It is of great significance to improve the quality of the monitoring system and ensure the stable operation of the system how to take corresponding measures to solve the problems according to different fault situations.Below is some personal engineering experience to talk about the common failure points of video surveillance system and troubleshooting experience.

　　1, because the connection between the security monitoring system equipment involves a lot of lines, if not handled well, especially with the main equipment connected to the line improper connection or connection error, there will be circuit break, short circuit, poor insulation between the lines, miswiring and other equipment performance decline or damage problems.In this case, the fault phenomenon should be based on calm analysis and troubleshooting, to determine which line connection problems may produce what kind of fault phenomenon.In addition, it should be noted that the connection between the system equipment and various lines should meet the requirements of the monitoring system running for a long time.

　　2. The characteristic impedance mismatch of the transmission cable may lead to a number of equally spaced vertical bars of interference on the monitor picture, and the frequency of the interference signal is basically an integer multiple of the line frequency.This kind of interference is caused by the fact that the characteristic impedance and distribution parameters of the video cable do not meet the requirements.For such interference, the impedance of each device in the system should be matched as far as possible. In particular, the quality of the cable should be ensured when choosing the video cable. If necessary, the cable should be sampled and tested.

　　3, communication interface or communication protocol and other parameters are not set, this situation often occurs between the control host and the decoder or control keyboard and other devices with communication control relationship.That is to say, the selection of the control host and decoder or control keyboard, in the project installation is not set good communication protocol and other parameters caused by, therefore, the host, decoder, control keyboard, etc. in the installation should pay attention to the setting of parameters such as communication protocol.

　　4. Common faults of video interference.

　　· A black or white bar appears on the monitor screen and scrolls up or down, which is the so-called 50Hz power frequency interference.This interference is caused by the improper grounding of the front-end and the control center of the two equipment to form a potential difference loop into the system, but also may be caused by the equipment itself power supply performance decline;

　　· Snowflake noise in the image, which is mainly caused by signal attenuation on the transmission line and coupled high-frequency interference;

　　· The video image is ghosting, or the image is whitening, character jitter, or several equally spaced vertical bars are generated on the monitor picture.This is because the characteristic impedance between the video transmission line or the equipment is not 75Ω, resulting in impedance mismatch;

　　· Twill interference, pulsating interference, and power interference.This interference does not drown the normal image in mild cases, but in severe cases it distorts the image and makes it unviewable.The causes are many and complex, such as the poor quality of the video transmission line, especially the poor shielding performance, or the clutter of the power supply system, or there may be a strong interference source near the system;

　　· Large area reticulate interference, also known as single-frequency interference.This phenomenon is mainly due to the fault caused by the short circuit or open circuit between the core wire of the video cable and the shielding network, or due to the poor contact of the BNC connector.

　　5. Equipment failure caused by power supply problems mainly has the following possibilities:

　　· Incorrect supply line or supply voltage;

　　· Insufficient power (or the line diameter of a power supply line is enough, or the buck is too large, etc.);

　　· The transmission line of the power supply system appears short circuit, open circuit, instant overvoltage, etc.