TOA Electronics Closed Circuit Television Systems

TOA Electronics Closed Circuit Television Systems
Closed Circuit Television Systems
Fundamentals Course
TOA Corporation
TOA Electronics, Inc. (USA)
www.toaelectronics.com
TOA Canada Corporation (CANADA)
www.toacanada.com
Contents
1.
CCTV SYSTEMS .......................................................................................................1
1-1.
What are CCTV systems?......................................................................................1
1-2.
What are security systems? ...................................................................................1
1-3.
How television works..............................................................................................2
1-4.
Television system...................................................................................................5
2.
CCTV SYSTEM DESIGN ...........................................................................................6
2-1.
Designing a CCTV system .....................................................................................6
2-2.
Aims of a surveillance camera system ...................................................................6
2-3.
System design elements ........................................................................................7
2-4.
Conditions for equipment selection ......................................................................10
2-5.
Camera installation .............................................................................................. 11
3.
CAMERA SELECTION ..............................................................................................16
3-1.
Types of cameras used in CCTV systems ...........................................................16
3-2.
Power supply systems .........................................................................................17
3-3.
Camera performance ...........................................................................................18
3-4.
Camera functions .................................................................................................20
3-5.
Synchronization methods.....................................................................................23
3-6.
Camera mounts....................................................................................................25
4.
LENS SELECTION ....................................................................................................26
4-1.
Angle of view settings ..........................................................................................26
4-2.
Lens mount ..........................................................................................................27
4-3.
Auto-iris lens ........................................................................................................27
4-4.
Types of lenses ....................................................................................................28
4-5.
Lens selection ......................................................................................................30
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5.
MONITOR SELECTION .............................................................................................31
5-1.
Monitors ...............................................................................................................31
5-2.
Reduced image scale on monitors .......................................................................32
5-3.
Notes on monitor installation ................................................................................33
6.
SWITCHER SELECTION & VIDEO RECORDING ......................................................35
6-1.
Sequential switcher ..............................................................................................35
6-2.
Multi-viewer..........................................................................................................36
6-3.
Matrix switcher .....................................................................................................36
6-4.
Multiplexer............................................................................................................37
6-5.
Time-lapse VCR recordings .................................................................................39
6-6.
Digital video recorders (DVR’s) ............................................................................40
7.
SENSOR TYPE SELECTION .....................................................................................41
7-1.
Infrared sensors ...................................................................................................41
7-2.
Passive sensors ...................................................................................................43
7-3.
Motion detectors ..................................................................................................43
8.
REMOTE-CONTROLLED SURVEILLANCE AND NETWORK CAMERAS ....................44
8-1.
Remote-controlled surveillance ............................................................................44
8-2.
Network camera system.......................................................................................45
9.
VIDEO SIGNAL AND CONTROL SIGNAL TRANSMISSION ........................................47
9-1.
Coaxial cables......................................................................................................47
9-2.
Twisted-pair cable transmission ...........................................................................48
9-3.
Control signal circuits ...........................................................................................48
9-4.
Electrical power construction requirements..........................................................51
10.
Making Drawings ..............................................................................................52
10-1.
Preparing block diagrams ....................................................................................52
ii
10-2.
CCTV drawing symbols........................................................................................53
Appendix Unit Conversion Table
iii
1.
CCTV Systems
1-1. What are CCTV systems?
Televisions systems are now one of the most indispensable information and communications means in our daily life. They can be broadly classified as shown in Figure 1-1, and
are used in a wide range of applications, including standard television broadcasts.
Television systems
Closed-circuit system
Closed-circuit system
CCTV
Open-circuit system
CATV
(a)Military, outer space, and aviation
(a)CATV
(b)Multimedia: Video conference, image processing, etc.
(b)Cable TV
(a)TV broadcast
(c)Medical care:
Gastro camera and operating room monitoring
(d)Production management and industrial measurement:
Product inspection, etc.
(e)Academic and special fields:
(f)Service:
TV education
Monitoring of attendance to customers
(g)Crime prevention:
Banks, Gaming parlors, etc.
(h)Disaster prevention:
Traffic control, river water flow monitoring, etc.
Figure 1-1. Television Systems
An open-circuit system refers to a system that is targeted at an indefinite number of
people, as in television broadcasts.Closed-circuit systems, on the other hand, are designed
to provide video to specified viewers. One closed-circuit system that is primarily designed
for surveillance purposes is generally called a closed-circuit television or CCTV system.
CCTV is used in a wide variety of applications which include security, disaster prevention,
energy and manpower saving, sales promotion and information services, production
management, industrial measurement, medical care, education and military fields.
1-2.
What are security systems?
Security systems are integrated systems made up of different types of equipment and
devices, the combined operation of which helps protect human lives, property, the environment and information. Crime prevention literally represents preventing violation of the
law and public interests and disturbances to social order through acts of crime, which
should be punished by law. Crime prevention facilities and equipment are classified as
shown in Figure 1-2. Long-distance picture transmission systems and surveillance camera
systems are encompassed within CCTV systems designed for crime prevention.
The aims of the installation of crime prevention facilities are to let criminals know the
risks of crime and function as a deterrent of crime or keep constant watch over potential
criminal acts. When a criminal act is detected, the facility’s sensors or emergency warning
1
switches are operated to sound an alarm and ideally cause criminals to go elswhere.
Thereafter, information is sent to related departments or personnel for taking appropriate
measures to avoid loss.
Crime
prevention
facility
Crime prevention environmental facility
Crime
Intrusion detection facility
System when
prevention
not attended by
warning
operators
facility
System when
attended by
At-home alert
operators
Manned surveillance
(concurrent use of machine security systems)
Entrance/ security system
Shoplifting surveillance system
Crime
prevention
equipment
Crime prevention surveillance facility
Alert equipment
Repulse equipment
Protection equipment
Other
Street light, etc.
Machine security system (security business = In-line system)
Intrusion-alarm system
Long distance warning system
Long distance picture transmission system
Intrusion-alarm system
Emergency warning system (including burglar alarm)
Interphone system
Surveillance camera system
Commissioned machine security system
Concurrent use of intrusion-alarm systems
Concurrent use of emergency warning systems
Concurrent use of surveillance camera systems
Concurrent use of interphone systems
Concurrent use commissioned machine security systems
Entrance control system
Surveillance camera system
Shoplifting prevention system
Surveillance camera system
Surveillance camera system
Vehicle burglar-alarm system
Bag snatcher and thief alarm system
Molester/ruffian repulse buzzer, etc
Policeman's club, spark shock generator, etc.
Anti-bullet/anti-sword jackets, anti-bullet shield, anti-bullet
helmet, etc
Vehicle paint-spray device, wiretapping detection equipment,
metal detector, etc
Figure 1-2. Classification of Crime Prevention Facilities and Equipment
1-3.
How television works
A camera is analogous to the human eye and light passing through its lens is changed
into an electric signal by means of a charge-coupled device (CCD) or other image sensors
that correspond to the eye’s retina. The electric signal is output to a monitor via electrical
circuitry.
Monitor
Camera
Subject
Video signal
(Light)
Lens
CCD
Current-to-light conversion
Photoelectric conversion
Figure 1-3. The principle of Television Operation
2
The monitor’s image is made up of small black and white or Red, Green and Blue dots
(or pixels) similar to those that can be seen when a newspaper photo is enlarged. Like
these small printed dots, the smallest element the monitor uses to configure an image is
called a pixel. In newspaper photos, the size of the dot varies to create light and shade, but
in television, the size of each dot remains the same, with shades of lighter and darker dots
arranged accordingly. The greater the number of image pixels, the more finely on-screen
details can be clearly seen and a high-resolution image can thus be obtained.
Table 1-1. The number of pixels in the video medium
Medium
Number of pixels
Approximately 50,000 pixels
200,000 pixels
1,000,000 pixels
300,000 pixels
300,000 pixels
1,000,000 pixels
8mm video
16mm video
35mm video
Television (NTSC system)
Television (PAL system)
High-definition television (720P)
In a television system, pixel energy is converted into electric energy and transferred to
another location, where the converted electrical energy is further converted into light. This
process of converting light into electrical energy is referred to as “photoelectric conversion,”
while the reverse is referred to as “current to light transference.” It follows that cameras are
photoelectric conversion devices and monitors or televisions are current-to-light transference devices.
Regarding methods of conveyance, each pixel’s black and white brightness and darkness or color tone is converted into electrical signals in an orderly sequence, similar to
repeatedly reading text from left to right till the end of the page is reached.
The converted electrical signal is then transmitted to a television monitor which in turn
arranges each pixel in the same order and same positional relation and at the same time
reproduces each pixel’s black and white darkness as well as color tone from the electrical
signal to reconstruct the same image as the original. In other words, the image to be
transmitted is resolved in specified order and the pixels of the resolved image are reconstructed in the same order. This operation is called scanning and the operation of enabling
solution scanning at the camera in step with scanning reconstruction at the monitor is called
synchronization, while matching the timing, as just stated, is called synchronizing.
Because the human eye experiences an afterimage phenomenon, if one picture is
transmitted every 1/30-second (NTSC) or 1/25-second (PAL), the human eye perceives it
as a moving image. This single picture is referred to as a frame and its scanning method is
as noted above. In reality, however, the beam first scans lines 1, 3, 5 and when it reaches
3
the bottom of the picture area, a rapid retrace takes place. The beam then scans lines 2, 4,
6 until it reaches the bottom then repeats. Using this method, when transmitting 30 (NTSC)
or 25 (PAL) screen frames per second, it appears that two-times coarse 60 (NTSC) or 50
(PAL) field screens are transmitted. Therefore, 2 fields equal 1 picture frame image.
1
2
525'
3
1'
4
2'
5
3'
4'
5'
First scanning lines
Second scanning lines
Retrace
522
523
521'
524
522'
525
523'
524'
Figure 1-4. 2:1 Interlace (NTSC system)
This method is called “scanning line interlace”, in which the method of scanning exactly
the center of the space between two previous lines is called a 2:1 interlace and that of
scanning an arbitrary path between two previous lines is called random interlace. The 2:1
interlace is generally used in surveillance camera systems. The random interlace produces
screen flicker or deterioration of vertical resolution, but because of its simple circuit construction, it is sometimes used in small surveillance camera systems.
With the recent movement from analog to digital technologies, some televisions employ
the progressive scanning system, which features higher resolution and is used when reproducing pictures. In NTSC television, for instance, the progressive scanning system
scans all 525 lines in succession, instead of scanning odd-numbered and even-numbered
lines alternately like the interlace method, thus reducing flicker.
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1-4.
