controller on the control orderwire.
d. The GMF controller operates under the direct supervision of
the GMF manager. The controller operates and maintains the control and
monitoring equipment. The GMF controller-Establishes a positive control with each terminal over the
control orderwire.
Starts communications links within parameters provided by the
GMF manager.
Monitors systems and link performance.
Controls adjustments of links to satisfy performance
Instructs violators to operate within assigned parameters and
reports willful violations.
Analyzes system and station malfunctions.
link with GMF operators and DSCS
Analyzes jamming signals and interference to determine
corrective actions.
Determines frequency compatibility when terminals are
Assigns previously cleared frequencies to another user when
interference in the network is present.
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e. The TACSAT communications terminal operator interfaces
directly with the GMF controller. The user or operator follows
instructions and reports status and performance of the TACSAT
communications terminal. The operator-Operates and maintains the TACSAT communications terminal.
Follows the GMF controller’s instructions and coordinates
during link start for reconfiguration, and at the same time isolates
system malfunctions.
rate (BER).
Monitors uplink power, downlink signal levels, and bit error
Relocates TACSAT communications terminal on proper command.
Notifies the GMF controller of the move time and new terminal
Interfaces with technical control of the subscriber.
System Configuration
a. The GMFSCCC is deployed in a number of different system
configurations depending on the mission and theater of operations. The
simplest configuration is point-to-point, where the GMF controller
monitors over two TACSAT communications terminals each used as a point.
The slightly more complex network is the hub-spoke configuration. Each
low capacity terminal becomes one of the spokes operating with either
the AN/TSC-85( ) or AN/TSC-100A. The hybrid configuration deals with a
number of hub-spoke configurations with the hubs communicating with each
other as well as the spokes in their configuration. A DSCS terminal (a
fixed station satellite communications facility called gateway) can
replace a low capacity GMF terminal. In these configurations, the
AN/MSQ-114 has an orderwire control link with all the TACSAT
communications terminals and a monitor link to the satellite. The
AN/MSQ-114 can communicate with a DSCS terminal via the terrestrial
critical control circuit (TCCC) network using either an established
terrestrial link or a communications circuit via the satellite. To make
DSCS terminals compatible with GMFSC terminals, additional equipment
must be included in the digital communications subsystem (DCSS) of the
DSCS terminal. The GMF contingency rack 20 low rate initial production
(LRIP) and GMF contingency rack 20A are single racks giving limited
operational capabilities to the DSCS terminals in the GMF network. To
enhance the capabilities, additional racks are added to produce the
DSCS/GMF gateway racks. Included are encryption devices, antijamming
modems, LRMs, and patch panels. The complement of racks is increased to
six in this configuration.
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b. The AN/MSQ-114 terminal consists of an environmentally
controlled 34-foot semitrailer, two power generators, a 20-foot
parabolic antenna, prime movers, and a shelter for maintenance and
storage of spare parts. The AN/FSQ-124 consists of four electrical
racks, a roll-around cart, and a control console in the facilities of
the host terminal.
c. The AN/MSQ-114 antenna is a 20-foot parabolic antenna type
AS-3199/TSC. It has a limited motion of ±l0° cross elevation and a full
90° in elevation. Antenna control can be from inside of the van or
remote. The modes of operation provided are manual, acquisition, and
auto-track. To acquire a satellite, the antenna must be implaced with
the azimuth look angle very close to the bore sight of the feed system.
(1) The receive subsystem consists of redundant antenna mounted
low noise amplifiers (LNAs) with 37-41 dB gain each and the downconverters. The receive signal is processed from the LNA to a power
divider that provides an eight-way split. Two of the outputs from the
divider are dedicated to the SAMS equipment. Five are connected to five
down-converters. The eighth is reserved for future addition of a sixth
(2) The down-converters are a double conversion type with a 70
MHz output. Frequency selection for the down-converters is accomplished
by front panel controls or by a microprocessor in an associated orderwire
modem in the remote mode. Three down-converters can feed the AJ/CM with
a beacon/CCC signal , an acquisition signal, and a polling signal.
(3) The cesium beam standard , which is the principal part of the
frequency generation subsystem, is also redundant. The on-line unit
provides outputs of 5 MHz, and one pulse per second for precise timing
to the AJ/CM and other units as needed.
(4) The transmit subsystem consists of up-converters, amplifiers/
mixers, and power amplifiers (PAs). Redundancy is presented in the PA,
high voltage power supply, and amplifier/mixer assemblies. The PA has a
maximum power output of 500 watts with an adjustment range of 20 dB.
Three up-converters are provided with a future development for a fourth.
