GOST video surveillance. Development of CCTV systems

Chapter 16

DIGITAL APPLIED TELEVISION

Introduction. Based on the nature of the tasks they solve, television systems are divided into broadcast and applied. The latter, in turn, are divided into visual display systems, which reproduce the situation for the operator who does not make a quantitative assessment of the observed image, and measurement systems, with the help of which a quantitative analysis of the input signal is carried out.

Applied television systems are designed for transmitting and receiving images in industry, science, education, medicine, military affairs, security and other areas of human activity. The main difference between applied television systems and TV broadcasting systems is the limited number of information recipients. Therefore, in applied television there is no need for such strict standardization of scanning and signal parameters as in TV broadcasting.

Digital technologies in applied television are used primarily for compressing video and audio information for the purpose of transmission over narrowband communication channels and recording in memory and for image analysis in order to automate some system functions.

In particular, applied television systems are used in solving problems of automation of physical, biological, medical experiments, production and technological processes, astronomical observations, and in research natural resources and space. In this regard, the requirements for the accuracy and efficiency of television (TV) systems have increased.

Another important trend should be considered the universality of TV systems, i.e. the ability to solve various problems without significant restructuring of equipment by changing control and data processing algorithms. This trend is associated with the use of computers in television measuring systems (TVIS).

In this regard, there was a need to develop principles for constructing TVIS that ensure high accuracy and measurement efficiency various parameters and image characteristics; and there are also high demands on the quality of reproduction on a video control device.

Television systems for security of objects and surveillance production processes

As an example, consider a surveillance system developed by Intelligent Instruments Corporation, USA. The system provides monitoring of many zones located in different parts of the city, automatically selects the zone in which something is happening to show the operator and has other useful properties.

The system consists (Fig. 16.1) of a central station CS and many peripheral stations connected to the ISDN network through control and communication units (CUiSv). Each peripheral station contains a TV camera, an image encoder (video encoder), an audio input/output unit (audio I/O), an audio encoder/decoder (audio codec), and a memory. The central station contains an image decoder (Video Decoder), a monitor and the above audio channel blocks. BUiSv on the central station is performed on the basis of a PC, and on each substation - on the basis of microprocessors.

Rice. 16.1. Block diagram of the surveillance system.

During the observation process in each PS, the video signal is recorded in a memory that always contains the last few frames compressed using the JPEG method. Each new frame is compared with the stored previous one in order to detect changes that may be the result of movement in the observed area. When motion is detected, this MS establishes a connection with the CA via ISDN and begins to send a compressed moving image in real time.

The operator at the central station observes the resulting image on the monitor screen. It can also hear sounds and establish voice communication with people in the observed area. If necessary, the operator can cause the transfer of a stored high-quality still image (not in real time) from the PS.

Depending on the nature of the observed objects, the number of video cameras, and the operating conditions of the TV system, the structural diagrams for constructing a PS will also have their own characteristics.

Let's consider the two most typical options for constructing peripheral stations CCTV.

In Fig. 16.2, and the diagram of the TV security, surveillance and control system includes both a multiplexer and a DVR. From the outputs of the multiplexer, video signals are supplied to the video recorder, monitor, through a modem to the central station (control room) of the CA (Fig. 16.1), and alert to a sound or light warning device.

The second PS circuit of the CCTV system (16.2, b) includes a video recorder that combines the functions of a multiplexer and an image recorder on a hard disk, monitors, sound and light alarm, a computer for transmitting data to the network via a modem to the central station (Fig. 16.1).

Let's consider the purpose and operation of the most important devices TV surveillance systems.

Camera 1 9 alarm 4 relay 9 audio 1 audio Additional Main

inputs output inputs output monitor monitor

Rice. 16.2. Structural diagrams CCTV system PS.

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The scope of application of CCTV and the range of tasks solved with its help are quite wide. Television cameras have long become commonplace in supermarkets, offices and warehouses, not to mention such serious objects as banks, sensitive enterprises, etc.

CCTV systems consist of the following elements: television cameras; monitors; image processing equipment; VCRs or other devices for recording and storing video information; power supplies; cable network for information and power transmission.