Television system
Unless the element that determines the television system is standardized, the compatibility between components that sense an image, transmit the signal and receive it cannot
be achieved. Each of the NTSC, PAL and SECAM systems is one of the world’s largest
television systems. The NTSC system is employed in such countries as the United States,
Canada, Japan, Korea and Taiwan. The countries that use the PAL system include western
European countries, China, Asian countries and Middle Eastern countries. The SECAM
system is employed in France, Russia and other eastern European countries, African
countries and parts of the Middle East.
Table 1-2. Standard of the World’s Three Largest Television Systems
No. of scanning lines
No. frames
Field frequency
Interlaced scanning
Vertical-to-Horizontal ratio
Video frequency band
Video frequency band
NTSC
525 lines
30 frames/sec
60Hz
2:1
3:4
4.2MHz
6MHz
PAL
625 lines
25 frames/sec
50Hz
2:1
3:4
5.5MHz
7MHz
SECAM
625 lines
25 frames/sec
50Hz
2:1
3:4
5.5MHz
8MHz
Further, the following video signal methods exist:
1) Composite video signal
Called VBS (Video and Color Burst signal) for color and VS (Video and Sync) for
monochrome, these signal method(s) are currently used for most video signals. It consists
of a luminance signal (Y), color signal (C), horizontal/vertical synchronizing signal (S) and
color synchronizing signal (B). However, the color signal and color-synchronizing signal are
not used for monochrome.
2) Y/C signal
This method transmits a luminance (Y) signal and a color (C) signal separately for higher
resolution.
3) RGB signal
In this signal, which is used in many industrial-use video projectors, the red (R) signal,
green (G) signal, blue (B) signal, horizontal synchronizing signal (H) and vertical synchronizing signal (V) are separated. Although a personal computer’s monitor output employs
this method, since the video frequency band differs depending on the type of equipment,
care is needed in setup.
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2.
CCTV System Design
2-1. Designing a CCTV system
System design may sound difficult, but what is important is “The aim of the system,” that
is, ”What a building owner requires of the system.” Making this aim concrete is the system
design. Dividing work into the following procedures will facilitate the system design.
1) Understand the intended aim of the system.
2) Study the installation locations of cameras and monitors.
3) Understand the environments where cameras and monitors will be installed.
4) Select cameras, lenses, and pan/tilt drives.
5) Select signal routing, monitors, and switchers.
6) Select recording methods.
Let’s proceed with the design by following these procedures.
2-2.
Aims of a surveillance camera system
The aim of the CCTV system is broadly classified into the following categories:
1) Security (Crime Prevention)
This application is generally referred to as “crime prevention cameras”. This aims not
only to create a psychological effect to act as a deterrent to crime, such as theft and molestation, but also to help identify criminals after crimes are perpetrated by reviewing recorded images resulting from the installation of a CCTV system. The system is used to
monitor conditions of facilities and places where people, material goods and money converge.
2) Safety (Disaster Prevention)
The CCTV system is also installed in facilities and places where accidents and disasters
are liable to occur. Its main aims include the prevention of accidents caused by natural or
man-made disasters, minimization of property loss and personal injury resulting from disasters. This permits understanding the situation immediately after the occurrence of accidents or disasters and examination of the cause of accidents after they occur.
3) Manpower Savings
The aim is to reduce manpower, expenses and time. The number of active security
guards can also be reduced in the above security and safety applications.
4) Customer Service
The CCTV system is used to improve service to customers. Examples of this include:
store owners monitoring and improving employees’ attitudes toward their customers, skiers
6
at ski resorts checking the congestion of the slope on the monitor installed in their hotels,
and waiters monitoring the timing for the delivery of the next course in a restaurant.
5) Other Applications
Other aims include applications such as: video conferencing, sale presentations and
distance learning educational television systems.
2-3.
System design elements
Based on the system’s intended purpose, examine the number of cameras, monitors and
their installation locations. System design should usually begin with clarification of the input
and output of an image and/or sound. In other words, the “Input device” implies cameras
and microphones, while “Output device” refers to monitors and speakers. Determining
these elements first, followed by components connected to such equipment, will permit the
system to be easily designed.
The range of areas or rooms to be monitored can to a certain extent be imagined without
actually visiting them, depending on the types of buildings or facilities the system is installed
in. Let us give you some concrete examples.
1) Convenience Stores
With the increase in the number of convenience stores where ATM’s and color copy
machines are installed, the number of crimes at these facilities has also increased. It is said
that convenience stores suffer much damage and loss resulting from shoplifting and employee theft. This is a situation that has stimulated demand for surveillance camera systems. The standard convenience store system consists of four fixed cameras, with dummy
(nonfunctional) cameras added in many cases if four cameras are insufficient.
The range of areas to be monitored: Inside the store and particularly blind spots hidden
from the sales counter.
Subjects: Products, suspicious customers and clerks’ attitudes toward customers.
Monitoring room: Office or home.
Monitoring person: Store manager or owner (who usually does not like a complicated
system operation).
2) Financial Institutions
The system not only acts as a deterrent to robbery, but also assists in police investigations by providing the police with video evidence. The number of cameras to be installed in
financial institutions largely differs depending on their size.
The range of area to be monitored: Places where cash is handled, teller windows, safes,
ATM areas, customer checkout line and back doors.
Subject: Robberies and suspicious customers, especially their faces.
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Monitoring room: Office and security guard room.
Monitoring person: Clerks and security guards.
3) Office Buildings
A great number of surveillance camera systems have been installed in public facilities
and large buildings in order to maintain safety by quickly detecting crime and taking appropriate actions.
The range of area to be monitored: Building entrances, emergency exits, public spaces and
rest room entrances.
Subject: Suspicious object left unattended and suspicious persons.
Monitoring room: Office and security guard room.
Monitoring person: Security guards.
4) Senior Citizen Centers and related facilities
With the rapid increase in the number of elder care facilities relative to the quick pace of
aging society, care facilities intended to accommodate Alzheimer’s and other patients have
also increased in number. Many facilities suffer shortages of workers to take care of these
elderly people. To compensate for this manpower shortage, some facilities have employed
surveillance camera systems to maintain the safety of those living and working in these
facilities. However, since many of these elderly people are long-term care patients, special
considerations must be given to the camera installation method in order to protect their
privacy. Because patients suffering senile dementia often loiter around outdoors without
any particular purpose, they need to be monitored by surveillance systems in which cameras are interlocked with sensors specially installed at building entrances and windows in
order to prevent accidents.
The range of area to be monitored: Corridor, lobby, entrance, visiting room and garden.
Subject: Facility occupants and suspicious persons.
Monitoring room: Office, security guard room and night watchman’s room.
Monitoring person: Nursing Staff and security guards.
5) Hospitals and Other Medical Facilities
Places to monitor include the lobby, waiting room and entrance. Taking into consideration the fact that some visitors dislike overt cameras, perform unobtrusive monitoring by
using dome type cameras.
6) Department Stores and Supermarkets
The surveillance camera system is installed as a means to prevent and detect shoplifting
as well as fraudulent insurance claims from staged accidents. Not only does the system
monitor the inside of the store, but it also acts as a deterrent to shoplifting by overtly
8
showing cameras to indicate that shoplifters are being watched. It permits all camera images of the inside of the store to be monitored from the office, thereby leading to smooth
customer flow and improvement of service. For example, by monitoring checkout or sales
areas, the number of checkout or sales clerks can be increased or reduced depending on
the checkout processing time.
It is also possible to monitor sales areas or parking lots from the security guard room. By
installing a surveillance camera system, security guard workloads are reduced, leading to
possible staff cutbacks, which can in turn eventually reduce expenses.
7) Hotels
Installing the system at the entrance, hall, lobby, elevator or parking lot can help prevent
troubles with guests. Dome-type covert cameras are used in hotels as well. One application
is to install cameras in the banquet hall to monitor from the kitchen to check the timing for
serving meal courses. In wedding ceremonies, high-quality 3-CCD cameras are used to
relay video images of the ceremony to the outside or record them on a videocassette or
DVD system.
8) Factories
Specially designed industrial-use camera systems are used for product inspection, but
normal camera systems are used to monitor work progress. The aims of these systems are
to analyze work processes for higher productivity or to monitor dangerous locations to
document accidents. In particular, surveillance cameras are installed in clean rooms or
other locations that workers cannot easily access, so that the work operating conditions or
instruments are monitored. Since specially designed camera housings may be required in
factories for protection of the camera against dust, heat or chemicals, care is needed when
designing the factory systems.
9) Transportation
At train stations, surveillance systems are installed to monitor arriving and departing
trains in order to prevent accidents on the platform. The systems are also used for transmitting information or providing guidance. For example, passengers in a station can view
monitors displaying the train arrival and departure information as transmitted from the
camera.
10) Other Applications
Many other applications and aims of camera surveillance include monitoring of dams (for
prevention of accidents when water is discharged) and traffic congestion.
The range of areas to be monitored should be carefully determined in consultation with
owners and architects, with the cameras installed in the locations finally selected.
9
2-4.
Conditions for equipment selection
As noted above, the CCTV system is basically comprised of the camera, monitor and
signal transmission path that connects the two. When selecting the camera, it is important
to consider performance that is appropriate for the intended application. Regarding camera
housings, it is important to select the most appropriate type depending on where each
camera is to be installed. Pan/tilt heads and lenses may also be required depending on the
mounting method or the monitoring range. In addition, accessories and remote controllers
for operating the camera movement from distant locations may be required. Table 2-1
shows conditions that must be determined for equipment selection.
Table 2-1. Conditions for Equipment Selection
Conditions to be
Determined
Subject or place
Contents to be examined
Equipment to be selected
Color and brightness
Color/monochrome camera and
high-sensitivity camera
Lens(wide-angle, standard and
zoom),number of cameras and motorized pan/tilt head
Dome camera, pinhole lens, etc.
Target and observa- Size of target and room
tion range
Camera’s external
View
Installation place
Mounting method
Synchronization
Method
Distance to camera
Shape of camera and installation
method
Temperature, humidity, dust and
rain
Wall, ceiling, and pole
System configuration unit power
frequency (50 or 60Hz) and wiring
method
Maximum cable length and
frequency bandwidth
Monitor screen size
Size of monitor room and aim of
surveillance
Monitor display
Number of cameras, sequential
Method
display and multi-segment
split-screen display
Number of monitors Number of cameras, size of monitor
room, number of places monitored
and aim of surveillance
Video recording
Aim of recording, media and time
System
interval
Instant response
Aim of surveillance
Capability
Equipment storage Storage form
10
Camera housing and outdoor box
Mounting hardware
Vertical gen-lock and drive unit
Cable compensator, relay box, media
converter, transmitting device and
LAN equipment
Monitor: CRT or LCD typically
Switcher, Multi-viewer and multiplexer
Video signal splitter, switcher,
Multi-viewer, multiplexer and Matrix
switcher
Time-lapse VCR, digital video recorder and video printer
Sensor and preset memory system
Monitor rack, cabinet rack
and mounting hardware
2-5.
