RU2250506C1 - Transfer module for multichannel video surveillance system - Google Patents

Abstract

FIELD: video surveillance technologies.

SUBSTANCE: cable transmitter has serially connected modulator, which is meant for converting television low-frequency spectrum to radio-frequency, harmonics filter, high frequency amplifier and attenuator, and also power-feeding system filtering block, while output of cable transmitter is made with possible switching to input of ranges adding block of unified television main, formed by coaxial cable.

EFFECT: higher efficiency.

3 dwg

Description

The invention relates to devices (cable transmitters) for converting video and audio signals into a radio frequency television signal, “mixing” it into a cable coaxial line for viewing on television receivers, television tuners, computers or other television devices used in multi-channel video surveillance systems for round-the-clock protection of technical premises, entrances of residential buildings, landings adjacent to residential buildings of territories, parking lots, technical facilities comrades, cultural monuments, etc.

Known video surveillance systems containing a transmitting module transmitting a television signal through a telephone network (using a modem) or via a television channel (US, No. 4916737).

A device is known that is used in a multi-channel video surveillance system and provides adaptation (coordination on switching on and reproduction methods) of devices responsible for receiving, controlling, processing information from television surveillance systems with standard household recording and playback systems. The implementation of the interface device allows the television and audio surveillance system to provide the possibility of using it as a household monitoring and security system. A television signal from each of the surveillance cameras is fed to the interface device, which coordinates the inclusion, playback (recording) and selection of images from N cameras with a playback (TV) or recording (VCR) system. The selection unit provides matching of the selected channels using a control signal. Control block

provides coordinated inclusion of cameras and playback (recording) using a control signal. The implementation of the interface device provides the ability to use household television and video equipment in the surveillance system (RU No. 2129304, 1999).

The closest analogue is the system used as a security measure for closed residential and non-residential premises, open perimeters of warehouses, garages, administrative and industrial buildings, as well as video intercoms and the method implemented by it. This system enables the use of a coaxial wiring of a collective antenna for transmitting a television signal to the television sets of observation points without interfering with the signals of the television broadcasting stations. The system comprises television sets, cable distributors, a video surveillance unit, a television signal matching unit, a supply cable, an input cable amplifier, the video surveillance unit including a video camera, a microphone, a video signal converter, an amplifier, a modulator, a control filter, a controlled filter, a local oscillator, and a television signal matching unit includes a frequency-independent attenuator, an amplitude equalizer and a signal mixing unit (RU No. 2149460, 2000).

The closest analogue described above provides the creation of a television surveillance system using coaxial wiring of a collective antenna to transmit one television signal to two or more household TVs. The closest analogue is not intended to bring information to a single point of protection (control room) and does not provide the reception of video audio from several video cameras with microphones to one video surveillance unit.

The problem solved by the invention is to eliminate the disadvantages of the closest analogue.

The technical result achieved by using the invention is to provide real-time image and sound transmission from several video cameras with microphones through a single multi-channel system trunk (coaxial cable) to a security point (control room). At the same time, the proposed device, the transmitting module, provides the extension of the video surveillance system by transmitting up to 64 video signals synchronized with sound (coded PAL or black and white, a microphone with AGC and adjustable frequency response and sensitivity) via a single coaxial cable.

Unlike the closest analogue, the proposed technical solution allows the use of a single trunk formed by a coaxial cable for high-quality simultaneous transmission to a single control panel of signals from several video surveillance units located in different places.

The ability to transmit multiple high-frequency signals over a single coaxial cable is known in the art. However, attempts to transmit from several cameras at different distances from a single observation point, encountered a number of technical difficulties that did not allow to obtain high-quality signal transmission from several cameras to a single monitoring console. In particular, such difficulties include differences in the level of the summed signal and the group spectrum of television signals in the range addition unit (adder), the presence in the system of spurious emissions that interfere with television radio frequency signals that are higher in frequency than the television signal transmitted with which or video cameras, the mismatch of the wave impedance of the trunk and, as a result, the presence of crosstalk, reflections, attenuation and beats of other signals of the trunk. In the presence of a branched coaxial line, a rather complicated and time-consuming calculation of the voltage drop across different types of cable and different line lengths is required in order to ensure the feasibility and availability of the system.

The proposed transmitting module (cable transmitter) provides the possibility of increasing the volume of the video surveillance system by simply connecting additional modules to the existing trunk without investment in wired communications. This possibility is realized due to the fact that all information flows are carried out independently from each other with frequency separation in a single main coaxial cable, and power is supplied through a transmitting module from the central core of the coaxial cable of a single cable main.

