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  • Video surveillance cameras interfere with the emergence of various solutions

        First, grainy interference

        This interference occurs, a slight normal image will not drown, but the image can not be serious, watch (or even destruction of sync). This phenomenon causes more faults are more complex. Generally, there are several reasons:

        1, poor quality video transmission lines, in particular, poor shielding (shielding is not a good quality copper network, or network is too thin and would not achieve shielding shielding effect). At the same time, this type of video cable wire resistance is too large, resulting in a greater attenuation of the signal is increased failure. In addition, such video is not a 75Ω characteristic impedance of the line and the parameters exceed the prescribed one of the reasons is the cause of the failure. As the above-mentioned interference is not necessarily bad is the video line generated fault, so the cause of the malfunction to be accurate and careful judgments. Only when rule out other possible only after the video cable from the negative point of view to consider. If the cable quality is really the best way of course all of this is to replace all the cable, and replaced to meet the requirements of the cable, which is the best way to solve the problem.

        2, due to the power supply system is not "clean" caused. Here, the power is not "clean" refers to the normal power supply (50 weeks of sine wave) superimposed on the interference signal. And this power of interference signals come from the grid using SCR equipment. In particular, high current, high voltage silicon devices, the pollution is very serious on the grid, which leads to the same power grid is not "clean." Such as the FM network in high-power thyristor control devices, thyristor rectifier, SCR AC-DC conversion device, etc., will power pollution. This solution is relatively simple, as long as the use of clean power for the entire system or on-line UPS power supply can basically be solved.

        3, the system is near a strong source of interference. This can be done to investigate and understand and be judged. If this is the reason, the solution is to enhance the camera´s screen, and the video cable to the ground processing pipeline.

        Second, deeper than the chaos of a large area textured interference

        Severe image has been completely destroyed, do not form images and sync signals, this failure is due to the video cable network wire and shielding circuit, open circuit caused. This happens more in BNC connectors or other types of video connectors. That this failure phenomenon occurs, the whole system often do not have the brightest signal problems, but only bad in those joints on large ones. Carefully examine these one by one as long as the joints, can be resolved.

        Third, a number of equally spaced bars interference

        Interference signal frequency is basically an integer multiple of line frequency, which is due to the video transmission line characteristic impedance is not 75Ω impedance mismatch caused by caused. Can also be said that this interference is generated by the video cable´s characteristic impedance and the distribution parameters do not meet the requirements of integrated caused. The solution generally rely on "beginning of the series resistor" or "terminal and the resistor" approach to resolve. It is also worth noting that in the video transmission distance is short (typically 150 meters), using the impedance mismatch and distribution parameters of the video cable is too large will not necessarily appear above the interference. The fundamental way to solve these problems is in the purchase of video cable, be sure to ensure quality. When necessary, should the cable be sampled and tested.

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