Camera installation
1) Notes on camera installation positions and orientation.
This section describes precautions designers should bear in mind when installing cameras in one area.
(a) An ultra-wide angle lens is required regardless of the room size when monitoring a
whole room.
(b) The use of an ultra-wide lens makes a subject smaller.
(c) Two or more cameras are required to display a subject in a close-up and monitor a
whole room.
(d) If space does not permit multiple cameras to be installed, use pan/tilt heads or zoom
lenses.
(e) Avoid backlight conditions. (Be aware of windows facing east or west.) When necessary,
use cameras that provide backlight compensation such as the TOA Wide Dynamic Range
cameras.
(f) When planning a small system, a camera and monitor can be used to select the optimal
location for camera placement. There are methods of simulating the picture range to be
displayed on the monitor using a PC and the appropriate software such as the TOA CMS
software.
2) Installation environments
Following the determination of the camera installation location, take care to completely
understand the environment where the cameras are to be installed, then specifically select
the necessary equipment. First, select the camera, lens, housing, and motorized pan/tilt
head. Conditions that you should know are as shown in Table 2-2.
Table 2-2. Installation Environment Conditions that must be understood
Condition for Selection
Examination Item
Brightness
Cameras minimum subject illumination
Backlight phenomenon
Cameras backlight compensation
Temperature, rain, dust and explosive at- Camera housing function
mosphere
Lightning and electromagnetic wave
Cameras video output
Privacy
Camera shape, installation method and image
blocking capability
3) Brightness
The camera to be used also needs to be considered depending on the brightness of the
subject to be monitored. Monochrome cameras require brightness of at least 100 lux, while
color cameras require that of over 300 lux in terms of recommended subject illumination.
11
When wishing to monitor subjects in low light conditions, consider turning on lights or using
high-sensitivity or infrared ray cameras. To maintain visibility in smoky conditions, thermal
cameras other than the infrared ray cameras can also be used.
(a) High-sensitivity Camera
This camera achieves high sensitivity with minimum subject illumination (0.03lx) by
slowing down shutter speed and using signal accumulation. One drawback of this camera
is that the signal accumulation method causes a frame-by-frame image advance or lingering afterimage.
(b) Infrared Camera
This camera uses a CCD sensitive to light in the near-infrared region of the spectrum. In
surveillance applications, it may be used in conjunction with a near-infrared emitter to
enable nighttime surveillance even in pitch darkness. Note, however, that the video images
thus produced are monochrome and the range of observation may be limited depending on
the near infrared emitter capabilities.
(c) Thermal Camera
This camera uses a CCD sensitive to light in the far-infrared region of the spectrum. It
was originally developed for monitoring temperature distribution in medical and research
applications. In the past this type of camera was typically expensive and somewhat difficult
to handle, particularly due to its cooling components, newer versions that are easier to
handle and more economical have lately become commercially available.
4) Temperature and Humidity
(a) Temperature
The operating temperature range for cameras in general is 14°F to 122°F(-10°C to 50°C).
A protective housing will be required for any camera installed in a place where temperatures outside this range are anticipated. Two types of housing are available, one being a
simple housing only, the other housing outfitted with temperature-adjustment devices like
heaters and/or fans.
Cameras can be equipped to endure even higher temperatures if necessary, by outfitting
them with housings incorporating electronic coolers (for ambient temperatures up to 150°F
or 70°C) or water coolers (for ambient temperatures up to 212°F or 100°C).
Fig. 2-1 Camera Housing
12
(b) Humidity
The most hazardous condition affecting camera operation is the formation of dew resulting from rapid increases in relative humidity. Such dew condensation occurs when
moisture in the air condenses into water droplets on a solid surface. If this takes place inside the camera or lens, it can cause the metallic parts to rust or corrode, eventually leading
to malfunction or early failure of the camera. Consequently, it is necessary to house cameras within a sealed case.
5) Lightning
If a camera or its wiring is installed outdoors in a region frequently subject to lightning
strikes, steps must be taken to protect the equipment from lightning damage. Protection
from direct lightning strikes generally requires large-scale measures like lightning rods,
without which it is difficult to counter the risk of damage. However, it is possible to protect
the equipment from the lesser hazard of lightning striking the ground in the vicinity by installing a video signal protector. A CCTV system generally requires three different types of
protectors, one each to protect the video signal, power supply, and control signal.
Coaxial cable (video signals)
Camera, etc.
Coaxial cable protector
Power supply protector
Grounding wire
Switcher or
other video
devices
Grounding wire
(a) Protector installation locations
(b) Coaxial cable protector
Fig. 2-2 Protectors
6) Electromagnetic Waves
If cameras are installed under high-voltage power lines or in the vicinity of a broadcasting
station, noise may appear on the monitor due to induction. The high frequencies, such as
video signals, make it very difficult to eliminate such noise entirely, but some improvement
may be gained by using a video transformer. With coaxial-cable superimposition (sin-
13
gle-cable) type cameras, however, such a transformer must be of the DC passing type to
allow installation. Another convenient counter-measure is to equip the camera with a
grounding wire.
7) Radiation
Because most of the CCD elements used in cameras are vulnerable to radiation, cameras installed in nuclear power plants are usually based on image-pickup tubes or incorporate special radiation-resistant CCD’s. In medical radiology labs, CCD cameras can be
used because the intensity of the radiation is lower than in nuclear power plants, but they
are still affected over time and must be replaced at regular intervals. In x-ray photography
rooms and cobalt treatment rooms, the surface of the camera lens typically discolors brown
over time, blurring the video image, and the camera image itself is affected by white spots
that eventually expand to fill the whole screen. Therefore, such cameras are usually installed within a protective housing, the front glass of which is regarded as a consumable
part to be replaced as needed.
8) Corrosion
Protecting cameras against corrosive environments is very difficult. The required
measures, such as coating or sealed construction, can be very expensive. If surveillance is
required in corrosive environments, the only possible protective measure is to minimize
corrosion by choosing the best (minimum exposure) installation placement.
In locations near the seashore, salt-carrying sea breezes are likely to corrode metallic parts.
In swimming pool facilities the culprit is likely to be chlorine vapor rising from the pool water.
Cameras are also vulnerable to corrosive gases including ammonia, hydrochloric acid,
sulfur dioxide, hydrogen sulfide, chlorine, fluorine and carbon disulfide. Particular care may
be required in factories handling or processing paper pulp, fertilizers, non-ferrous metals,
soda, sulfuric acid and synthetic fibers.
9) Explosion-Proof Areas
In operations like petrochemical plants and tunnel-excavation sites where flammable
liquids are handled or there is a strong danger of flammable gas leakage, strict regulations
are applied to all installed equipment and electrical works. When installing surveillance
camera systems in such places, it is absolutely necessary to select camera models with
appropriate specifications meeting local legal and regulatory requirements, for example
those with explosion-proof housings.
10) Rain and Dust
The rainproof outdoor housings are used wherever cameras might be exposed to precipitation such as: where water sprinklers are used for cleaning, or where considerable
14
exposure to water droplets is likely (e.g. swimming pools). Similarly, dustproof indoor
housings are used in dusty indoor locations, not only for the camera, but also to protect
relay boxes and other peripheral equipment.
Depending on ambient temperature and humidity, the front glass panel of the camera
casing can become clouded by condensation or frost. Defrosters are available to handle
such conditions. Similarly, wipers may be used for surveillance in the rain. Both defrosters
and wipers may be turned on and off by the remote controller as needed.
Camera housings manufactured in compliance with IEC (International Electro technical
Commission) standards bear “IP” grades used mainly to rate types of boxes. Table 2-3
below describes IEC529 Protection Grades.
Table 2-3 IEC 529 Protection Grades
IP–O∆
O: First characteristic : Protection against interference by the human body
and foreign objects
∆: Second characteristic — Protection against water entry
First
Characteristic
0
1
2
3
4
5
6
Second
Characteristic
0
1
2
3
4
5
6
7
8
Contents
No protection provided.
Fingers cannot touch charged internal components. (Diameter: 50mm)
Fingertips cannot touch charged internal components. (Diameter: 12mm)
Solid objects like tools and wires exceeding 2.5mm in diameter or thickness
cannot enter the unit.
Solid objects like tools and wires exceeding 1.0mm in diameter or thickness
cannot enter the unit.
Designed to prevent the entry of dust particles (to a degree that operation is
not adversely affected).
Dust particles do not enter the unit (to a degree that seals the unit completely
against dust particles).
Contents
No protection provided.
Not adversely affected by vertically descending water drops.
Not adversely affected by water drops arriving at angles less than 15° to the
perpendicular.
Not adversely affected by rain that falling at angles less than 60° to the
perpendicular.
Not adversely affected by water splashing from any direction.
Not adversely affected by direct water streams or jets from any direction.
Not adversely affected by strong, direct water streams or jets from any direction.
Water does not enter the unit even when it is completely submerged in water
to a specified pressure for a specified period of time.
Can be used constantly while submerged in water.
15
3.
Camera Selection
3-1. Types of cameras used in CCTV systems
1) Color and Monochrome Cameras
Color cameras can send images in color to the monitor screen. They are relatively more
expensive than monochrome cameras, but recently have come to be used in most CCTV
applications.
For surveillance applications in particular, it may be important to be able to recognize
clothing or vehicle color. Some color cameras come with an increased sensitivity function
that use image accumulation to deliver images of subjects in conditions with low illumination.
Monochrome cameras (also called “B&W” or black-and-white” cameras) are less expensive than color cameras. Generally they have lower minimum illumination requirements
compared to color cameras and therefore can produce clearer images of dark objects. They
also usually use single-plate type CCD’s, meaning they can produce images with higher
resolution than color cameras.
2) Camera Shapes
CCTV cameras are available in various shapes including cylindrical, box, dome and
combination dome types, each appropriate for specific applications and purposes.
(a) Cylindrical and Box Types
Either a cylindrical or a rectangular outer form can be selected depending on the size
and design of the installation space.
(b) Dome Type
The camera is covered with a dome that conceals it from casual view. Both the horizontal
(pan) and vertical (tilt) orientation of the camera can be adjusted. Most models come
equipped with a built-in 2X manual zoom lens.
(c) Combination Dome Types
Camera, motorized pan/tilt head and motorized zoom lens are integrated into a single
unit, operated by using a remote control. The camera case is sealed to provide excellent
protection against dust and moisture and helps to reduce noise (including the noise generated by camera rotation).
(a) Cylindrical
(b) Box Type
(c) Dome Type
Fig. 3-1 Camera Shapes
16
(d) Combination Dome Type
3-2.
Power supply systems
1) AC-Mains System
Power is supplied to the camera via the AC mains. Since the AC mains is also used to
power many other pieces of equipment besides the camera, it may be a lower-cost option
(depending on the conditions).