They accept a 70 MHz signal from the orderwire or AJ/CM modem. Through a
conversion process, the transmit frequencies are presented to the
intermediate power amplifier (IPA)/attenuator to be raised to a suitable
power level for driving the PA.
d. The AN/FSQ-124 is a component of a DSCSOC which is collocated
with a host earth terminal. The host earth terminal can be an AN/GSC-39,
an AN/GSC-52, or an AN/FSC-78. The AN/FSQ-124 consists of a remote
orderwire console and four equipment racks that contain up- and downconverters, SAMS, IPAs, and orderwire modems. The AN/FSQ-124 is operated
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and maintained by a specially trained operator who is one of the five
individuals normally on shift in the DSCSOC.
Antijamming and ECCM Techniques
a. The AN/MSQ-114, acting as the NCT, has the AJ/CM (MD-1133)
that belongs to a family of spread spectrum modem equipment designed to
provide the GMFSC terminals with ECCM capability for operation in a
stressed environment. The spread spectrum link provided by the AJ/CM is
more difficult to jam. This signal can coexist with the FDMA links by
sharing the same frequency spectrum and presenting the appearance of not
even being there. This link may well be the last ditch signal available
in a stressed environment.
b. The MD-1133 used in the AN/MSQ-114 consists of one chassis
assembly, the NCU. The NCU has a control and bus logic which provides
functional terminal modem organization, execution, and control. The NCU
control processor directs external programmable up-/down-converter
synthesizer frequency control. The NCU requires a precise frequency and
time reference from an external cesium beam standard. Redundant frequency
standards (HP5061A), which are part of the AN/MSQ-114, provide the
required time and frequency references. The NCU provides buffering for
time and frequency reference signals for computational and code use.
Software is modularized to specific terminal operations and functions.
Terminal tasks are modularly executed through combinations of software
modules, operator control, and fixed microprocessor hardware logic.
Network control and status functions are provided on the NCU front panel
along with monitor test and fault isolation functions. The AJ/CM
replaces the RT-1287 nonsecure FM orderwire. It operates as an orderwire
between the NT in addition to its communication’s function. In a jammed
environment, the AJ/CM equipment provides the antenna tracking signal
instead of normal communications tracking.
Data Entry
a. The SAMS element of the AN/MSQ-114 and the AN/FSQ-124
provides the data base for planning GMF resources. The SAMS also
provides the monitor facilities for managing the GMFSC network. The SAMS
supports the GMF controller in translating satellite communications
(SATCOM) requirements into channel capacities, time schedules,
transmitter power, RF frequency assignments, and modes of operation. The
SAMS monitors and measures the technical performance of deployed GMF
ground terminals. This allows missions to be accomplished with a minimum
assignment of available RF power and bandwidth. It also helps determine
compliance of GMF ground terminal with assignments.
b. Network management is done by the SAMS software which consists
of various resource planning, measuring, calculating, and report
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generating programs. These programs present to the GMF controller a
real-time description of the satellite downlink.
c. The major parameters to be measured and calculated include
carrier-to-noise density (analog and digital signals received by the
AN/MSQ-114 and AN/FSQ-124 terminals), operating noise temperature, and
percentage of satellite power usage. Alarm conditions and statistical
data are also presented to the controller as conditions dictate and/or
as required. A real-time operating system controls the SAMS software
modules and data bases.
d. The SAMS uses all of the hardware , under control of computer
programs, to perform the following required functions:
Plan GMF links.
Monitor the GMF downlink spectrum.
Produce summary reports.
Interact with the operator through a user friendly man-machine
Maintain a large data base for use in the planning and
monitoring function.
Manage all operations.
e. The GMF controller makes SAMS data base entries which are
directly related to the AN/MSQ-114 and the AN/FSQ-124 functions. These
functions are monitoring and controlling the GMFSC networks. The
information to be entered comes from the DCA planner and the GMF manager
in the DSCS-GMF SAA. This information is entered into the SAMS data base
via the keyboard or by prepared cassette tape(s). The following examples
of an SAR, sample report 1 (Figure 5-5), and DSCS-GMF SAA, sample report
2 (Figure 5-6), are the worksheets from which data to be entered into
the SAMS is taken. The SAR must be in accordance with Defense
Communications Agency operations center (DCAOC) contingency/exercise
plan. (All entries on these worksheets are fictitious although
representative of actual data.)