Despite the fact that the world leaders in the production of CCTV equipment and systems, as they say, are on everyone's lips - Sony, Panasonic, Philips, Samsung, etc., it should be noted that CCTV is fundamentally different from household video equipment. Moreover, CCTV is a completely different product. And the differences here are not only external.

For example, monitors for CCTV systems differ from their everyday counterparts in higher resolution and reliability. VCRs used in security television have the ability to record more densely (from 24 to 960 hours of recording on a standard three-hour cassette), change the recording speed based on a signal from external devices. Equipment for image processing - quadrators, multiplexers, matrix switchers - are generally produced almost exclusively for CCTV systems.

What factors need to be considered when choosing CCTV equipment and systems?

First of all, you need to clearly define the tasks that the CCTV system will have to solve: the equipment will be installed on the street or indoors, what is the illumination of the object, how much information the system will have to perceive and process, in what mode it will have to work during the day and at night. Based on these parameters and requirements, a CCTV system is built.

When ensuring the security of objects, the main and main task for the security service is the preservation of material and other assets at the entrusted object.

Of all the technical means of security available today, only television video surveillance systems can immediately show the events currently taking place at a protected facility. A properly designed television video surveillance system allows you to instantly assess the situation in controlled areas in real time, reduce the reaction time to an emergency situation and ensure the adoption of the most appropriate measures to protect and counteract the circumstances that have arisen.

Currently, there are several main problems that can be solved using CCTV systems when protecting objects: general monitoring of the situation; detection of people, cars, animals, objects, etc. appearing in the field of view of television cameras; identification of detected images (monitored objects).

In addition, depending on the purpose, functions performed and complexity of the tasks being solved, CCTV systems can ensure the creation of various controlled zones at the facility:

CCTV zones, in which the operator, using one or two video monitors, carries out simple observation of the situation in various areas (fragments, etc.) of the object using several television cameras, switches and quadrators;
video control zones, video information from which is automatically (without operator participation) recorded on a special video recording device and can be reproduced for retrospective monitoring of the video situation at a protected facility;
video security zones, in which video surveillance and/or video control and automatic detection of an intruder or other phenomenon are carried out when the image ("picture") changes on the video monitor in the controlled area. In this case, an alarm is issued using internal and/or external sirens;
video protection zones, which are primarily equipped with multi-camera video surveillance, video monitoring and video security systems, controlled by multifunctional programmable matrix switches, multiplexers, computers and controllers with special facility security programs and included in an integrated facility security complex, which also contains various means burglar alarm, access control devices, several surveillance posts, security posts with immediate response personnel. At the same time, all the components of the complex are interconnected and make it possible, using multiplexers and computers, to rationally distribute alarm information (for example, turn on video surveillance with several television cameras from different angles upon an alarm signal, turn on additional lighting, etc.).

VIDEO SURVEILLANCE SYSTEMS

Video surveillance systems are divided into simple (one-two-camera) and complex, multi-camera, with various image processing.

Simple video surveillance systems are used for primitive, momentary monitoring of the situation at an object in real time.

If there are sufficiently serious requirements for monitoring a protected object in several zones, multi-camera video surveillance systems are used, equipped, for example, with several television cameras connected through switches, quadrators or multiplexers to one or two video monitors. In such cases, up to 8 television cameras are usually used, because a larger number of television cameras makes it difficult for one operator to monitor the situation in each video surveillance zone. Observation of 4 television cameras by one operator is considered optimal.

A simple video surveillance system consists of two elements: a television camera and a video monitor, connected by a communication line to transmit a signal from the camera to the video monitor. Such a video surveillance system is a basic element for video surveillance, video monitoring and video security systems of any complexity.

Video surveillance systems can be color or black and white (b/w). The vast majority use b/w video systems, because... They are much cheaper than color ones and have greater resolution. Color video systems are used when color carries significant additional information about the object of control (hair color, clothing, etc.) or, for example, about the color of protected cars.

The most important characteristic of a video system is its resolution, i.e. the ability to display the smallest details of an image. The usual resolution is considered to be 380-420 TV lines for a b/w camera and 300-350 TV lines for a color one. The video monitor should have a higher resolution so as not to degrade the overall resolution of the system. It is advisable to choose a video monitor for a video surveillance system with a resolution of 600-800 TV lines.

