Causes and solutions of video transmission interfe

2022-08-14
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Causes and solutions of video transmission interference in monitoring

in some specific areas of video transmission, there are electromagnetic radiation interference sources, which are characterized by diversification and quantification. As a result, we can't solve them in a single way in engineering construction, but we should analyze the interference sources according to different environments and completely solve the video transmission interference with the most economical and effective method

the phenomenon of video interference in serial number monitoring the causes of video interference in monitoring the methods to solve video interference in monitoring

1 the image is transmitted to the diagonal striped elevator, near the motor, the streamlined production workshop, the working environment of the power plant monitoring system, there are MHz harmonic and frequency doubling interference, and a certain range of yd-v/rf38 video transmission anti-interference device is used, and the video cable adopts shielded wire greater than 64 wires. (note for elevator use: tensile strength of video cable. There is a special self-supporting flat composite elevator monitoring cable on the market. This cable combines the video coaxial cable, power line, data line and steel strand into a flat ribbon cable, so that the tensile force of the whole cable is borne by the steel strand, and the tensile strength is very good, so that the signal cable will not be broken due to gravity during elevator operation)

2 image distortion (normal definition) the distance between the monitoring point and the monitoring center is relatively close, and the video signal amplitude is too strong, resulting in the overload of the monitor. Detect the video amplitude of the camera. Standard range: 1vpp-1.2vpp

3 the image has horizontal upward rolling ripple

in all video transmission technology fields, the monitoring system has the problem of unclean power filter and 50Hz low-frequency interference. Find out the interference source equipment by substitution method, And replace or repair

4 equipment. Under normal circumstances, the image cancellation society is progressing. Our technology can't be inferior to or produce very messy black-and-white bright band distorted signals. There are MHz harmonic and frequency doubling interference in the working environment of elevators, near motors, streamlined production workshops, and power plant monitoring systems. The amplitude is very strong, which exceeds the amplitude of video signals. Yd-v/rf38 video transmission anti-jamming device is adopted. Due to the strong interference signal, Note that the signal should be able to be watched normally before it is connected to the anti-interference transmitter. The video cable connected to the camera and the anti-interference transmitter should be high shielded or multi-layer shielded cable, which should be reliably connected. Ordinary video cable can be used for transmission. (note for elevator: tensile strength of video cable)

5 image jitter. When the frequency point of external signal interferes with the synchronous head in elevator, near motor, streamlined production workshop and power plant, the image will jitter

6 image gray color distortion (under normal conditions of the equipment) the distance between the monitoring point and the monitoring center is relatively far. The video signal amplitude (3) the preset number of experiments and the weak automatic shutdown cause the monitor overload, resulting in image distortion. Yd-v/rf38 video transmission anti-jamming device is used, and its RF output is 110dB, Syv-3 cable can transmit about 250 meters

7 the image background is not clean and there are snowflakes in the common cable monitoring system. The common cable transmission distance is far or the multi-level amplifier transmission design is improper. It must be ensured that the input level of the demodulator in the monitoring room reaches more than 65dB; In the amplifier input characteristics of multi-stage transmission, the higher the input level is required after the next stage (it must be debugged by a professional engineer)

8 two overlapping images or vertical bright lines run left or right (cross channel) in the common cable monitoring system

in the cable TV system, it is called intermodulation interference, which is caused by the large level difference between non adjacent channels. Test the level of channels in the whole line and adjust it to ± 3dB

9. The image has obvious twill lines. Should the sensor be checked in the common cable monitoring system? The general data obtained by measuring the sensor with the resistance block of the multimeter is: the input terminal is about 405; Output terminal 340 or so; The resistance value of the two leads at any one end and the other end is 280 series

in the cable TV system, it is called intermodulation interference, which is caused by the large level difference between adjacent channels. Test the level of the adjacent left and right channels, and adjust it to ± 3dB

10. The image character picture has bright edges (ghosting) to the left or right In the common cable monitoring system, the filtering unit in the modulator radiates signals from the input end to the output end for maintenance or replacement of equipment

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