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Chapter 6
System Description
a. The Army’s tactical C communications must be reliable, long
range, transportable, and secure. These communications must survive in
severe EW/NBC environments where ground relay networks that use prominent
terrain may be disrupted. They must support the critical communications
needs of the tactical commander. The Milstar satellite communications
system provides these capabilities. It integrates satellite
communications with an ECCM capability and balanced nuclear hardening
into ground terminals for installation and operation in communications
shelters. The Milstar satellite communications system provides the most
survivable communications link on the battlefield in both intense
jamming and nuclear environments.
b. The AN/TSC-124 will be the Army’s Milstar terminal. It will
be fielded in Army units in the early 1990s. It will provide antijamming
interoperable satellite
communications to support critical C communications. Exclusive of the
SCS, the AN/TSC-124 does not replace existing communications
on the battlefield; it augments the existing terrestrial C nets when
other communications means are degraded or destroyed. The traffic
transmitted via the AN/TSC-124 terminals will normally be essential data
communications. Voice communications, though possible, are not intended
to be the primary method of communications through the Milstar system.
System efficiency decreases as voice traffic levels increase. Therefore,
data traffic will have a higher priority for channel access throughout
the system.
a. SCS. AN/TSC-124 terminals will replace AN/MsC-64s, currently
used within the SCS, to operate the Flaming Arrow Net in Europe and
b. Theater. At EAC in Europe and Korea, AN/TSC-124s will provide
for connectivity between the theater main, theater alternate, theater
Army main, theater Army alternate, the theater Army Milstar control
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center (TAMCC), and six discretionary headquarters such as major joint
or allied unit headquarters, additional CINC support and the like. The
theater TACSAT signal company will install, operate, and maintain the
c. Contingency support. The 235th Signal Detachment and 209th
Signal Company will each employ AN/TSC-124 terminals in support of Army
and JCS operations worldwide. They will augment the theater assets if
d. Special Operations Command (SOCOM). The l12th Signal Battalion
will employ AN/TSC-124 terminals in support of SOCOM operations.
The AN/TSC-124 will be a commander’s asset. Although regular and
recurring association of terminals and headquarters will occur, the
terminals can be employed at the commander’s discretion. The commander
can assign a priority of communications and fight the communications
assets as a combat multiplier like any other weapons system.
a. Nets and networks. The unique characteristics and
capabilities of the terminals and associated satellite systems make
structured nets unnecessary. Because the terminals operate with a DAMA
technique, there is no requirement for dedicated channels. Because of
the processing capabilities of the satellites and the ability to address
discretely any terminal within the system, Milstar terminals can
communicate with any other Milstar terminals, whether located within the
same theater of operations or not. Different protocols, however, will be
required for in-theater and out-of-theater communications. For network
identification and TRANSEC key management, all AN/TSC-124 terminals
operating within the Army spotbeam footprint on each satellite will make
up a network. Therefore, separate nets are unnecessary. However,
partitions may be formed by selecting and distributing different COMSEC
keys and addresses to the users; for example, distributing like keys to
those users who want to operate together to the exclusion of others. The
discrete addresses would then be furnished in a format similar to the
telephone books now employed. Terminal-to-terminal connectivity would
remain possible, with end-to-end communications being possible only if
like COMSEC keys are employed at each 1/0 device.
System characteristics.
(1) The AN/TSC-124 will consist of the terminal, prime mover,
antenna, and trailer-mounted power generator. The AN/TSC-124 will be
installed in one S-250 or equivalent shelter. It will be transported
under tactical conditions by a standard 1 l/4-ton truck. A 3 kilowatt
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generator will be mounted on a standard 3/4-ton trailer that will be
towed by the prime mover. Backup power will be provided by an under-hood
power plant installed on the vehicle.
(2) The terminal can communicate at the halt; communicating while
moving is a planned improvement that will come with future technology.
Terminal setup and teardown times will not exceed 30 minutes by a team
of three MOS 31C soldiers.
(3) Critical, operator-replaceable spares will be carried to
enhance system survivability and ensure rapid repair and return to
service. Additionally, crew, crew weapons, personal bags and equipment,
camouflage netting, tents, and the like will be carried on the vehicle
or in the terminal. C130/C141/STOL aircraft roll-on/roll-off with no
preparation is possible.
(4) The terminal will be able to accept up to four individual
user inputs of data or voice at rates of 75 bps to 2.4 kbps by using
user-controlled interface devices (UCIDS). The devices can be remoted
2,500 feet (758 meters) from the terminal using conventional field wire.
Four DR-8s, modified to accept and dispense WF-16 field wire, will be
provided with the terminal. The DR-8s will provide a minimum remoting
capability independent of customer field wire resources.
(5) Compatibility with the Milstar standard I/O and COMSEC
devices (for data, the AN/UGC-74 and KG-84; for voice, the ANDVT) as
well as the single subscriber terminal (SST), lightweight digital
facsimile, and the Army Command and Control System (ACCS) hardware is
provided. Each terminal will be furnished with one AN/UGC-74 and one
ANDVT for operator use.