Monitor
Coaxial cable
Video signal
AC
Camera
Fig. 3-2 AC-Mains System
2) 24V AC System
Power is supplied to the camera via a 24V AC power supply, typically a 24V adapter or a
relay box. This system reduces the total cost when the camera is used in combination with
a housing and pan/tilt head.
Monitor
Coaxial cable
Video signal
AC power supply
AC 24V
Camera
Fig. 3-3 24V AC System
3) 12V DC System
Power is supplied to the camera via a 12V DC power supply. Since 12V DC power
supplies are usually used for sensor systems as well, cameras can be integrated with these
to achieve relatively inexpensive systems. One drawback of such power supplies is that
their direct-current power source does not allow them to be used for video signal synchronization and because of the voltage drop in long cable.
17
Monitor
Coaxial cable
Video signal
DC12V
Sensor system, etc
Camera
Fig. 3-4 12V DC System
4) Single-Cable (Superimposing) System
By superimposing the video signal and the power supply over the coaxial cable, with the
additional use of a camera drive unit, this system reduces the wiring between camera and
camera drive unit to a single cable. However, while it simplifies cable installation, it is not
suitable for use over long distances. Since the video signals superimposed on the power
supply differ from normal signals, the format cannot be used for units transmitting signals by
way of twisted-pair cables or for coaxial multiplex control systems. While most manufacturers offer single-cable systems, the superimposing method used tends to differ for each.
This means that TOA cameras and camera drive units cannot be used in conjunction with
those from other manufacturers.
Monitor
Coaxial cable
Camera power
Video signal
Camera drive unit
Video signal
Single-cable camera
Fig. 3-5 Single-Cable System
3-3.
Camera performance
The most important aspects of camera performance are its resolution and the minimum
subject illumination. “Resolution” is the quantitative measure of how clearly an image is
presented on the screen. It is measured both in horizontal resolution and vertical resolution.
Horizontal resolution is the maximum number of vertical black and white lines that can be
clearly distinguished by the eye when the image is displayed on a screen. The color cameras used in surveillance systems generally offer horizontal resolution between 330 and
480 lines. If higher resolution is required, three-CCD cameras with horizontal resolution
greater than 600 lines are recommended.
Vertical resolution is the maximum number of horizontal black and white lines that can be
18
seen in the reproduced image. Vertical resolution is constant and varies between 350 and
400 lines, depending on the scanning system. (NTSC, PAL or SECAM)
Fig. 3-6. Horizontal and Vertical resolution
“Minimum subject illumination” is the lowest intensity of illumination required for the
camera too barely catch an image of the subject. At this minimum level of illumination, the
subject cannot be clearly distinguished by the eye. The illumination permitting reproduced
image to be clearly visible is called “recommended subject illumination”. Illumination is a
measure of brightness and is measured in units called “lux” (lx). One lux (1 lx) is equivalent
to 1 lumen of light flux falling on a surface with an area of one square meter. It is generally
true that a brightness of 1 lx corresponds to the light of one candle viewed at a distance of
one meter. Fig. 3-7 shows guidelines for brightness.
Illumination (lux)
100,000
Outdoors, landscape
on a fine day (50,000-100,000)
50,000
10,000
5,000
Outdoors, shade on a fine day (10,000)
Outdoors, slightly cloudy (5,000)
1,000
500
100
Conference room, guest room
and in-store display (150-700)
Sickroom and hotel lobby (70-150)
50
Urban trunk road and emergency staircase (30-70)
10
Parking lot (5-30)
5
Seat in a theater and midnight sickroom (3-5)
1
Outdoor light in the park (1-3)
0.5
0.1
Full-moon night (0.1-0.3)
Fig. 3-7 Guidelines on Brightness
19
3-4.
Camera functions
TOA color cameras incorporate various advanced functions that allow them to operate
properly amidst various surrounding conditions. Models equipped with a DSP (digital signal
processing) circuitry ensure wide dynamic range and offer stable color and clear image
reproduction. The various camera functions offered are described below.
1) Backlight Compensation (BLC)
When a window or other bright light source enters the screen, the adjustment of
brightness to accommodate this bright area of the image may make the subject in front too
dark. For example, when observing an entrance door in security surveillance applications,
bright light entering from beyond the door may cause images of the faces of those entering
to be completely darkened. The BLC function can be used to display the image of the
subject at an appropriate brightness.
2) Wide Dynamic Range
The wide dynamic range cameras becoming increasingly popular recently are designed
to release their automatic electric shutters (AES) twice per frame, and then synthesize the
resulting two images so that both the dark and bright subjects are shown in a way more
easily visible.
While BLC cameras allow dark subjects to be seen clearly, wide dynamic range cameras
help ensure clearer reproduction of both the dark and bright subjects in an image.
CCD output
CCD output
High-speed shutter Low-speed shutter
(fixed)
(variable)
Time
Time
1/120 second 1/120 second
1/60 second
1/60 second
High-speed shutter output
Synthesized output
Low-speed shutter output
(a) Normal operation
(b) Wide dynamic operation
Fig. 3-8 Operation of Wide Dynamic Range (for NTSC)
3) Image Enhancer
The enhancer function adjusts and sharpens the contours of the subjects for clearer
image reproduction.
20
4) White Balance
The white balance function permits white objects to appear correctly within color image
reproductions. When this adjustment is made automatically it is referred to as "automatic
white balance" (AWB). Users can choose from two automatic white balance systems: an
automatic tracking type (ATW) system that continuously analyzes the image for white
balance adjustment during camera operation and AWB systems that adjust and correct
white balance when the power is turned on.
In a candle flame, the different colors in different parts of the flame correspond to different high temperatures; usually measured using a scale of units called “Kelvin” (K). When
a candle flame is observed through a surveillance camera, the white portions appear bluish
white while lower temperature portions appear yellowish red. This represents the white
balance corresponding to the temperatures of the light source, with color temperature for
the standard white being 6500 K. Similarly, we may sometimes notice that the colors of our
clothing we perceive indoors seem different when viewed outside in the daylight. Nevertheless, white always appears white to our eyes, regardless of the light source, because the
human eye is capable of adapting to light source color temperatures. Surveillance cameras,
in contrast, have less adaptability to color temperature and therefore reproduce colors
differently depending on the light source. It is for this reason that white balance is required
to adjust color tone without bias.
5) Automatic Gain Control (AGC)
This function adjusts video signals electronically in order to maintain a constant screen
brightness. When an input signal of intensity exceeding the predetermined level is received,
the gain is adjusted to prevent the signal from exceeding that level. Or, if the signal is too
weak, it is boosted to the preset level. Thus, AGC is an automatic gain adjustment function
for the purpose of keeping the signal intensity at a certain level. (Note: In the condition of
low light, AGC operation can result in picture noise.)
6) Automatic Sensitivity Adjustment (AES)
This function maintains the brightness of the screen at a certain level by changing the
shutter speed instead of relying on the aperture of the lens.
Note: AES cannot be used in areas where the power frequency is 50Hz, because the
shutter mechanism is already utilized by the Flicker Reduction function.
7) Flicker Reduction
In areas where the power frequency is 50 Hz, light from fluorescent or mercury arc lamps
may cause annoying screen flicker. This phenomenon is caused by a timing discrepancy
between the standard 1/60-second shutter speed of the surveillance camera and the
1/50-second-flicker cycle of such lamps. Setting the shutter speed at 1/120-second can
21
suppress these flickers, although it may also make the screen a little darker.
8) High-Sensitivity Accumulation Function
This function makes the shutter speed slower than normal to allow the camera to accumulate images over a longer period of time, thereby enabling color images of subjects to
be produced even in dark places. Enabling this function may cause noise, after-image or
frame loss on the screen. When the camera is in an extremely dark place, this function can
be used in conjunction with the Day & Night function described in the following subsection.
CCD output
Time
1/60 sec
1/60 sec
1/60 sec
1/60 sec
4/60 sec
Fig. 3-9 Operation of High Sensitivity Storing Function (NTSC system)
9) Day & Night Function
When the camera is used in a place darker than 1 lux, the Day & Night function and the
High-Sensitivity Accumulation function can be used together. To use the Day & Night
function under dark conditions, remove the infrared cutoff filter located in front of the CCD,
so that an infrared emitter is used as the light source for monitoring subjects.
Note: With this arrangement, even color cameras will generate monochrome images at
night.
Dummy glass
optical low-pass filter
Infrared filter
optical low-pass filter
CCTV
Lens
CCTV
Lens
CCD
Changing the filter allows infrared light
to reach the camera's imaging element at night.
(a) Daytime
(b) Nighttime
Fig. 3-10 Operation of the Day & Night Function
22
CCD
10) Privacy Masking Function
Taking privacy issues into consideration, up to four image subject positions can be
masked on the screen, so that places like the windows of apartment buildings that must not
be photographed can be exempted from surveillance.
Note: Privacy masking provides for camera movement tracking and scalability for zoom.
11) Other useful functions include:
(a) 2X Electronic Zooming
(b) Camera Title Display, which displays the name of the location under surveillance on
the current screen.
(c) Screen Reversing, which corrects inverted or reversed images.
3-5.
Synchronization methods
“Synchronization” refers to the timing with which video images are scanned. The timing
of scanning the screen from left to right is called "horizontal synchronization", while the
method of scanning from top to bottom is called "vertical synchronization." The frequency of
the horizontal synchronous signal is either 15.734 kHz (NTSC) or 15.625 kHz (PAL) and
that of the vertical synchronous signal is either 59.94 Hz (NTSC) or 50.00 Hz (PAL).
When using a switcher to select among multiple video signals, failure to synchronize
these signals correctly may cause annoying momentary disturbances of the screen with
each switch. There are three different types of camera synchronization: internal synchronization, external synchronization and line lock synchronization. The camera may be set to
use any of these methods.
1) Internal Synchronization
Scans the video signal using the timing of the synchronous signal generated by the
cameras built-in synchronous signal generating circuit. This method does not allow coordination with other cameras.
Camera 1
Switcher
Synchronous circuit
H
V
Video signal
Built-in oscillation generator
Camera 2
Fig. 3-11 Internal Synchronization Method
23
2) External Synchronization
Sends the camera the reference synchronous signal generated by an external synchronous signal-generating device. This method adjusts the scanning timing (synchronization) of each camera by supplying the same synchronous signal with identical timing.
There are two methods of external synchronization: vertical external synchronization and
gen-lock synchronization.
(a) Vertical External Synchronization
Vertical external synchronization superimposes a vertical synchronous signal on the
video signal. This method eliminates the necessity of additional cables for synchronization,
making it easier to achieve synchronization.
Camera 1
Vertical gen-lock
or drive unit Switcher
Synchronous circuit
H
V
Video signal
Vertical synchronous signal
Built-in oscillation circuit
Camera 2
Video signal
Vertical synchronous signal
Fig. 3-12 External Synchronization Method
(b)Gen-lock Synchronization
For Gen-Lock Synchronization, the camera’s gen-lock input is connected to signals from
other cameras to synchronize them. This kind of synchronization requires connection via
two coaxial cables.
