TV supervisory system has distinct effect in modern building, the main reason that it can be used extensively is it can report of real time, figure, bona fide is monitored the picture of the object, it already became people to have surveillant pilot in modernization management a kind of very effective tool.
TV supervisory system by camera, transmit allocate, the processing of control, image and show 4 parts are comprised. This system is two-way multiplexing, want to transmit video signal to sink already, should convey to camera again control signal and power source.
1 control means reachs the transmission of control signal
The control function that TV supervisory system should have camera lens of stage, dynamoelectric to dynamoelectric cloud scorch, shield and power supply. The control means of the supervisory system of TV of how many decision that controls the distance between center and controlled center and controlled device.
(1) is become camera amount is little, when control distance does not exceed 500m, can use direct control means, transmit control signal with multicore cable. Amount of control line of this kind of fashion is much, construction amount is large.
(2) is become camera amount is little, control item is less, control distance is when 1000m less than, can use indirect control means. Amount of control line of this kind of fashion is more also.
(The 3) great progress as a result of PC technology, already used digital technology extensively at domain of traditional imitate TV monitoring now, this is means of control of data encode personal computer. This kind of means uses serial code to transmit control signal, systematic control line needs two only, apply to large and medium-sized systematic control and Sunday run are transmitted, still can use software general monitoring and call the police the system is compatible rise.
(4) is when control distance when 300 ～ 500m, the video signal that comes from camera and the control signal that come from controller end but common a coaxial cable, this is coaxial is inspected charge means. Although this kind of means can save control line, but this kind of equipment is at present costlier, integrated consideration wants when the design.
The allocation of 2 video signal and transmit
The allocation of 2.1 video signal
Do not exceed 5 when monitor and when nearby is installed, can use the bridge to receive minute of prescription form, see a picture 1; When all the way video signal should convey when the many monitor with further apart, should use video alloter means, see a picture 2.
The transmission of 2.2 video signal
Video signal transmission line has coaxial cable (lopsided cable) , balance symmetrical cable (phone cable) , cable. Balance symmetrical cable and cable are used at Sunday run to transmit commonly, use coaxial cable to transmit the transmission means of signal of video base band commonly to the building such as guesthouse hotel. Should use 75 - when 5 coaxial cable, general transmission distance is when 300m, lv of take an examination uses cable compensator. If use 75 - when 9 coaxial cable, the distance between camera and monitor can not add cable compensator in 500m less than.
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