(6) It will be hardened to the effects of electromagnetic pulse
(EMP)/high altitude EMP (HEMP) and will operate in EW/NBC environments.
(7) The system will adapt to changes in the jamming environment
and changes in traffic demands regardless of environment. The terminal
will use spread spectrum, burst, FH, and other techniques to reduce the
vulnerability to RDF, interception, exploitation, and jamming. The
AN/TSC-124 will be interoperable with all other Milstar terminals.
c. User-controlled interface device.
(1) UCIDs interface between the user of the I/O device and the
terminal. It can accept inputs between 75 bps and 2.4 kbps and support
full-duplex communications. The user requests service through the UCID.
The UCID lets a user tell the terminal which specific I/O and COMSEC
devices are attached to the two ports of the UCID. Information relating
to the service requested, discrete addresses of sender and receiver(s),
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and I/O device and COMSEC compatibility can be entered by the user. This
alerts the terminal and the servicing satellite to establish the
requested type of link between the sender and receiver(s). Once the link
is established, the UCID must alert the sender that he may pass his
(2) Four UCIDs will be provided with each AN/TSC-124. Each can
accept two inputs, though not at the same time. Three UCIDs will normally
be provided to the remote users. The fourth UCID will be reserved within
the shelter to allow the AN/TSC-124 operator access to the system for
the operator I/O devices provided with the terminal (AN/UCG-74 and
(3) The UCID can be used by a general purpose user (GPU) of any
grade or MOS. The UCID, although a component of the AN/TSC-124 terminal,
will be provided to the user at the user’s remote location. The UCID,
associated COMSEC (that is, KG-84), and user-owned and provided I/O
device will be operated by the user of the communications provided by
the terminal.
Control and Management
(1) The USAF Milstar ground command post terminal (GCPT), the
Navy EHF Satellite Program (NESP), and the Army SCOTT (AN/TSC-124)
provide the services with control and access to the Milstar satellite
constellation to support the National Command Authority.
(2) The Milstar mission control element, called the theater
Milstar control center (TMCC), will exercise overall control within a
theater of operations along with a number of constellation control
stations. The specific roles for each and the requirements for interface
are being developed by USAF Space Command. The Army Space Command is
refining the specific responsibilities and procedures for Army-specific
Milstar control.
TRANSEC/COMSEC management.
(1) The National Security Agency (NSA) distributes the TRANSEC
keys. As part of the initial terminal start-up, the TRANSEC variables
are distributed to the units’ COMSEC accounts and the operator manually
loads the TRANSEC keys. Before the TRANSEC period expires, the mission
control element (MCE) distributes, over the air, the keys for the
upcoming TRANSEC period. Emergency rekey also occurs over the air (for
example, when a network terminal is compromised). Backup and future
TRANSEC keys should be on hand with the unit COMSEC custodian to
facilitate rekey in the event over-the-air rekey is not possible.
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(2) The COMSEC keys are distributed to individual COMSEC accounts
for dissemination to individual terminal users. Both the normal and
emergency rekey for data and voice COMSEC devices are done manually.
Backup and upcoming keys are on hand at the terminal-user locations. The
number of variables issued to each terminal and user depends on the
mission of that terminal or user and the network in which it operates.
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Chapter 7
UHF Air Force Satellite Communications
System Description
a. AFSATCOM provides reliable, worldwide, C communications.
These communications are used by designated Single Integrated Operational
Plan (SIOP)/nuclear capable users for emergency action message (EAM)
dissemination, JCS-CINC internetting, force direction, and force reportback. AFSATCOM capacity is also provided for a limited number of high
priority non-SIOP users for operational missions, contingency/crisis
operations, exercise support, and technical/operator training.
b. The AFSATCOM system is made up of a space segment. This space
segment consists of UHF transponders aboard several spacecraft and a
terminal segment. The terminal segment consists of standard AFSATCOM
ground/airborne, manpack, and special communications system terminals.
The space segment is Air Force managed transponders of varying
capability and capacity. They are carried aboard the fleet satellite
communications (FLTSATCOM), leased satellite communications (LEASATCOM),
satellite data systems (SDS), Packages B and C, DSCS III, and Lincoln
experimental satellites (LES) 8 and 9.
System Communications Control Hierarchy
The Air Force Communications Command (AFCC) controls system
communications as directed by the AFSATCOM program management directive
(PMD). Figure 7-1 shows the hierarchy of control elements as follows:
System operational management office (OMO).
Master control center (MCC).
Primary control center (PCC).
Network control element (NCE).
of control.