Video signal distributor
Camera 1
Video signal
Switcher
Camera 2
Gen-lock input
Video signal
Fig. 3-13 Gen-Lock Synchronization
24
3) Line Lock Synchronization
This method adjusts the vertical synchronization by taking advantage of the fact that the
60 Hz frequency of the camera’s AC power supply (commercial power supply) is nearly
identical to the frequency of vertical synchronization. While this method permits easy
synchronization by using a power supply of the same phase, it cannot be used in areas
where the power frequency is 50 Hz instead of 60 Hz.
Camera 1
Switcher
Synchronous circuit
H
Video signal
V
Built-in
Oscillation circuit
Power
circuit
Video signal
Camera 2
AC-Mains/60Hz
Fig. 3-14 Line Lock Synchronization System
Note: Non-synchronous cameras can be used in a system that utilizes a “Digital Video
Signal Processor”. The DVSP performs “Time Base Correction” to the input signals with the
result that all the input signals become synchronized.
3-6.
Camera mounts
1) Mount
Cameras are usually mounted on walls or ceilings in indoor applications and on walls or
poles in outdoor applications. In normal surveillance systems they are usually installed 3 to
5 meters above the floor, making them difficult to reach but allowing relatively easy to access for inspection and service.
Camera mounts should be selected carefully based on the camera’s size and weight, as
well as its housing, taking into account weight limits and connector locations.
2) Motorized Pan/Tilt Head
Motorized pan/tilt heads are used to move cameras to provide wider coverage of the
area under surveillance. They can be rotated by remote control both horizontally and vertically. Horizontal rotation is called "Pan" and vertical rotation "Tilt."
“Auto-pan” allows the pan/tilt head to repeat the same panning pattern. Select the type of
pan/tilt heads with weight limit capacities appropriate to the camera and lens to be mounted.
There are both indoor and outdoor use types.
25
Lens Selection
4-1. Angle of view settings
The angular range covered by a camera is referred to as its “angle of view” and is determined by the focal length of the lens and the size of the imager (CCD) on which the
picture is formed.
Note: For multiple lenses with identical focal lengths, the angle of view will not match if
the size of the cameras CCD is different.
CCD image-sensing surface
Lens
Lens focal point
Size of screen
4.
Angle of view
Focal length
Fig. 4-1 Angle of View
CCD screen sizes are available in 1/4", 1/3", 1/2" and 2/3" types, measured based on it's
diagonal dimension. This difference in size makes almost no difference in terms of performance, but it does change the range of the view field.
Formulas for calculating field range
W
1/3" Type:
W = 4.8/f x L (m); H = 3.6/f x L (m)
1/4" Type:
W = 3.6/f x L (m); H = 2.7/f x L (m)
W: Width of subject
H: Height of subject
L: Distance between subject and camera
f: Lens focal length (mm)
H
L
Fig. 4-2 Types of Lens and View Field
The angle of view is expressed by the following formula:
θ = 2 tan -1(
l/2
)
f
θ :Angle of view
l : Effective dimension of CCD(mm)
f : Lens focal length(mm)
26
The angles of view for different lenses are listed in the specification sections of catalogs.
Generally these are as shown in Table 4-1.
Table 4-1. Angle of View
Type of lens
Standard lens
Wide angle lens
Super wide angle lens
4-2.
Angle of View (Horizontal)
30 – 40°
55 – 60°
Over 60°
Angle of View (Vertical)
20 – 30°
45 – 50°
Over 70°
Lens mount
The part connecting the lens to the camera is referred to as the “lens mount.” There are
three types of mounts: C mounts, CS mounts and bayonet mounts. If a lens mount type
does not match the camera requirement it will not be able to mount the lens to the camera
properly.
C mounts and CS mounts have the same thread pitch and diameter. The only difference
between the two is in the flange back (the distance from the mounting face to the CCD
image-sensing surface) which is 17.526 mm for C mounts and 12.5 mm for CS mounts.
Note: CS mounts are shorter than C mounts, but C mount lenses can be mounted on a
CS mount camera using an adapter.
As technological progress has made cameras increasingly smaller, CS mounts with their
shorter flange backs are becoming more popular. The bayonet mount is often used for
3-CCD type cameras and has no interchangeability with either C or CS mounts.
Fig. 4-3 Lens Mount
4-3.
Auto-iris lens
Cameras equipped with an “auto-iris” function automatically adjust the aperture (iris
opening) to match ambient brightness in order to maintain the brightness of the picture on
the screen at a certain level. Lenses with manual aperture adjustment and without auto-iris
are also available for use in windowless warehouses or other places where brightness does
not change over time.
27
The two types of automatic aperture lenses include the Video type and the DC type (to
be selected according to the camera specifications). The video type adjusts the aperture
opening based on the video signal (supplied to the lens) as it is analyzed within the lens
electronics. In the DC type, analysis is conducted by the camera microprocessor to send
the DC control voltage to the lens. These two types offer very similar performance, but the
DC type is less expensive .
If a camera uses a manual iris lens and is equipped with AES (a function that maintains a
constant screen brightness level by adjusting the shutter speed), then it picks up scenes the
same way as an auto-iris camera does. The AES function cannot be used in areas where
the power frequency is 50 Hz and fluorescent or mercury arc lamps are used as the light
source. In such cases the shutter function will already be in use for reducing flicker.
4-4.
Types of lenses
The following types of lenses are usually used for surveillance cameras:
1) Fixed Focus Lens
This type of lens offers a lineup of standard, wide-angle and super-wide-angle versions,
all with a fixed angle of view.
2) Varifocal Lens
A zoom lens that is manually adjusted is referred to as a “Varifocal” lens. Although this
type of lens cannot be remotely controlled, its focal length can be adjusted manually when
the camera is installed. This eliminates the need to select a specific lens, making it more
convenient and versatile than fixed focal lenses.
3) Motorized Zoom Lens
This zoom lens can vary its focal length to permit subjects to be displayed in close-up or
wide-angle. The focal length ratio between the telescopic end to the wide-angle end is
referred to as the “zoom ratio”. Any given zoom lens is generally described as a “##:1 (##x)
zoom lens” to express this ratio. The greater this ratio, the more range you have to change
the size of the image. The motorized zoom lens has a built-in motor for changing the focal
length and can be remotely controlled. Cameras with motorized zoom lenses are normally
used in combination with motorized pan/tilt heads, with their zooming and focusing (iris)
operations controlled via a remote control unit.
4) Aspherical Lens
The radius of the surface of this lens is not fixed, which has the advantage of minimizing
image distortion in peripheral areas of the lens. In addition, an aspherical lens can offer
images that are brighter relative to its size (that is, allows it to be a lens with a smaller aperture ratio).
28
5) Pin Hole Lens
This is a kind of fixed focal-length lens usually installed behind a wall or in a ceiling to
monitor the room through a small hole (with a recommended diameter of 3.5mm). Such
covert cameras are useful in situations where building occupants might feel uncomfortable
being monitored by a more obviously positioned camera.
Pin hole lens + Camera
Fig. 4-4 Pin Hole Lens Installation
6) Prism Lens
This also belongs to the fixed focal-length lens category and is installed in a ceiling with
only the prism portion exposed. This lens type can be used when it is preferable that the
camera be invisible to building occupants.
Prism lens + Camera
Fig. 4-5 Prism Lens Installation
29
4-5.
Lens selection
Selecting the proper lens type requires taking into consideration the location or position
in which the camera will be installed and simulating the coverage area to be picked up in the
camera image. Such simulations can be approximated roughly based on the field of view.
Several points to bear in mind when selecting the proper lens are summarized below:
1) Wide-angle lenses provide a wide coverage area but subjects picked up in their images
will be shown smaller.
2) Standard lenses show the subject larger but have a narrower coverage area.
3) To eliminate blind spots within the smaller the room, the wider the lens view angle
needs to be.
To pick up detailed images from the whole of a wide area, either use multiple cameras or
equip one or more cameras with pan/tilt heads and zoom lenses.
30
5.
Monitor Selection
5-1. Monitors
Most CCTV monitors are designed solely for industrial applications and therefore do not
include built-in TV tuners. Therefore, they cannot receive broadcast TV programs. When
selecting a monitor, consider the positional relationship of the monitor to its operator to
determine the proper size.
Monitor
A
90 K
B
Recommended monitoring area
Monitor Size
Distance A, m (Ft.)
Distance B, m (Ft.)
9-inch type
0.9(3.0)
2.1(6.9)
14-inch type
1.0(3.3)
3.3(10.8)
21-inch type
1.2(3.9)
5.0(16.4)
29-inch type
1.7(5.6)
6.0(19.7)
Fig. 5-1 Monitor Size & Recommended Monitoring Distance
If a 4-segment split-screen display is to be used, Distance B should be shortened slightly
since the images will be smaller. Smaller monitors such as 9-inch types are easy to install
and can be mounted in equipment racks, but they are not suitable for observing the finer
details of images displayed on the screen. If the size of a room does not permit a small
9-inch monitor to be installed in usably close proximity to the operator, a larger monitor
should be selected.
Liquid crystal display (LCD) CCTV monitors for commercial applications are becoming
increasingly available and more accessibly priced. Their remarkable features include
space-saving thinness, lower power consumption and freedom from the danger of image
burn-in. The advent of LCD monitors is also bringing solutions to problems that have
proved difficult to solve using conventional CRT monitors. For example problems involving
contrast, off angle viewing and display speed.
31
5-2.
Reduced image scale on monitors
When the camera picks up a subject, the range of the coverage area varies depending
on the lens selected. This is also true of the monitor and the size of the subject that can be
viewed on the screen will differ depending on the size of the monitor. The actual size of a
subject that can be displayed on a given screen can be calculated using the following
formulas:
Wm
Pickup range
Pickup range
Hco
Hco
Wco
Hm
Wco
Camera
Wm: Monitor screen width (cm)
Hm: Monitor screen height (cm)
Wmo: On-screen subject image width (cm)
Hmo: On-screen subject image height (cm)
L
L: Distance between camera and subject (cm)
Wco: Subject width (cm)
Hco: Subject height (cm)
(a) Pickup range and subject size
(b) Monitor screen size and subject size
Fig. 5-2 Reduced Image Scale on Monitors
Table 5-1 Monitor Screen Sizes
Monitor Size
Height (cm)
Width (cm)
9-inch type
12
16
14-inch type
21
28
17-inch type
26
34
20-inch type
29
39
21-inch type
32
42
29-inch type
40
54
Formula (example for 1/3 type camera)
Wmo =
f × Wm × Wco
4.8 × L × 0.9
Wmo: On-screen image width (cm)
f: Lens focal length (mm)
Wm: Monitor screen width (cm)
Wco: Subject width (cm)
L: Distance between camera and subject (cm)
0.9: Overscan of monitor (cm)
Hmo =
f × Hm × Hco
3.6 × L × 0.9
Hmo: On-screen image height (cm)
Hm: Monitor screen height (cm)
Hco: Subject height (cm)
32
Values 4.8 and 3.6 are both constants for a 1/3” type camera. The constants for 1/4", 1/2”
and 2/3” CCD types are as follows:
Table 5-2 Constants for Camera Types
CCD Size
Constant for Width
Constant for Height
1/4" Type
3.6
2.7
1/3” Type
4.8
3.6
1/2" Type
6.4
4.8
2/3” Type
8.8
6.6
<Example>: What will be the size of the image of a 170cm tall person when displayed on
a 9-inch monitor when picked up from 10 meters away using a 1/3” type camera equipped
with a 4mm focal length lens?