VIDEO CONTROL SYSTEMS

The most important quality of television video surveillance systems for the protection of objects is the ability to record and document over a long period of time video surveillance of events occurring at protected objects. To do this, use video recording on specialized video recorders or other recording devices, which can operate both in continuous mode and in frame-by-frame recording mode with a specified time interval between frames, with the obligatory recording of the current time and date. When playing such a recording, repeated retrospective monitoring of the entire situation in the observed zones, a detailed study of the alarming situation in the observed zone with the establishment of the time of events occurring, is possible.

Thus, video monitoring systems - these are video surveillance systems with video recording - provide great assistance to the security service in objectively assessing the situation at the site, identifying objects of control, and also allow assessing the quality of the work of operators.

VIDEO SECURITY SYSTEMS

As noted above, video security zones (video security alarm zones) can be created at protected sites in which an alarm signal is generated by the television system when the image coming from the television camera of the observed zone changes. For this purpose, the television system uses single and multi-channel motion detectors.

Motion detectors There are analog (usually single-channel) and digital (single- and multi-channel). In analog motion detectors (they are sometimes called activity detectors), separate marker windows can be highlighted on the video monitor with a white or black outline (usually rectangular), within which the movement of the intruder is detected by changing the image in them. To do this, in each marker window the average voltage of the video image signal is measured and separately stored and, then, after a given time interval, it is compared with the voltage in the same windows of the newly acquired image frame. If the difference in voltage is more than 10% (usual sensitivity threshold) in one direction or another, the motion detector generates an alarm signal.

In digital motion detectors, the image on the video monitor screen can be divided into several tens or hundreds of marker windows. Each marker window for motion detection can be programmed separately both in size and sensitivity. The sensitivity in this case is the number of mismatched elements and the amplitude of the mismatch in each individual element. Moreover, all marker windows can be configured in any combination at the request of the customer.

The image in each marker window of each frame of one video recording cycle is recorded separately in the memory of a digital motion detector and then, after a given time interval, is compared element by element (in accordance with the discreteness of the recorded image) with the image in the same marker windows of the newly received frame in the next cycle. An alarming situation arises if, when comparing two images in any identical marker windows of two frames, the number of non-matching image elements in one and/or several windows exceeds the specified one. In this case, the motion detector generates an alarm signal in the form of blinking frame of the marker window or other video signals on the video monitor screen, and also issues sound signal to internal and external sirens to attract the operator's attention. In most cases, at a controlled object at night and during the day, it is necessary to set a different set of detection parameters. Therefore, the detectors are set to two switchable operating modes: day and night, differing both in the configuration of marker windows and in sensitivity. Operating modes are switched using an internal or external timer.

BASIC ELEMENTS OF SECURITY TELEVISION SYSTEMS

TV cameras

All modern cameras for video surveillance systems are built using CCD matrices, the surface of which is a collection of light-sensitive cells (pixels), and the greater their number, the better the quality of the image being formed. The main parameter of a CCD matrix is ​​its format - its diagonal size, measured in inches.

Photo 1. TV camera

Video surveillance systems mainly use cameras with CCD matrix sizes of 1/4 and 1/3, 2/3 inches.

One of important parameters television camera is the resolution, which depends on the number of pixels on the CCD matrix and on the parameters of the electronic circuit of the television camera. The resolution of a television camera is measured in television lines. The higher the camera resolution, the better the resulting image.

Based on resolution, all television cameras are divided into two main types: regular resolution television cameras (380-420 TV lines) and high-definition video cameras (570-600 TV lines). Color television cameras have slightly worse resolution: 300-350 TV lines for regular resolution color cameras and 450-480 TV lines for high-definition color cameras.

Another important parameter of a video surveillance system camera is its sensitivity, which is usually understood as the minimum illumination at the object of observation, which allows one to distinguish the transition from black to white on the video control device (monitor). The sensitivity of television cameras is measured in lux.

Since the illumination on an object changes throughout the day, to maintain a constant level of light on the CCD matrix, television cameras with a built-in electronic shutter, equipped with a lens with automatic iris adjustment and other technical solutions are used.