The AFSATCOM control objectives-Provide the operator/user with communications with a minimum
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Schedule satellite accesses in keeping with current system
limitations, equipment constraints, and validated priorities.
Prevent users from interfering with each other and/or
disrupting the integrity of the system.
Manage the number and power of satellite accesses ensuring
sufficient downlink power margin to those users authorized to operate.
Provide a control subsystem with enough equipment to monitor
satellite communication transponder operations and to recognize and
assist with operational or technical system problems.
Provide high priority users reliable communications during
crisis or contingencies.
b. The Chief of Staff, United States Air Force (CSAF) is the
executive agent for the management and control of AFSATCOM. The
Strategic Communications Division (SCD) is designated the AFSATCOM
operational manager for the commander, AFCC. The SCD manages the
AFSATCOM satellite system on a day-to-day basis, interacting directly
with the Navy telecommunications command (NAVTELCOM) on control
procedures involving both services.
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Access Requests
Access requests should be submitted to the appropriate PCC at
least 14 days before the requested start time of the access. If a ground
entry point (GEP) (AN/FSC-82) is part of the access, an additional 14
days are required for coordination. PCCS normally begin preparing access
schedules 30 days in advance to allow for changing user requirements.
Routine access requests must be submitted between 14 and 30 days before
requested access start time. Access request may be submitted earlier if
lead-time is required for host nation frequency approval. Frequency
approval should be requested for all AFSATCOM frequencies in the
operating area. (See Tables 7-1 through 7-11.)
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a. AFSATCOM access request format. The AFSATCOM access request
format has two parts. Part 1 is used for general information required to
coordinate the access: times, dates, locations, points of contact,
narrow or wideband transponder use, power, and bandwidth. Part 2 is used
for GEP (AN/FSC-82) access. Figure 7-2 shows the format to request
access of the AFSATCOM space segment. First time requests from Category
1 users and all requests from Category 2 must contain Parts 1 and 2. T O
request changes or extensions, use only the parts containing changed
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Part 1 —General Request Information
1. Requesting agency and location. User requirements data base (UROB)
line number and net name (acronym).
2. Number and type of accesses (for example, narrowband, regenerative,
nonregenerative, ”wideband, fixed frequency access, AFSATCOM wideband address code).
3. Purpose of access. This section must accurately describe the mission/
requirement/purpose insufficient detail to equitably assign user priorities.
Failure to provide accurate purpose information could result in a lower
priority assignment than actually required or delays in access request
processing while additional information is gathered.
4. Geographical limits of access (location of ground stations and maximum/
minimum latitude/longitude of airborne terminals).
5. NCE location and using agency, “if different from item 1.
6. Staff POC and/or NCE point-of-contact (person/operations center/CP
having immediate contact with NCE)-primary and alternate names and
AUTOVON (if overseas, indicate AUTOVON area code). (THESE CONTACTS
7. Access period(s) start and stop times (ZULU). (Indicate acceptable alternate
time periods if possible.)
8. Modulation type and data rate,
9. Terminal(s) characteristics:
a. Terminal type/nomenclature.
b. Transmitter output (watts—fixed or variable, maximum/
minimum) or maximum effective isotropic radiating power (EIRP).
c. Antenna nomenclature and gain (in dB) in all cases and manufacturer (if not a standard AFSATCOM antenna).
d. Receiver G/T (dB) (receiver system figure of merit).
e. Required Eb/No (dB) for data rate or FM signal-to-noise ratio.
f. Modem type/nomenclature.
10. Remarks: Name and AUTOVON number of requestor, if different from
item 6. If access was approved by phone, name of person contacted. If
request is priority 4 or higher, name and office symbol of individual from
whom approval was obtained. If request is to extend or modify an existing
access, the access authorization number of the original approval. Other
information as necessary.
Figure 7-2. AFSATCOM access request message format parts 1 and 2.
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Part 2—GEP (AN/FSC-82) Access
11. GEP required (location).
12. Dates/times (ZULU) of requirement for GEP.
13. Type of interface required (voice or data).
14. Type of encryption device at deployed location.
15. Highest classification of traffic to be passed.
16. Specific end item required at GEP terminal (for example, KY-57, KY-65,
UYA-7, UGC-1 29).
17. Intended termination at GEP (for example, AUTOVON, NMCC, Washington
Switch, dedicated circuitry).
18. Remarks: Other specific information which will help the ground terminal
manager meet your requirements.
Figure 7-2. AFSATCOM access request message format parts 1 and 2.