Hmo =
4(mm) × 12(cm) × 170(cm)
= 2.52(cm)
3.6 × 1000(cm) × 0.9
From the above calculation, it follows that the image of the person when displayed on the
monitor will be approximately 2.5 cm.
5-3.
Notes on monitor installation
Bear the following points in mind when installing monitors:
1) Installation Location
Determine where to install the monitor. Multiple operator rooms may be required depending on the intended purpose of the system. The number of required monitors is determined by the size of the room in which they are to be installed and the number of operators.
2) Monitor Installation Height
For around-the-clock surveillance applications, monitors should be positioned at a height
slightly below operator eye level. Consider the operators’ normal working styles as well.
According to some statistics, four is the maximum number of monitors an operator can view
effectively at one time. When multiple operators will view a single monitor, a large projector
may be used. In any case, be sure to at least determine the maximum number of monitors
that can be installed and the minimum number of monitors required for the system requirements.
3) Room Brightness (Lighting)
If the monitor is placed in a dark room, operators may suffer eye fatigue. On the other
hand, too bright a room exposed to the direct sunlight may negatively affect the view-ability
33
of the screen. Also, installing lighting equipment in close proximity to the monitor or installing lighting equipment with no directivity could result in annoying light reflections from
the monitor screen.
4) Ventilation
Since monitors generate heat, they need to be positioned to allow for heat to escape.
Overheating of the surveillance room in general should be prevented. Especially when
monitors are placed on the operation table or in monitor racks, it is recommended that they
be equipped with ventilating fans.
5) Power Supplies
Remember that a large surge of electric current flows into monitors when their power is
turned on. When designing a system employing many monitors, it is important to ensure
that the system has sufficient circuit breaker capacity, as well as delay circuits that can
stagger power input.
Power supply voltage should be kept stable whenever possible. If voltage fluctuations
cause image distortion on the monitor, it may be necessary to change the power supply
layout or use a voltage stabilizer.
6) Induction
When multiple CRT monitors are installed side by side or one on top of another, magnetic
fields may cause horizontal oscillation wave interference, possibly resulting in color variations or noise appearing on the screen. Placing a ferrous metal type plate between the CRT
monitors can neutralize the influence of these magnetic fields. When using large CRT
monitors side by side, mount them in a metal monitor rack.
7) Image Burn-In
If a CRT monitor continuously displays the same picture for a prolonged period of time
(about 6 to 12 months on average, consult the CRT manufacturer for model specific information and recommendations), image burn-in may occur. To avoid this, take care to
avoid continuously displaying the same image on the screen. In particular, bright images
are more likely to cause burn-in, shortening the CRT life span.
34
6.
Switcher Selection & Video Recording
As the number of camera's increases, the number of monitors also increases. Since
there is a limit to the number of screens a single operator can view at one time and because
space for monitor installation is also limited, the number of monitors can be reduced by
switching camera outputs in sequence on a single monitor or by using multi-segment
split-screen displays. Also, since operators cannot always view all screens, sensors
connected to time-lapse VCR’s or DVR’s may also be required to capture unviewed images for later playback if necessary.
6-1.
Sequential switcher
To view multiple camera outputs on a single monitor, switch the outputs displayed on the
monitor in sequence or display them together on a split screen. A manual switcher is designed to allow manual switching among camera's images. An automatic sequential
switcher switches the images at specified intervals.
When sequential switching is used, the screen can display only one camera output at a
time, meaning that other camera images cannot be viewed simultaneously. In this case,
important scenes could be missed or discovered too late. If, for example, 12 camera outputs are sequenced to display on a single monitor at 10 seconds intervals, the total amount
of time to display images from all twelve cameras is 120 seconds. Therefore, the greater
the numbers of cameras, the longer the sequence cycle interval. To prevent important
scenes from one camera output from being missed while another camera output is being
displayed, the switcher should be equipped to receive the sensor signal in the form of an
alarm that instantly and automatically switches the display to the relevant camera image.
Note that when switching among multiple cameras by means of the switcher, the cameras
must be synchronized (see section 3-5 Synchronization Methods).
If three cameras are sequenced, the monitor screen will be switched as shown in Fig. 6-1.
Image from
Image from
Image from
Camera 1
Camera 2
Camera 3
Sequence
Fig. 6-1 Sequential Switching
35
6-2.
Multi-viewer
A Multi-viewer has a split-screen display function that allows multiple camera images to
be viewed on a single monitor. Either a 4, 9 or 16 segment split-screen display is possible.
The larger the number of segments, the smaller each will be on the screen requiring use of
a larger monitor. A Multi-viewer can also be connected to a sensor to switch the screen to a
sensor-operated camera output.
Since the video signal is digitally processed, cameras need not be synchronized. Other
versatile Multi-viewer functions include a screen freeze function and a 2X-zoom function
that digitally magnifies part of the screen. Using a split-screen display, multiple camera
images can be viewed simultaneously.
1
3
2
4
1
2
3
4
5
6
7
8
9
(b) 9-segment split-screen display
(a) 4-segment split-screen display
Fig. 6-2 Multi-viewer
6-3.
Matrix switcher
For systems with multiple operator rooms, the “distributed method” was conventionally
used by CCTV systems to distribute camera images to sequential switchers installed in
each.
Monitor
Distributor
Camera 1
n cables
Switcher
Monitor
Camera n
n cables
Fig. 6-3 Distributed System
36
Switcher
Nowadays, however, to save cables for video signal transmission, a new Matrix Switcher
control method that switches images at a matrix section has replaced the conventional
method.
Monitor
Matrix Switcher
One cable
Camera 1
Remote control unit
Monitor
One cable
Camera n
Remote control unit
Fig. 6-4 Centralized System
The signal routing made possible by a Matrix Switcher can switch video signals manually
or automatically. It can also be used to remotely control the zoom lenses and pan/tilt heads
from remote control units installed in several locations. In systems employing a large
number of cameras, the centralized system has an economic advantage over a distributed
system.
6-4.
Multiplexer
Because Multiplexers include a frame recording function, they can be used in conjunction with a time lapse VCR or DVR to record 9 or 16 camera images on a single VCR or
DVR in quasi-moving picture formats. The following table shows the recording differences
between a Multiplexer and a sequential switcher.
Table 6-1 Frame Switcher Recording
Sequential Switcher
Records by switching images at
Recording
1 to 60 second intervals
Normal Mode
Reproduces images as reReproduction
corded, but necessary scenes
& Retrieval
may go unrecorded.
Records by switching cameras
Recording
at each frame, but frame loss
Time-Lapse
may occur.
Mode
Reproduction Time is identifiable. Check pic& Retrieval
ture frame by frame.
37
Multiplexer (9 channels)
Records by switching camera at
each frame
Selects camera to reproduce
quasi-moving pictures at 3.33
frames/sec.
Records by switching cameras
at each frame.
Select camera for reproduction.
Easy retrieval.
To record images from more than one camera, either prepare as many recorders as
there are cameras or connect one recorder to the sequential switcher or Multiplexer to
record images displayed on the switched or split screens. Keep in mind, using the switcher
or Multiplexer may involve the problems mentioned above, including missing recording of
important scenes (sequential switcher) and image size reduction (Multiplexer).
A Multiplexer allows multiple images to be recorded by switching them frame by frame.
Thirty frames (NTSC) or 25 frames (PAL) are transmitted per second from each camera,
with one camera output being assigned to one frame and recorded in the frame recording.
When reproducing images for playback, individual frames from the same camera output
are retrieved and compiled into quasi-moving picture formats. With this method, all camera
outputs are recorded and only those cameras required can be selected for reproduced
playback. Recorded images can be displayed in sequential order, as well as on 4-segment
or 9-segment split screens. Note that because this method has not been standardized, TOA
models are not compatible with frame-switchers by other manufacturers. Take this into
consideration when using a TOA multiplexer in combination with non-TOA time-lapse
VCR’s or DVR’s.
Video image of camera 3
Video image of camera 2
Video image of camera 1
Video image of camera 1
Video image of camera 2
Video recording signals
1
2
3
4
5
6
7
1
2
Still-frame video image
Camera 1
1
1
Still-frame video image
Camera 2
2
2
Camera 7
Fig. 6-5 Operation of Frame Recording (when 7 cameras are connected)
38
6-5.
Time-lapse VCR recordings
1) Recording
VCRs are used when:
(a) Recordings should be kept as potential evidence of crimes or accidents.
(b) An operator does not always attend monitors.
(c) Performing remote surveillance.
In remote surveillance applications, if it is difficult to transmit images from places like
elevators, then a VCR can be used to record surveillance images for reproduction only as
needed. Either of the following methods may be used for this function.
(d) The tape is set in a recorder and recording takes place until the end of the tape is
reached. The tape then automatically rewinds and is used again, overwriting the previous
recording.
(e) Several tapes are prepared and used in rotation. In one typical example, seven
120-minute tapes are used in 24-hour mode, with each being replaced by the next at 8:00
AM each morning throughout the week.
This approach preserves video images for up to one week, since that is how long it will take
until any given tape to come back into the cycle to be reused and overwritten.
Table 6-2. Recording Mode vs. Recording Interval
Time
Mode
Recording time
(T-120 is used)
02
06
18
24
48
72
96
120
168
240
360
480
720
960
2 hours
6 hours
18 hours
24 hours (1 day)
48 hours (2 days)
72 hours (3 days)
96 hours (4 days)
120 hours (5 days)
168 hours (1 week)
240 hours (10 days)
360 hours (15 days)
480 hours (20 days)
720 hours (1 month)
960 hours (40 days)
Recording
interval
(Second)
0.017
0.017
0.05
0.2
0.4
0.6
0.8
1.0
1.4
2.0
3.0
4.0
6.0
8.0
Voice
recording
Tape running
Continuous running
Possible
Continuous slow running
Impossible
Intermittent running
2) Searching for Specific Images
Inevitably it will be necessary to search for a particular segment of video recording for
later playback. The larger a system becomes, the larger the number of VCR’s and tapes will
also become. Tapes themselves can be organized and labeled for later use based on their
39
recording time and location, but it can be quite difficult to search within any given tape for a
specific event, especially if the event occurred over a short period of time. To facilitate such
searching, some VCR’s can record an alarm signal along with the video signal that sounds
during playback.