The electronic shutter function of a television camera is similar to the shutter speed function of a camera, and its switching speed is usually 1/100000 of a second. Auto iris lenses are like the pupil of the human eye: the brighter the light, the more the aperture narrows, and vice versa.

The main element of any television camera for a video surveillance system is the lens, the most important characteristic of which is the focal length, measured in millimeters. The angle of view of the lens depends on the focal length in the following way: The shorter the focal length, the larger the field of view. Based on focal length, all lenses can be divided into two main types: short-focus and long-focus.

Typically, video surveillance systems use lenses with focal lengths from 2.8 mm (horizontal field of view angle of about 90°) to 12.0 mm (horizontal field of view angle of about 20°). As a rule, short-focus (wide-angle) lenses introduce nonlinear distortions into the image, especially noticeable at the edges. In timely video surveillance systems, the following main types of lenses are used as part of television cameras:

Lenses with a fixed aperture, which are used for indoor surveillance as part of television cameras equipped with an electronic shutter;
lenses with automatically adjustable aperture, used as part of outdoor television cameras operating in variable lighting conditions;
zoom lenses (vario lenses) - lenses with variable focal length, usually used as part of street television cameras placed on a rotary support device to control moving objects;
pin-hole lenses (eye of a needle) - a lens with an extended pupil. The diameter of the extended pupil is usually 0.8 to 2.0 mm. Such lenses are used as part of high-security internal television cameras for covert surveillance.

Hermetic casings

Hermetic housings are designed to operate in a wide range of climatic conditions and allow the use of various combinations of cameras and lenses. The casing is equipped with a sun visor (filter), a board for installing a camera, a thermostat and a patch panel. Some pressurized enclosures have additional equipment - fans, wipers, glass washers. It should be noted that imported heaters do not always meet our climatic conditions and are not always designed for severe frosts.

Photo 2. Hermetic casing

More stringent conditions for outdoor operation of video surveillance systems require their own constructive solution. Cameras used outdoors are placed in protective covers equipped with heating - pressurized housings (boxes).

Rotating devices

Rotating devices for video surveillance systems are designed for cameras with remote control. They provide rotation in horizontal (up to 365°) and vertical (up to 183°) planes or only in horizontal.

Photo 3. Rotating device

There are rotary devices with constant and adjustable angular speed of movement. Camera control signals are converted into specified mechanical movements using telemetric control signal receivers. As a rule, remote controls are supplied along with rotating devices to control lens zooms if necessary to obtain an enlarged image.

Infrared illumination devices

To ensure the operation of the camera in complete darkness, as well as for the secrecy of video surveillance, local IR illumination devices and IR spotlights are used to irradiate the observed object invisible to humans infrared rays.

Photo 4. Infrared illumination device

However, these devices also have some disadvantages: IR illumination devices cannot be used in conjunction with color cameras, and the power consumption of such devices is approximately an order of magnitude higher than when using conventional artificial lighting to create equivalent (for a CCD matrix) illumination of an object.

Monitors

As a video control device in video surveillance systems, specialized monitors are used, which differ from conventional televisions in their high reliability, much longer time between failures and increased resolution (about 800 TV lines).

Photo 5. Monitor

The choice of monitor size for a video surveillance system depends on the number of cameras, the images from which will be simultaneously displayed on the screen in multi-picture mode. For small video surveillance systems (about 4 cameras), it is reasonable to use monitors with a screen size of at least 12 inches diagonally. For multi-camera video surveillance systems (about 16 cameras), it is recommended to use monitors with a screen size of at least 20 inches.

In some cases, liquid crystal displays are used as video monitoring devices, characterized by low power consumption (common supply voltage 12 V), mobility of use and increased cost.

Specialized video recorders

To record video images in video surveillance systems, special video recorders are used, which differ from household models in the duration of recording on a standard video cassette E-180 (up to 960 hours), its high quality and the reliability of the devices themselves.

Photo 6. VCR

All special video recorders for video surveillance systems are equipped with so-called “alarm” inputs. When a signal from an “alarm” detector is received at the input of a special video recorder, it can automatically begin recording the ongoing event for a set time (from 0.5 minutes or more), and the video recorder automatically switches to a three-hour recording mode (continuous, in real time ).