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b. Access request addressees. The access request should be
addressed to the PCC controlling the desired satellite. All access
requests should also inform the remaining PCCS, the MCC, and the OMO. If
the request is for a priority 4 or higher, JCS/C3SDS must also be
included as an information addressee. Requests which include
requirements using a GEP should also inform that agency and their
intermediate headquarters. Table 7-12 lists all current message
Exercise Access Request
The supported unified or specified command for all supporting and
component commands validates, consolidates, and submits satellite access
requests for JCS-named, -coordinated, and -directed exercises. (See JCS
Publication 2.) Heavy exercise communications traffic causes increased
loading of the AFSATCOM system. Before a scheduled exercise, the
exercise office of primary responsibility (OPR) notifies the MCC of the
exercise scheduled time frame, geographical scope, and of the expected
AFSATCOM channel requirements. This information should arrive at the MCC
at least 45 days before the exercise start time. If military satellite
communications (MILSATCOM) channels are unavailable to support all
exercise requirements, the sponsoring CINC prioritizes and recommends
allocation of the approved exercise satellite accesses in support of
exercises in the CINCS area of responsibility (AOR). Requests for
satellite access for unit or major command exercise communications (not
in support of JCS-directed or JCS-coordinated exercises) should continue
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to be coordinated directly between the requestor and the PCC unless
otherwise directed by the theater CINC. Guidance for submitting JCSnamed exercise satellite access requests as provided by the various
CINCS follows:
a. USCINCEUR. To obtain UHF SATCOM support for exercises within
the European theater, supporting units submit access requests through
CINCUSAREUR Heidelberg GE//AEAIM-PA-PE//: AUTOVON 370-6868/6646. The
USCINCEUR component commands review, validate, and consolidate all UHF
SATCOM access requirements for their subordinate command, and submit the
request to USCINCEUR Vaihingen GE//C3S-TSC//. AUTOVON is 430-8484/5416
or Secure 6416, drop 6.
b. USCINCCENT. To obtain UHF SATCOM support for exercises within
USCENTCOMS AOR, supporting components submit access requests to
USCENTCOM components commands as follows:
Any Army component: COMUSARCENT Fort McPherson GA//AFRD-CE//;
AUTOVON 588-4825/4928.
Any special operations component: SOCCENT MacDill AFB FL//
SOCJ6//; AUTOVON 968-6256.
USCENTCOM component commands review, validate, and consolidate all
access requirements and submit them to USCINCCENT MacDill AFB FL//
CCJ6-CM//; AUTOVON 968-6600, Secure 9163.
c. USCINCPAC. To obtain UHF SATCOM support for exercises within
the Pacific theater, supporting units submit access requests to
USCINCPAC component or subordinate unified commands as follows:
Army units (exclusive of Korea and Japan forces): CDR WESTCOM
Fort Shafter, Hawaii.
US Forces in Korea: COMUSKOREA Seoul KOR//SJ-OPO//.
US Forces in Japan: COMUSJAPAN Yokota AB JA//C3S//.
The component commands or subordinate unified commands review, validate,
and consolidate all UHF SATCOM access requirements for their units. They
submit these requests to USCINCPAC Honolulu HI//C3S// about 30 days
before the exercise starts. This allows enough time for coordination.
POC AUTOVON 477-6715/6644.
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d. USCINCLANT. To obtain UHF SATCOM support for exercises within
USCINCLANTS AOR, subordinate forces submit access requests to USCINCLANT
component commands as follows:
Special operations forces:
AUTOVON 236-2213.
Army forces:
AUTOVON 588-4129/2239 .
COMSOCLANT Fort Bragg NC//36//;
USCINCLANT components, Joint Headquarters (CJTF/COMUSFORCTRY), and
collect, consolidate, review, and validate exercise AFSATCOM access
requirements and submit them as a single package to USCINCLANT Norfolk
VA//J62l//; AUTOVON 564-6761.
(1) Components and supporting commands/agencies provide an
initial estimate of their access requirements during the initial planning
(2) USCINCSO/SCJ6-0 consolidates all requirements and makes
initial coordination with the AFSATCOM management office appropriate PCC
during the planning process.
(3) Components and supporting commands provide a final statement
of their requirements. It is prepared in the AFSATCOM access request
format and sent to USCINCSO Quarry Heights PN//SCJ6-0//, AUTOVON 313282-3252, no later than 60 days before the access start time.
e. USCINCSO. USCINCSO/SCJ6-0 acts as the central point for all
AFSATCOM accesses for any USCINCSO sponsored, JCS-directed, or JCScoordinated exercise within CINCSO AOR. USCINCSO/SCJ6-0 prioritizes and
consolidates requirements and forwards them to the appropriate PCC.
f. USCINCSPACE. When CINCSPACE has been designated as the
sponsoring CINC for JCS-directed or JCS-coordinated exercises,
CINCSPACE/J3Z, AUTOVON 692-2613, acts as the focal point for exercise
support satellite access requests. Military satellite requirements in
support of the exercises are directed to CINCSPACE Peterson AFB CO//
J3Z// . CINCSPACE /J3Z reviews, validates, and consolidates all access
requirements and submits the request to the appropriate PCC. Approved
access requests are then assigned to the supporting commands and units
based on CINCSPACE determined priorities.