Cable transmitter provides:

- the absence of a mismatch in the wave impedance of the trunk and, as a consequence, the absence of crosstalk, re-reflection, attenuation and beats of other signals of the trunk;

- lack of interference on higher-frequency television signals of the highway;

- the possibility of leveling the level with the group spectrum of television signals and, as a result, the normal operation of the subsequent equipment of the trunk (trunk television amplifiers, equalizers, dividers, taps, etc.);

- powering himself, a television camera (camcorder), etc. from arbitrary supply voltage in the trunk. There is no need for a laborious calculation of the voltage drop across different types of cable and different lengths of the trunk;

- normal transmission of signals (subcarrier frequencies) of reverse control in the trunk, that is, signals from the consumer to the sources.

The technical result is achieved due to the fact that the input of the transmitting module — a cable transmitter (trunk driver for converting a low-frequency video audio signal to a high-frequency modulated television signal) is configured to connect to the output of the corresponding video camera and microphone or low-frequency microphone amplifier, and the output of the cable transmitter is configured to connect to the input of the range addition unit, while the cable transmitter includes a filtration unit for the pit supply system made with the possibility of connecting to the central core of the coaxial cable through which the system is powered, and also includes a series-connected TV modulator, a harmonic filter (HPF), a high-frequency amplifier and an attenuator.

The TV modulator is designed to transfer the spectrum of the television low-frequency signal to the radio frequency of the TV signal (audio and video radiofrequency television signal), while a low-frequency television signal from the output of the video camera and a low-frequency signal from the output of the microphone amplifier, to the input of which the signal from the microphone is supplied, are input to the cable transmitter . The filtering block of the power supply system includes a block-blocking filtering block of television signals during the selection of the current supply, the blocking filtering block of feedback and control signals of the highway and a stabilizer, while the input of the filtering block of the power supply system is connected to the central residential highway through which the power is supplied from the system power source. The output of the filtering unit of the power supply system is connected to the power supply system of the camera, microphone, low-frequency microphone amplifier and high-frequency amplifier of the cable transmitter. The attenuator output of the cable transmitter is connected to the input of the range addition unit (adder) of the video surveillance system.

The invention is illustrated by drawings, which depict:

figure 1 is a schematic diagram of a television video audio security system for houses with a single control room;

figure 2 - transmitting module of a video surveillance system, including

video surveillance unit with a video camera and microphone;

figure 3 - input power from a power source.

A video surveillance system is a complex located on a serviced territory and built on a modular basis. All equipment is connected together by a single coaxial cable in an arbitrary configuration. All information exchange and power are also produced via a single coaxial cable.

The integrated high-frequency multi-channel video surveillance system contains video surveillance blocks with a video camera 1 and a microphone 2, a cable transmitter 6, which converts a low-frequency video audio signal into a high-frequency modulated television signal with a given carrier frequency, a television cable trunk 5 and a control panel 10 with a visualization and / or recording unit ( which can be used, for example, a computer).

The operation of the multi-channel video surveillance system consists in the fact that video surveillance of the state of a number of objects is carried out. The system contains the corresponding number of video surveillance blocks, each of which includes a video camera 1 and a microphone 2. The received low-frequency signal from each of the S video cameras 1 with a microphone 2 (or from a video camera 1 and a mic amplifier LF 3) is converted into a high-frequency modulated television signal. The received signal is introduced through the addition of bands 4 (adder) into a television cable line 5 formed by a coaxial cable, through which ultimately high-frequency television modulated signals are transmitted, each having its own carrier frequency. As one of the elements of the range addition unit 4, for example, a circulator, a directional coupler, and the like can be used. From the output of the range addition unit 4, which is built into the coaxial highway 5, high-frequency signals are fed to the input of the control panel 10, which includes a computer 7 or a television receiver equipped with an expansion card that allows you to receive and display images of several objects of observation simultaneously on the screen. Power supply of the system elements is carried out from a single power supply unit along the central core of the coaxial cable of line 5.

The system installed, for example, in a multi-access house (see figure 1), consisting, for example, of entrances and car parking, has several cameras 1 and microphones 2 (according to the number of monitoring objects). The output of each block of video surveillance (video camera and microphone) is connected to the input of the transmitting module - cable transmitter 6 (shaper trunk to convert the low-frequency signal from the cameras 1 with microphones 2 to a high-frequency modulated television signal).