Special video recorders can operate in two modes: continuous (recording time on a standard E-180 video cassette is 3 hours) and intermittent (recording time 24, 480 or 960 hours). In intermittent mode, frames are recorded with a certain discreteness (see Table 1).

Table 1. Frame recording resolution

When documenting video footage, a date-time generator should be used to record the current time of day and date. Important characteristics of a special video recorder are its resolution and reliability. The high resolution allows even small details to be captured, and reliability is important since these VCRs are designed to operate continuously for several years.

Video signal processing devices

To control multi-camera video surveillance systems and video image processing, the following main devices are used: video switches; real-time video quadrators; video multiplexers; matrix switches.

Photo 7. Video switcher

Video switchers for video surveillance systems are the simplest devices for controlling small video systems (usually up to 8 cameras). The switch allows you to display the image from any camera in the system on the monitor screen in manual or automatic mode. In automatic mode, the switching time is usually adjustable from 0.5 to 60 s. Most video switchers have "alarm" inputs for connecting external devices ( motion sensors, door position sensors, etc.), when triggered, an image from the television camera “responsible” for the area where the triggered sensor is located is displayed on the monitor screen. A special video recorder can be connected to the output of the video switch (Fig. 1a).

Photo 8. Switch operation diagram

Real-time video quadrators (or simply quadrators) are used in small video surveillance systems (up to 4 cameras) to simultaneously display images from all cameras on the monitor screen in real time in multi-picture mode, that is, each image occupies 1/4 of the screen. Almost all quads have the functions of a video switch, that is, at any time the operator can display the image from one of the cameras on the full screen. Most quadrators have "alarm" inputs. In each multi-picture window, you can set the camera number and display the current time (Fig. 1b).

Photo 9. Scheme of quadrator operation

Video multiplexers are designed to control the operation of a multi-camera system (up to 16 cameras), as well as to process video signals when recording on a special video recorder and playback. The video multiplexer has all the functions of a video switcher and video quadrator. In multi-image mode, the images from television cameras are discrete (“jerky”), and the discreteness increases with the number of connected cameras. This is due to the fact that the multiplexer digitally processes the video signal from each camera, losing some of the information.

Photo 10. Result of signal processing by a multiplexer

All video multiplexers have “alarm” inputs for connecting external devices (motion sensors, door position sensors, etc.). The multiplexer is usually connected to a main monitor (usually 20 inches diagonally), on which images from all television cameras are displayed, and an additional one, where the image from the television camera monitoring the most important area of ​​the protected object is usually displayed.

The main advantage of a video multiplexer is high-quality video recording from all cameras onto one video recorder, which is achieved by sequential frame-by-frame recording from all cameras without degrading resolution.

Most multiplexers have a built-in activity detector, through which you can select and set activity zones in the field of view of any television camera. When the video signal level changes in the established zone, the multiplexer will issue an alarm signal, according to which the image from the “alarming” television camera will be displayed on the monitor (usually additional), and will make a more detailed recording of the ongoing event on the video recorder (Fig. 1c).

Rice. 1st century Multiplexer operation diagram

There are the following main classes of multiplexers: simplex, duplex and triplex.

TO simplex multiplexer you can connect one video recorder to record images from all cameras around the clock, but in order to view previously recorded information, you will need to stop recording and only then start viewing. It is practically not used in modern systems.

TO duplex multiplexer You can connect two VCRs: one for 24/7 continuous recording and the other for playback. Moreover, playback can be carried out on an additional monitor, displaying an image recording on it either from one of the selected cameras, or in multi-picture mode.

Triplex multiplexer allows you to connect a monitor in addition to two VCRs to obtain a multi-screen image on it.

Matrix switcher- a device that allows you to build a flexible and easily customizable video surveillance system. The matrix switcher allows you to output the video signal from one of the connected cameras to any system monitor or VCR.

In addition, it allows you to program video output sequences for monitors and VCRs, as well as presets for PTZ and zoom units, with each camera having an individual output time for a specific monitor. Presets tell the zoom and pan-tilt units to perform a specific order of sequential actions (for example, rotate vertically 25 degrees up and enlarge the image 12 times, then rotate horizontally 50 degrees to the left).

