Front-end device interference
Front-end camera power supply interference, camera itself quality problems caused by interference, the judgment method is directly in the front-end monitor observation, if the interference caused by the power supply can be replaced by switching power supply, the use of the switch in 220V AC filter and other methods to solve.
Power supply interference, mainly in the following cases:
1) 50Hz power supply interference, due to both ends of the grounding potential and the existence of cable outer resistance, between the two places caused by 50Hz of potential difference, resulting in dry
Disturbing signal voltage. When the jamming signal is superimposed on the video signal, a wide transverse dark band appears on the normal image.
2 Not Clean power interference, here refers to the power supply is not "clean" refers to the normal power supply (50 weeks of sine wave) superimposed on the interference signal. and the interference signal on this power supply, from the use of SCR equipment in the power grid, especially the large current, high voltage thyristor equipment, the pollution of the grid is very serious, which led to the same power grid is not "clean".
3 50Hz power supply frequency two harmonics and three harmonic interference: harmonic interference is mainly manifested in the large current or high voltage power line around, is the electric cable to the surrounding radiation signal, its frequency is 2500Hz and 125000Hz, mainly interfere with the low-frequency segment of the video signal.
When it comes to harmonic interference, we have to talk about the unavoidable interference of the broadcast signal in the transmission process. Broadcast signal interference is very strong, is also very common, due to the actual application needs, and must be installed in the air cable, when the cable itself is equivalent to a very long antenna. As a result of the antenna effect, the voltage of the broadcast jamming signal will be generated on the terminal load, and the jamming signal can be mixed into the video signal. This jamming signal is shown as a dense diagonal pattern in the image, and it can even drown the image when it is serious.
Transmission process Interference
Mainly transmission cable damage caused by interference, electromagnetic radiation interference and ground interference (ground potential difference), such as three kinds of transmission cable can be replaced by cable or increase anti-jamming equipment to solve.
Terminal Equipment interference
Mainly is the power supply of the monitoring room, the disturbance caused by the equipment itself, the interference caused by grounding, the interference of equipment and equipment connection, and so on, the simple judgment method is to connect the camera directly in the monitoring room.