Cable transmitter 6 — a signal conditioner for the trunk converts low-frequency video and audio signals coming from video camera 1 with microphone 2 into a high-frequency modulated television signal, that is, it generates a radio frequency (40 - 400 MHz) television signal and transmits it into one coaxial television cable (system trunk 5).

The cable transmitter 6 includes a power supply filtering unit, as well as a series-connected TV modulator 16, a harmonic filter (HPF) 17, a high-frequency amplifier 18 and an attenuator 19. The TV modulator 16 is designed to transfer the spectrum of a television low-frequency signal to the radio frequency of the TV signal ( audio and video radio frequency television signal), while the input of the cable transmitter 6 serves low-frequency television signal from the output of the camera 1 and the low-frequency signal from the output of the microphone amplifier 3, to the input to the signal from microphone 2 comes in low. The filtering unit of the power supply system includes a series-connected block 20 of barrage filtering of television signals during the selection of the current supply, block 21 of the barrage filtering of feedback and control signals of the line and the stabilizer 22, while the input of the filtering block of the power supply system (block 20 barrage filtering of television signals) is connected to the central residential highway, which receives power from the power source of the system. The output of the filtration unit of the power supply system (stabilizer 22) is connected to the power supply system of the video camera 1, microphone 2, microphone low frequency amplifier 3 and high frequency amplifier cable transmitter 18. The output of the cable transmitter attenuator 19 is connected to the input of the range addition unit (adder) 4.

The television cable line 5 is formed by a coaxial cable with connectors (or clamps) located at the joints of the sections of the line. The television signals from the outputs of the cable transmitters 6 are fed to the input of the range addition unit 4, at the output of which a complex video-audio signal is received from all video cameras with microphones located at the objects. The range addition unit 4 (adder) contains a power passage circuit bypassing the actual summation circuits, which is a direct current transmission unit 14 (inductor) and additionally contains a level regulator 15 at one input to equalize the levels of incoming and summed signals.

The resulting complex video signal is input to the control panel 10, which includes a computer 7 with a monitor (color or even white). The computer is equipped with a television (TV-) expansion board that demodulates the received television signals and splits low-frequency signals into S to simultaneously feed several images to the monitor screen.

The color RF computer monitor serves as a visualization unit. Information from one to S video cameras is displayed on the monitor (the number of “pictures” is determined by the operator’s ability to perceive visual information).

The monitor has video audio output to a tape recorder or an LF video capture card, it is also possible to work parallel with a computer, auto-switch with programmable flipping time of channels (a system for automatically switching channels of a TV used as an RF monitor).

The RF coaxial trunk switch for RF monitors allows receiving up to 512 RF video signals controlled from the serial port (RS-232) or from the input board of the RF video signals to a personal computer (RF multiplexer).

At the operator’s command (clicking the mouse button on the corresponding sector of the monitor screen), one of the channels is displayed on the monitor, that is, information from the selected video surveillance unit, and a full video audio signal is received and, along with viewing the “picture”, any sound environment can be heard from the microphone video cameras.

The power supply 12 is connected to the power supply system and through the filter 13 to the coaxial cable (line 5), which allows you to provide power to all components of the system. The filter 13 is designed to prevent the transmission of TV signals to the power supply and their attenuation, as well as to match the wave impedance with the line.

Thus, power is supplied to the central core of the coaxial cable. The power input from the power source can be structurally combined with a range addition unit 4 for decoupling the power supply of the line and entering the control panel 10.

Claims (1)

A cable transmitter comprising a modulator connected in series, which is designed to transfer the spectrum of a television low-frequency signal to a radio frequency, a harmonic filter, a high-frequency amplifier and an attenuator, as well as a filtering unit for the power supply system, while the output of the cable transmitter is configured to connect to the input of the range addition unit a single television line formed by a coaxial cable, the filtering unit of the power supply system includes serially connected the blocking filtering block of television signals during the selection of the supply current, the blocking blocking filtering of feedback signals and control of the highway and the stabilizer, the input of the filtering block of the power supply system is connected to the central core of the coaxial cable of a single television line, the unit for adding ranges of a single television line contains a bypass circuit the actual summation circuits, which is a DC transmission unit, to the output of the filtering unit of the power supply system The power supply system of the high-frequency amplifier is connected, and the attenuator output is connected to the input of the range addition unit of a single television line.

Images