Recent advances in digital video compression technology have also made it possible to
record images onto media such as hard disks, DVD’s, or DV tapes as digital data. Since
these methods eliminate the need for cumbersome mechanical fast-forwarding and rewinding, searching is relatively easier than with conventional VCR recordings. It is also
possible to record such data along with sensor information, so that alarm-activated scenes
can be searched using a computer.
6-6.
Digital video recorders (DVR’s)
Digital video recorders (DVR’s) are classified into three types depending upon the recording media used. These include hard disk drive (HDD) types, optical disk (DVD) types
and combined DV cassette tape and HDD types. They can also be divided broadly into
multi-channel types equipped with frame-plexer functions and one-channel types not
equipped with such functions. Since digital video recordings also have their own life spans,
recorded data must be backed up. Unlike time-lapse VCR recording, digital video recording
uses compressed digital images offering the following advantages.
1) Easy searching
It is possible to locate and call up only those scenes tagged with alarm data, or to select
particular scenes by specifying there recording date and time. Both functions allow desired
scenes to be located more quickly and easily than was possible conventionally.
2) Simultaneous recording and playback
Video recording and playback can be performed simultaneously, a function that is not
possible with time-lapse VCR recording. Recording does not stop even during playback.
Using this function, images currently being recorded and reproduced can both be displayed
simultaneously using a multiple-segment-split screen.
3) High-quality video recording
In digital recording, the fact that the original signal does not deteriorate allows for higher
quality recordings. The deterioration of tape media and record/playback heads that are
normal with time-lapse VCR equipment do not occur, allowing higher quality images with
less variation in quality over time to be recorded.
4) Easy data handling
The digital nature of image data makes it easy to handle. Since every piece of information is recorded and stored as digital data, it can be input into a computer for editing or
transmitted easily over a LAN or other network.
40
7.
Sensor Type Selection
Camera surveillance systems are not always attended by operators keeping a constant
watch on the events displayed on the monitors. For this reason, they may be outfitted with
sensors to prevent important recorded scenes from being missed while operators are away,
or to allow the system to operate more efficiently when switching among multiple camera
outputs.
Sensor types include magnetic proximity switch types, shutter types, infrared types,
glass-break types, passive types and ultrasonic types. Table 7-1 outlines the features of
each of these.
Table 7-1 Sensor Types
Sensor Type
Magnetic
proximity
switch sensors
Shutter sensors
Infrared sensors
Glass break sensors
Passive sensors
Ultrasonic sensor
7-1.
Operation
Comprised of a permanent magnet and a magnetic reed switch. The
reed switch closes its contact when the permanent magnet is near and
opens its contact if the magnet’s magnetic field is removed. This sensor
is usually used to detect the opening or closing of windows and doors.
Used to detect the opening or closing of large doors, shutter sensors
include infrared, magnetic and mechanical types. The infrared type
consists of a light transmitter/receiver device and a reflective sheet that
returns the light sent out by the transmitter portion back toward the
receiver portion.
Comprised of unit that transmits a beam of near-infrared light and a unit
that receives that light. If the infrared light between the two units is cut
off, the sensor detects this interruption and outputs a signal.
Detects cutting or breakage of glass by an intruder. Vibration types are
attached directly to the window glass, while sound types are mounted to
a nearby wall or ceiling.
Passive sensors detect changes in far-infrared rays when a human
being or animal moves within the sensing area.
Ultrasonic sound waves are transmitted and reflected from moving
objects the speed of which alters the frequency of the returning sound
waves. The receiving equipment sends an alert signal when such frequency variations are detected.
Infrared sensors
An infrared sensor is comprised of a light transmitter and a light receiver. When the near
infrared light beam from the transmitter is interrupted by the passing of an intruder, a relay
contact closes causing the sensor to send an alert signal.
The properties of the near-infrared light used in such systems are close to those of light
in the visible spectrum, meaning that they can incorporate most types of optical equipment
without any modification. Near-infrared light also causes a strong photoelectric effect on the
receiving unit and it is therefore easy to work with.
As beams of light travel through the air they gradually weaken, a phenomenon called
“attenuation.” Attenuation is caused by two different factors, “absorption” and “scattering.”
Absorption occurs when radiation energy is transformed into another kind of energy;
41
scattering occurs when the radiated light encounters small particles in the air that change
its direction of travel in small increments. Attenuation occurs in the air even when the air
does not contain dust or vapor. Near-infrared light, however, can travel longer distances
than visible light (depending on the specific wavelength) with less haze-caused attenuation
because its wavelength is longer than that of visible light.
An infrared sensor system is generally comprised of a light transmitter unit that transmits
a beam of infrared light and a receiving unit that receives the light and processes the resulting signal. These two units can be installed on the same surface (reflection type) or on
opposite surfaces (opposing type). Figure 7-1 shows the basic equipment configuration for
the opposing-type system.
Light-beam
transmitter unit
Optical system
( Light reception )
Optical system
( Light transmission )
Electrical system
Light-beam
receiver unit
Near infrared light
Pulsed infrared light beam
Electrical system
Power supply
Detection output
Power supply
Fig. 7-1. Equipment Configuration for an Opposing-Type Infrared Sensor System
Opposing-type infrared sensors are available in 20-, 40- and 60-meter versions, depending on the size of the area to be monitored. They can be installed between 80 and 100
centimeters from the floor surface. The space between light transmitter and receiver must
always be completely clear of any obstructions.
It is also important to ensure that the space between the light transmitter and receiver is not
directly exposed to strong light sources such as sunlight or headlights. The entry of the
strong light into the light axis of the equipment over an extended period could reduce its life
span.
Light-beam
transmitter unit
Light-beam
receiver unit
80-120cm
Indoor installation: Up to 120m
Outdoor installation: Up to 60m
(a) Distance between light transmitter and receiver
(b) Sensor installation height
Fig. 7-2. Infrared Sensor Installation Example
42
7-2.
Passive sensors
Passive sensors detect the presence of an intruder by sensing changes in ambient
temperature. Because such sensors are susceptible to wind, they are not appropriate for
outdoor applications.
All substances with a temperature higher than absolute zero radiate some amount of
infrared radiation. Far-infrared light cannot pass through the materials used in a building’s
walls, floors or windows. Although glass appears transparent, it does not allow infrared light
with wavelengths longer than 2µm to pass through it.
A passive sensor’s detector utilizes a current-collection effect generated when electric
charge induction resulting from slight temperature changes is caused by a condenser or
other dielectric unit receiving the infrared rays. The sensor collects an electric charge by
filtering those far-infrared rays between 7 and 14µm, which is the range of wavelengths
radiated by the human body. The detection area to be monitored (specific spots, planes or
three-dimensional areas) determines the layout and number of optical equipment pieces.
Factors such as mounting position and wall/ceiling height determine the detection area and
require the selection of an appropriate sensor.
An alarm zone (the range of the spread of the light) made up of a single optical system is
referred to as the “sensing zone.” If an intruder enters this sensing zone, the sensor’s detector picks up the far-infrared rays radiated from the intruder, causing the amount of
electric charge induced in the detector’s current collection unit to change. When this
change exceeds a predetermined level, the sensor outputs an alarm signal. The detector is
set to be most sensitive to speeds within 0.4 to 1 meter per second (1.5 – 4 kilometers per
hour), which is the usual speed range of intruders attempting to walk stealthily.
Fig. 7-3. Passive Sensors
7-3.
Motion detectors
Motion detectors react to any change in brightness within the detection zone set on the
monitor screen, without using external sensors. This type of sensor is particularly useful in
locations where it is difficult to install sensors or cables in the monitored location. One
drawback of this type of sensor, however, is that it often fails to function accurately and
cannot be used for many outdoor applications. Some multiplexer's come with a motion
detection function.
43
8. Remote-Controlled Surveillance and Network Cameras
8-1.
Remote-controlled surveillance
If the distance between a camera and a security room is over 3 kilometers (1.9 miles) or
if coaxial cables cannot be installed for some reason, then surveillance must be controlled
remotely. If it is difficult to install a coaxial cable, systems using laser, near infrared rays,
spread spectrum or mobile telephones might be considered. Care must be taken to secure
the power supplies of the equipment employed. Connection may also be achieved using a
LAN or lines furnished by Internet communication providers.
1) Laser
This method uses a laser beam to transmit a video signal over a distance to a receiver.
Since laser light offers excellent linearity, it can transmit signals over distances of 3 – 5
kilometers (1.9 – 3.1 miles), although it is necessary that there be no obstacles in between
and that the transmitter and receiver are fixed securely in place.
A laser system is not susceptible to rain or snow, but fog, birds or insects may interfere
with video transmission. Also, the laser-light generating device must be installed so as to
prevent the potentially damaging laser light from entering people’s eyes.
2) Near-infrared light
In this method, video signals are transmitted between a light transmitter and a light receiver by means of infrared light rays. Although this method is less costly than the laser
system, the transmission distance is much shorter at 300 – 800 meters (328 – 801 yards).
As with a laser system, signals cannot be transmitted past obstacles or if the transmitter
and receiver are not fixed securely in place.
An infrared system is not susceptible to rain or snow, but fog, birds or insects may interfere with video transmission. Infrared light is not dangerous to the eyes or other parts of
the human body, so the system can be installed even in locations where people might be
exposed to it.
3) Spread spectrum
Also called the “SS radio transmission method”, this system uses radio waves in the
2.4GHz ISM band to transmit video signals over distances 1 – 2 kilometers (0.62 – 1.124
miles). Although such video transmission cannot be performed if there are any obstacles in
between, the use of radio waves instead of visible or near-visible light means that the
transmitter and receiver do not need to be securely fixed in place.
4) Mobile telephone
Video signals are transmitted via dedicated equipment connected to a mobile telephone.
This system can be used everywhere provided the mobile telephone is within good recep-
44
tion range. The monitor at the other end also requires a telephone line. However, since
such images are compressed,* they may suffer frame loss or mosaic images depending on
transmission conditions. Further, since this method entails telephone fees, it is usually not
suitable for constant monitoring applications. There are also some countries in which mobile telephones cannot be used.
5) Telephone line
Video signals are transmitted using a dedicated transmitter device connected to a
telephone line. As with transmission by mobile telephone, the image data is compressed.*
6) Fiber optic cable
Fiber optic cables allow video signals to be transmitted over distances up to 3 kilometers
(1.86 miles), with the added advantage that the transmission path is not affected by external noise sources. Because video signals are transmitted “as is” (i.e. not compressed), a
relatively wide frequency band up to 50MHz may be permitted, which in turn requires a
quartz-clad cable (such as a GI cable). Fiber optic cables clad in ABS resin cannot be used.