Programming of the matrix switcher is carried out using the keyboard. Several remote keyboards can be connected to one matrix switcher, which allows you to organize several independent camera control channels. The matrix switcher has an RS-232 port for connecting to a computer, which allows you to program and control the actions of the switch using the latter. The matrix switch is equipped with “alarm” inputs for connecting security detectors or motion detectors, when triggered, you can set certain sequences of actions of the switch (for example, a camera located in the field of action of the triggered detector is turned on, its image is displayed on the main monitor and at the same time this information is recorded to a special video recorder).

Motion detectors

A video motion detector for a video surveillance system is an electronic unit that stores the current image from a television camera in memory and generates an alarm when changes occur in the protected area. Video motion detectors are used mainly in security systems for large objects, where the operator has to control a large number of cameras Motion detectors can be functionally included in multiplexers.

There are analogue and digital motion detectors. The simplest and cheapest are analog detectors, the action of which can, under certain assumptions, be compared with the action security detectors, connected to the alarm inputs of switches, quadrators, etc.

Digital video detectors movements are multi-channel devices that allow you to divide the protected area into separate blocks, each of which has its own response threshold: the higher it is, the greater the changes that should occur in the “picture”. Movement characteristics (start of movement, direction, speed, etc.) can be set programmatically, which makes it possible, for example, not to perceive a person moving in the direction of a protected object or parallel to it at some distance as an intruder. Setting up a system with digital detectors to the optimal mode should be done taking into account the specifics of the location where the camera is installed and the characteristics of the protected object (probable paths of movement of the intruder, the presence of vulnerabilities, etc.), otherwise it is difficult to avoid a large number of false alarms or, conversely, missing the intruder. Digital video motion detectors are used in complex high-end television systems.

Video transmission devices

To transmit a television signal, both wired communication channels (coaxial cables, telephone lines, fiber-optic lines) and wireless channels can be used: radio or infrared channel.

The most stable and high-quality operation of the system is possible when using coaxial cables. The maximum distance from the television camera to the video receiver depends on the type of cable used and for the best samples does not exceed 500 m.

To transmit signals over long distances, video amplifiers and modems (transmitters-modulators and receivers-demodulators) are used. In this case, the video signal is converted, stored, and transmitted using a modem using special equipment. The transmission time can range from a fraction of a second to a minute, depending on the requirements for the quality of the “picture”. Currently, the three most widely used systems for transmitting images over digital and conventional telephone lines are:

Video surveillance systems with image compression based on the “conditional update” (CR) principle, designed to transmit information solely about changes in the image from frame to frame;
systems with MPEG compression that use special algorithms for compressing images of moving objects;
systems with JPEG compression, providing independent compression of the image frame.

In special video surveillance systems, when increased noise immunity, information confidentiality and high resolution are required, fiber-optic communication lines are used. The range of such systems is practically unlimited. Their relative high cost is due to the fact that television cameras do not have an output for connecting a fiber-optic cable, which requires the introduction of electrical to optical signal converters and vice versa into the system. In addition, laying, splicing and connecting such lines is quite complex.

When creating mobile and portable video surveillance systems, as well as in cases where it is impossible or impractical to lay cable lines, radio communication channels are used. The transmission range ranges from several hundred meters to several kilometers. However, such systems have significant drawbacks: they can interfere with household television broadcasting, and the signal in the transmitter coverage area can be received by an attacker. Radio systems operating in the centimeter range do not have these disadvantages, as well as infrared systems. The latter do not require permission for use from the State Committee for Radio Frequencies of Russia, but they operate in a line-of-sight zone, and their range largely depends on the optical density of the environment (snow, rain, fog, dust, etc.).

VI. TELEVISION SECURITY SYSTEMS

Receive visual information about the situation at the protected facility or about the behavior and individual characteristics The intruder is only allowed to see a television image. The specificity of the tasks solved with the help of SOT makes them indispensable in some cases. Thus, television cameras and monitors demonstratively installed at the site can scare off potential criminals; covert surveillance allows the operator to visually monitor the situation at the site. Video recording allows you to obtain documentary material about ongoing events for subsequent analysis or as material evidence (identify the identity of the offender, determine the license plate number of the car, etc.). It is obvious that SOT can perform some functions of security systems (for example, detecting the fact of an intruder’s penetration into a protected facility). However, it is also obvious that the use of HFO in this capacity is extremely ineffective, both economically and technical points vision (an exception may be the protection of large territories and external perimeters, the equipment of which security systems either too expensive or technically infeasible).