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Emergency Access Request
An emergency/short notice access can be coordinated by telephone.
These will be accepted if a properly formatted message traffic follow-up
is submitted within 24 hours of the initial telephone access approval.
Figure 7-3 shows the AFSATCOM access approval/disapproval message
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Abbreviations and Acronyms
air base
area coverage
Army Command and Control System
Air Force Base
Air Force Communications Command
Air Force satellite
Air Force satellite communications
antijam/control modem
advanced narrowband digital voice terminal
area of responsibility
antenna pallet transit frame
army regulation
Army Space Institute
automatic voice network
automatic secure voice communications
bit error rate
bits per second
biphase shift keying
command, control, and communications
critical control circuit
combined ground command post terminal
Commander in Chief
Commander in Chief, United States Army Forces,
Commander in Chief, United States Army, Europe
Commander Joint Task Force
carrier to noise temperature ratio
Commander, Iceland Defense Force
communications security
Commander, Special Operations Command, Atlantic
Commander, United States Army, Central
Commander, United States Forces, Azores
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Commander, United States Forces, Caribbean
Commander, United States Forces, Country
Commander, United States Forces, Japan
Commander, United States Forces, Korea
continental United States
corps support command
command post
Confidential Restricted Data
cathode ray tube
Chief of Staff, United States Army
Chief of Staff, United States Air Force
counter-signals intelligence
communications system planning element
control terminal
commercial utility cargo vehicle
Department of the Army
demand assigned multiple access
District of Columbia
Defense Communication Agency
Defense Communications Agency Circular
Defense Communications Agency Operations Center
Defense Communications System
digital communications subsystem
division support command
digital message device group
Department of Defense
direct sequence
Defense Satellite Communications System
Defense Satellite Communications System Operations
data terminal equipment
echelons above corps
emergency action message
Eastern Atlantic
Eastern Pacific
energy per bit to noise density ratio
earth coverage
electronic countermeasures
electronic counter-countermeasures
extremely high frequency
effective isotropic radiating power
electromagnetic pulse
electronic warfare support measures
electronic warfare
frequency division multiple access
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frequency hopping
fleet satellite
fleet satellite communications
frequency modulated/field manual when used with
a number
frequency shift keying
force terminal
Ground Command Post Terminal
gimballed dish antenna
ground entry point
ground mobile forces
ground mobile forces satellite communications
GMF satellite communications control center
GMF network controller
general purpose user
general support
ratio of antenna gain to noise temperature
high altitude, EMP
high frequency
intermediate frequency
United States Army Intelligence and Security
Indian Ocean
intermediate power amplifier
Joint Chiefs of Staff
Joint Communications Satellite Center
Joint Chiefs of Staff Memorandum of Policy
kilobits per second
link communications circuit
leased satellite
leased satellite communications
Lincoln experimental satellites
low noise amplifier
line of sight
low rate initial production
low rate multiplexer
master control center
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mission control element
military intelligence
military satellite communications
memorandum of policy
military occupational specialty
Mobile Subscriber Equipment
not applicable
Navy telecommunications command
nuclear, biological, chemical
narrow coverage/North Carolina
narrow coverage/area coverage
network control element
network control function
net control station
network control terminal
network control unit
Navy EHF satellite Program
National Military Command Center
National Military Command System
non-nodal terminal
net radio interface
National Security Agency
nodal terminal
Official Use
operational management office
operational control
operation plan
operation order
office of primary responsibility
power amplifier
primary control center
program management directive
point of contact
phase shift keying
quadraphase shift keying
quick reaction satellite antenna
radio direction finding
radio electronic combat
radio frequency
Regional Space Support Center
satellite access authorization
satellite automatic monitoring system
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satellite access request
satellite communication(s)
strategic communications division
single-charnel objective tactical terminal
Special Communications System
satellite data systems
super high frequency
signals security
Single Integrated Operational Plan
satellite network controller
Special Operations Command, Central
Special Operations Command
single sideband
spread spectrum multiple access
single subscriber terminal
tactical satellite
theater Army Milstar control center
training circular
terrestrial critical control circuit
time division multiple access
theater Milstar control center
technical order
table(s) of organization and equipment
United States Army Training and Doctrine Command
transmission security
Tri-Service Tactical Communications
tracking, telemetry, and control
user-controlled interface device
ultra high frequency
Unified Action Armed Forces
user requirements data base
United States (of America)
United States Air Force
United States Army Information Systems Command
United States Army Space Command
United States Central Command
United States Commander in Chief, Central
United States Commander in Chief, Europe
United States Commander in Chief, Atlantic
United States Commander in Chief, Pacific
Commander in Chief, United States Southern
United States Commander in Chief, Space Command
United States Space Command
Vice Chief of Staff, United States Army
very high frequency
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United States Army Western Command
Western Atlantic
Western Pacific
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BIPHASE SHIFT KEYING (BPSK). Modulation process whereby the phase
of the subcarrier is discretely varied in relation to phase of previous
signal element by two modulating signals 180 degrees out of phase.