*Video signal compression formats include the following:
(a)JPEG
Used to compress still-frame video image data at compression rates from 1/10 to
1/100.
(b) M-JPEG
Compresses moving picture data recorded on each frame using the JPEG method to
continuously record compressed data or reproduce decompressed data.
(c) H.261/263, MPEG
An image data compression method that achieves highly efficient compression by
eliminating and encoding time-related and space-related redundant portions of video data.
The general MPEG standard encompasses several specific formats including MPEG1,
MPEG2, and MPEG4.
8-2.
Network camera system
1) Network
Cameras may be connected to an existing data network to transmit video data over the
network’s lines or to control surveillance remotely using a personal computer connected to
those lines or accessing the network over the Internet. Monitoring video signals over
networks built on the already widely used Ethernet network standard is very likely to become one of the most popular options. Types of network include LAN’s (Ethernet including
10BASE, 100BASE and 1000BASE types, FDDI, ATM, etc.) and WAN’s (private lines, data
communication networks, wide area LAN services, VPN (Internet), etc.).
45
2) Equipment configuration
Equipment is connected directly to the LAN or other independent network to control or
monitor video images and/or speech audio. A network system can be combined with a
conventional system using: network cameras that connect directly to the network; a network video transmitter that can send composite analog signals over the network and a
network video receiver that can receive analog signals and convert them to composite
analog signals.
Network video receiver
(decompression)
Network camera
LAN cable
AC camera
Coaxial cable
LAN
Monitor
Coaxial cable
PC
Network video transmitter
(compression)
Fig. 8-1. Network Camera System
A network camera system compresses images and can transmit and receive that compressed data over the LAN or other network using protocols like TCP/IP. Advantages of the
network camera system include easy camera expansion and movement, image viewing
using a PC and the ability to control cameras remotely. It is also possible to incorporate a
data router into the system to monitor remote locations over ISDN or Internet lines.
Data compression methods generally used include JPEG, M-JPEG, H.261/263, MPEG-2
and MPEG-4. However, since these are usually incompatible with one another, be sure to
check the system’s data compression methods and PC viewer software carefully before
operating such a system.
When video surveillance is to share the LAN with other network systems (a company’s
PC network, for example), try to design the network with sufficient bandwidth that minimizes
the negative influence of the image data transmission, since the data involved tends to be
relatively heavy.
Also note that the limitations of the network itself may restrict the number of transmittable
image frames, picture quality and screen size.
When transmitting image data over the Internet, equip the system with a password
and/or encrypt the data to prevent unauthorized access.
46
9. Video Signal and Control Signal Transmission
9-1.
Coaxial cables
Coaxial cables with impedance of 75Ω are normally used for video signal transmission.
Coaxial cables are identified using following symbols:
RG - # # / U
RG: Radio Grade, High frequency cable classification symbol
#: Type number
U: Universal, General use
Table 9-1 High Frequency Cable (Example)
Cable outer diameter (mm)
Conductor diameter (AWG)
Characteristic impedance (Ω),
nominal value
Attenuation (dB/km), 10MHz
1)
RG-59/U
5.9
22
75
RG-6/U
6.8
18
75
29.5
23.6
RG-11/U
10.3
14
75
RG-15/U
13.8
14
75
11
13
Maximum coaxial cable lengths
Table 9-2 shows maximum video signal transmission distances. Signal transmission is
still possible even if the distance exceeds the indicated limits, but the longer the coaxial
cable length, the more resolution will deteriorate. Note: Even if the cable length does not
exceed the indicated limits, video signal transmission can still fail or be adversely affected if
it is subject to interference by AC power supplies or other electromagnetic field sources.
Use the guidelines in Table 9-2 to determine approximate usable cable lengths.
Table 9-2. Maximum video signal transmission distances (Example)
Coaxial cable type
RG-59/U
RG-6/U
RG-11/U
RG-15/U
Maximum cable distance,
m (yard)
250 (273)
500 (547)
600 (656)
750 (820)
Maximum cable distance, m (yard)
<When cable compensator is used.>
2,000 (2,187)
2,400 (2,625)
2,400 (2,625)
3,000 (3,281)
2) Cable compensator
Transmitting video signals over long distances may degrade image quality and make the
on-screen image appear out of focus, resulting in deteriorated resolution.
A cable compensator enhances the contours of subjects to compensate for such image
degradation, thereby allowing video signals to be transmitted over longer distances, as
shown in the right column of Table 9-2.
47
Monitor
Cable compensator
Coaxial cable
Video signal
AC
Camera
Fig. 9-1. Cable Compensator
9-2.
Twisted-pair cable transmission
In elevators or other locations where a coaxial cable would be difficult to install, a good
option is to change the impedance using a video transformer and transmit video signals
over a twisted-pair cable. A twisted-pair cable has the advantage of reducing the influence
of noise induced from external equipment. However, this method cannot be used for single-cable cameras.
(An example would be power over coax type.) →Camera looks like ACmain type that is
not our line-up.
Twisted-pair cable transmission unit transformer
Coaxial cable
Monitor
Twisted-pair transmission unit
AC
Coaxial cable
Twisted-pair cable
(maximum length of 1.2km)
Fig. 9-2. Twisted-pair Cable Transmission
9-3.
Control signal circuits
Signals used to control lenses or pan/tilt heads remotely are referred to as “control
signals”. Since many different types of signals need to be transmitted, depending on the
control target, it is best to use multi-core cables appropriate for each control target. Both
CPEV and CPEE cables are often used for such control signal transmission.
CPEV: Pair-type polyethylene insulated vinyl sheathed local cable
CPEE: Pair-type polyethylene insulated polyethylene sheathed local cable
48
Table 9-3. CPEV and CPEE cable characteristics
Performance Characteristic
CPEV
Chemical resistance
Excellent
Heat resistance
Good
Flame resistance
Good
Weather resistance
Good
Water resistance
Good
Flexibility
Good
Connection ease
Good
CPEE
Excellent
Excellent
Poor
Excellent
Excellent
Good
Normal
1) Short-distance control
A “direct control” system draws power directly from the remotely controlled unit. Over
longer distances, however, drops in voltage will gradually make such control impossible.
Pan/tilt head, etc.
Motor
Remote controller
Power supply
M
Switch
Figure 9-3. Direct Control System
2) Long-distance control
A “relay control” system performs control from a remote control unit via a relay box.
Pan/tilt head, etc.
Motor
Relay box
Power supply
Remote controller
M
Switch
Relay
Figure 9-4. Relay Control System
Maximum cable lengths will differ depending on the type of pan/tilt head used, but approximate lengths are as shown in Table 9-4.
49
Table 9-4. Remote Control vs. Maximum Cable Length (Example)
Maximum Cable Distance (m)
Cable diameter (mm)
Ø0.5
Ø0.65
Ø0.9
Direct control system Outdoor application
45
Indoor application
20
Relay control system Outdoor application
600
1000
1300
Indoor application
500
800
1300
Ø1.2
80
35
2300
2300
Ø1.6
140
60
-
Table 9-5 shows remote control targets.
Table 9-5. Remote Control Targets
Equipment
Control targets
Up
Down
Right
Left
Auto-pan
Telescope
Wide angle
Far
Near
Bright
Dark
Heater and fan
Wiper
Defroster
Power supply
Pan/tilt head
Zoom lens
Housing
Camera
3) RS-485 systems
RS-485 systems control the camera, zoom lens and/or housing using communications
based on the RS-485 standard. As shown in Figure 9-5, a pair of twisted-pair cables is used
as the control cable between a Combination Dome Camera and the Remote Controller,
facilitating cable installation.
50
Combination
Dome Cameras
1
Remote Controller
Multiplexer
Monitor
2
RS-485 cable
3
Coaxial cable
Termination
max.16
Figure 9-5. RS-485 Systems
9-4.
Electrical power construction requirements
Be sure to confirm the voltage and power capacity when specifying the electrical power
supply requirements. Note that the voltage of commercially supplied power may fluctuate in
some cases. Further, since a large surge of electric current generally flows when the power
to monitors is turned on, special care needs to be taken to ensure proper power capacity.
For systems using a large number of monitors, a circuit breaker capacity of three times the
rated power consumption is recommended, as is the use of an electrical power distributor
with a built-in delay circuit that supplies power to each monitor one after another instead of
all at once.
51
10.
Making Drawings
10-1. Preparing block diagrams
Once the basic needs and components of a system have been determined, the next
process is to reflect these in a block diagram. Points to bear in mind when creating a block
diagram are described below.
1) Organize equipment by installation location.
To make a block diagram as clear and easy to understand as possible, place pieces of
equipment that will exist in the same location as close to one another as possible and enclose them using a dashed line.
Security room
Monitor
Camera
Video signal
Drive unit
Fig. 10-1. Block diagram for equipment installed in the same location
2)
Create the drawing so that the signal flow moves from left to right and from top
to bottom.
Cameras and microphones should generally be placed on the left-hand side. Show
outputs using lines extending from the right of or below connected equipment and show
inputs using lines to the left of or above the equipment. If this makes the diagram difficult to
read, try using arrows instead of lines to indicate signal flow.
OO input
OO input
Equipment name
OO output
OO output
Fig. 10-2. method of the signal flow
52
3) Make the block diagram as detailed as possible.
Drawing a block diagram clarifies the signal flow and helps you to identify errors in your
design. Try to draw the block diagram to include details such as the confirmed input and
output specifications for each piece of equipment.
10-2. CCTV drawing symbols
Table 10-1. CCTV Drawing Symbols (Examples)
Name
Description
Symbol
Lens
Used on block diagrams and layout diagram.
TV camera
The lens side is to the left.
Camera body
Camera protection case
The window side is to the left
Ceiling
Ceiling suspension
TV camera direct
mounting method
Wall
Wall mounting
Erect mounting type
Motorized pan/tilt head
Ceiling suspension type
VDA: Video distribution amplifier
VDA
Signal equipment
PDA: Pulse distribution amplifier
Place an applicable symbol
within the rectangular.
Input
Switcher
The figure here shows a switcher
with a 4-IN/1-OUT configuration.
SW
Monitor
VCR
VCR
DVR
DVR
Operation device
SG: Sync signal generator
Output
RM
53
Appendix Unit Conversion Table
Meter
1
0.025399
0.304794
0.914383
1,609.31
Inch
39.3707
1
12
36
63,360
Foot
3.28089
0.08333
1
3
5,280
54
Yard
1.09363
0.027777
0.333333
1
1,760
Mile
0.000621
0.000015
0.000189
0.000568
1
Closed Circuit Television Systems
Fundamentals Course
TOA Corporation. TTI
04/01/2005
Edited 06/20/2005
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