To enhance the protection of facilities, it is necessary to use modern technical means of fire protection, the technical characteristics of which are subject to increased requirements.

13. SELECTION OF SECURITY TELEVISION TECHNICAL EQUIPMENT

Let's consider the main characteristics of SOT technical means that affect image quality, and the principles of their selection.

TV cameras

Main technical characteristics television cameras are: resolution, operating illumination range and signal-to-noise ratio.

The resolution of a television camera used in site security must be at least 450 television lines for both black and white and color television cameras. With this resolution, the calculation of other technical characteristics must be carried out taking into account the requirements for the need to detect, distinguish or identify (that is, the degree of recognition) of the target by the operator on the video monitor screen.

The relationship between the degree of target recognition and the size of its image on the video monitor screen is given in table 8.

Table 8 - The size of the target image on the video monitor screen and the degree of its recognition

The operating illumination range of a television camera should be wider (by about 10%) than the illumination range on the object (scene). If necessary, it is possible to organize emergency lighting of the object (areas of the object) at night to narrow the range of illumination. All television cameras installed outdoors must be equipped with auto-iris lenses for normal operation in a wide range of illumination (from 0.1 lux at night to 100,000 lux on a bright sunny day).

The signal-to-noise ratio of the television camera must be at least 50 dB.

All television cameras installed outdoors must operate at temperatures environment from minus 40 to plus 50 °C or placed in sealed thermal enclosures with a protection class of at least IP65.

Control and switching devices

To facilitate the work of the cell phone operator, it is necessary to use various control and switching devices: serial switches, quadrators, multiplexers, matrix switches. Recommended options for using control and switching devices depending on the number of cameras in the system are given in table 9.

Table 9 - Use of control and switching devices

The main technical characteristics of control and switching devices are: signal-to-noise ratio (at least 60 dB), input/output crosstalk (at least 45 dB), resolution (at least 600 television lines or 750 x 500 pixels).

Motion detectors

In a site where there should be no human movement, even for a certain period of time (for example at night), it is recommended to use motion detectors.

The motion detector used must:

Programmed to automatically transition the system at a certain time from the surveillance state to the security state;

Have several independently configurable detection zones;

Have audio duplication of alarm.

The main technical characteristics of motion detectors are: the minimum size of the detected target (at least 10% of the size of the detection zone), the minimum contrast of the detected target relative to the background (no more than 5%) and the range of target movement speeds (from 0.3 to 3.0 m/ With).

Video drives

To record the situation at a protected facility, it is recommended to use the following types of video storage devices:

Special video recorders of the S-VHS standard;

Digital recording devices (including those using hard drive computer) with a resolution of at least 400 television lines.

Recording time in in good condition system should not exceed 24 hours. When the system is in an alarm state, recording must be done in real time. It is possible to maintain only “alarm” recording, that is, recording with a video storage device only when notified of an alarm. It is recommended that for particularly important areas of the object, provide an operational rollback mode (that is, viewing previously recorded images) for 1 - 5 s. The signal-to-noise ratio must be at least 45 dB.

Video monitors

To monitor the situation at a protected facility, at least two video monitors must be used. For an operator to view a full-screen image from one television camera, it is recommended to use a monitor with a diagonal size of at least 14 inches, and for viewing a split-screen image - at least 17 inches.

The main technical characteristics of video monitors are:

Resolution - at least 800 television lines (for black and white images), 450 television lines (for color images);

Maximum image brightness. (Must be sufficient for normal visibility of the image under specific operating conditions);

Geometric and nonlinear image distortions - no more than 2% of the screen height.

14. FACILITY EQUIPMENT OPTIONS

When designing HFOs, special attention should be paid to compiling a list of premises and territories that need to be equipped technical means systems. It is recommended to include in this list:

The perimeter of the territory of the protected object;

Entry gate, checkpoint;

The territory of the facility directly in front of the main and service entrances;

Entrance doors of the main and service entrances to the building.