CRITICAL CONTROL CIRCUIT (CCC). The orderwire link, commonly spread
spectrum, used by the NCT to provide command and control to each of the
NTs and to receive status/replies.
CROSS-ELEVATION. The sector of antenna movement in azimuth from an
initial emplacement position due to limits imposed in antenna drive
DATA BASE. A collection of necessary operational data entered into
a computer that can be retrieved with speed and ease in different
FOOTPRINT. Coverage patterns of satellite antennas on portions of
the earth’s surface.
GEOSTATIONARY. As applied to a satellite located at an altitude of
approximately (35,000 kilometers) over the equator traveling at a rate
of speed to appear stationary with respect to a point on earth.
LOOK ANGLE. Azimuth and elevation angles necessary for a terminal
antenna position to access a satellite (LOS to satellite).
MILSTAR. A new generation satellite communications system designed
to meet the minimal essential wartime communications needed to satisfy
specified strategic and tactical mission requirements.
NET. An organization of terminals capable of direct communications
with each other using a common frequency or channel for a common
NETWORK. An organization of terminals capable of communication
with each other but not necessarily on the same frequency or channel for
a common purpose.
NODAL. The terminal situated at the hub of a net (AN/TSC-85( ) or
AN/TSC-100A) passing communications to a number of terminals.
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QUADRAPHASE SHIFT KEYING (QPSK). The modulating of a subcarrier by
four signals 90 degrees out of phase. Two times as much intelligence
for the same bandwidth as BPSK.
SPREAD SPECTRUM. A special digital modulation process in which the
carrier is suppressed and the signal is distributed over the entire
TERRESTRIAL. Pertaining to the earthbound communication other than
by satellite (that is, land line, wireless, LOS).
TRANSPONDER. Name applied to satellite or devices in satellite to
receive and retransmit communications signals.
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Required Publications
Required publications are sources that users must read in order
to understand or to comply with this publication.
Defense Communications Agency Circulars (DCACS)
Operation and Control of the Defense Satellite
Communications System (DSCS)
Satellite Communications Reference Data
Handbook, Volumes I and II
Field Manual (FM)
Tactical Single-Channel Radio Communications
Joint Chiefs of Staff Memorandum of Policy (JCS MOP)
Military Satellite Communications Systems
Training Circulars (TCS)
(CRD) COMSEC Applications for Tactical
Satellite Communications
Tactical Multichannel Radio Communications
Signal Data References: CommunicationsElectronics Equipment
Related Publications
Related publications are sources of additional information.
They are not required in order to understand this publication.
Army Regulation (AR)
Department of the Army Information Security
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Field Manuals (FMs)
Theater Communications Command (Army)
Signal Tactical Satellite Company
Combat Communications Within the Division
(How to Fight)
Telecommunications Engineering: Digital
Combat Communications
Counter-Signals Intelligence (C-SIGINT)
Joint Chiefs of Staff Publication (JCS Pub)
(0) Unified Action Armed Forces (UNAAF)
Training Circular (TC)
Jamming Handbook
Technical Manuals (TMs)
Operator’s, Organizational and Direct Support
Maintenance Manual for Satellite
Communications Set, AN/USC-28(V)
Operator’s Manual for Satellite Communications
Terminal, AN/MSC-64(V)2
Operator’s Manual for Satellite Communications
Terminal, AH/TSC-93A
Operator’s Manual for Satellite Communications
Terminal, AN/TSC-85A
Operator’s Manual for Radio Set AN/PSC-3
Operator’s and Organizational Maintenance
Manual Satellite Automatic Monitoring
Subsystem OL-325/FSQ
Operator’s Manual for Multiplexer, Digital,
TD-1337(V)l/G, TD-1337(V)2/G, TD-1337(V)3/G
and TD-1337(V)4/G
Technical Orders (TOS)
Satellite Communications Terminals
Satellite Communications Terminals
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