14.1. Perimeter of the facility territory

When protecting the perimeter of a facility using SOT, an exclusion zone (at least 2 m wide) must be designated along the fence, free from foreign objects, trees, bushes, tall grass and other obstacles. The entire perimeter is divided into straight sections and the dimensions (length) of the controlled zones are determined based on the required degree of target recognition. At each designated area, it is recommended to install two television cameras (at the beginning and end of the area), aimed at each other. This arrangement of television cameras allows us to avoid the formation of " dead" zones under each of the television cameras. Each television camera can be connected to a motion detector. This will automate the process of detecting an intruder. To work at night, it is necessary to provide emergency lighting along the perimeter or use infrared spotlights to illuminate the target (however, in this case it will be impossible to use color television cameras).

14.2. Entrance gate, checkpoint

The layout of the television camera for monitoring the entrance gates at the facility is shown in Figure 17.

Figure 17 - Layout of a television camera for monitoring entrance gates using SOT

The TK 1 television camera, aimed at the gate, has a viewing area slightly large sizes gate The installation location of the television camera is determined by its parameters. This camera can be connected to a vehicle license plate recognition system, which will automate the procedure for admitting vehicles to a protected facility. Just as when organizing perimeter security, for the operation of a television camera in the dark, it is necessary to have emergency lighting.

14.3. The territory of the facility in front of the main and service entrances

It is recommended to protect the area of ​​the facility in front of the main entrance with two television cameras (see. figure 18).

Figure 18 - Layout of television cameras at the main entrance to the building

The viewing areas TC 1 and TC 2 are selected and positioned in such a way that the particularly dangerous area in front of the facility (road, parking for official vehicles, etc.) and the front door of the main entrance are under surveillance. If there is a road in front of the building and there is a possibility of headlights vehicle into the camera lens, you must install it with the " white inversion"or with the ability to mask the directions of the scene from which illumination is possible, using a television camera.

14.4. Open areas

To protect open areas (for example, car parks), a television camera on a rotating (tilting) device and a lens with a zoom lens are used. An overview of the entire parking area is carried out with a minimum focal length lens. At the maximum focal length, it is possible to determine the license plate number of a car entering (leaving) a parking lot (from a parking lot). The camera can be connected to a vehicle license plate recognition system. The car parking security diagram is shown on Figure 19.

Figure 19 - Parking lot security scheme

When organizing video monitoring in parking lots, it should be taken into account that in the dark, a car enters the parking lot with the headlights on, against which the car’s license plate may become indistinguishable. There are two ways out of this situation:

At the entrance to the parking lot, use emergency lighting that compensates for the headlights;

Use a camera with the " white inversion".

15. SUPERVISION USING SECURITY TELEVISION SYSTEMS

There are two ways of conducting observation: open (demonstrative) and hidden. Both methods have their advantages and disadvantages and can be used to protect various buildings and premises, areas of the facility.

Open (demonstrative) observation

Open (demonstrative) surveillance is used to scare away a violator from committing an illegal act. Television cameras for open surveillance are installed mainly on the approaches to the protected object (for example, the perimeter of the territory, the area in front of the entrance to the object, etc.).

Television cameras used for open surveillance must:

Have high degree protection against unauthorized actions;

Be installed in special casings that protect television cameras from physical destruction;

Be rigidly fixed to the object’s structures (wall, pole, etc.) to exclude the possibility of changing the orientation of the camera;

Be located as high as possible (4 - 5 m) to prevent the intruder from influencing the television camera.

The wires connected to the camera (video, power, control) must be placed in a metal sleeve and rigidly secured to prevent them from being pulled out or broken. Cable distribution at the facility must be carried out in metal pipes.

Covert surveillance

Covert surveillance is used to secretly obtain images from a protected area of ​​an object. Television cameras used for covert surveillance are installed mainly on entrance doors premises. For this purpose, special miniature frameless and case-based cameras are used that are not protected from climatic influences. However, covert surveillance can also be organized on the street using television cameras, placing them in casings that are opaque to the eye, camouflaged, for example, as street lighting fixtures.

The installation of television cameras used for covert surveillance, as well as the wiring to them, must be done secretly.