Little knowledge: how to do if there is a black image in the surveillance camera image

When the surveillance camera is installed and used, it often encounters some faults. There are no images, unclear images, focal lengths, etc. Some of these problems are caused by the camera itself, and some are caused by improper installation and use. This article focuses on the analysis of the surveillance camera. There are black map solutions for your reference.

Step/method 1. Camera condition: Analysis of bad transformer causes: excessive instability of power supply. Solution: Replace transformer 2. Camera condition: Cause of bad line: Too many connectors or poor line contact Solution: Replace line 3. Camera status: Analysis of the causes of several vertical stripes with equal spacing: Since the characteristic impedance of the video transmission line is not 75Ω, it results in impedance mismatch. Or by the video cable's characteristic impedance and distribution parameters do not meet the requirements caused by the synthesis.

Solution: Generally rely on the "series resistor connected at the beginning" or "terminal and resistor connected" method to solve.

4. Camera status: Caused by the appearance of grainy interference: The quality of the video transmission line is not good, especially the shielding performance is poor, and the line resistance is too large, resulting in a large attenuation of the signal. Or because the power supply system is not "clean".

Solution: Change the video cable or increase the sleeve. The problem of power supply can basically be solved by using a clean power supply or an on-line UPS for the entire system.

5. Camera status: A black bar or white bar appears on the monitor's screen. Cause analysis: The most common fault phenomenon is 50-cycle power frequency interference. This phenomenon is mostly caused by the system generating a ground loop and introducing 50 weeks of work. The presence of ground loops due to frequency interference (AC interference) may be due to the repeated grounding of the common end of the signal transmission line at both ends; or the short circuit of the common end of the signal line to the neutral of the 220V supply; or There is a short circuit between the common terminal of a certain device and the 220V AC power supply; it is also possible that the signal line is caused by a strong magnetic field generated by the AC power supply (such as if both parties are too close together).

Solution: The solution is to connect the transformer in the form of a vertical choke (also known as a neutral transformer), or to use a "longitudinal choke" on the transmission line to eliminate this type of interference. Camera status: Cause analysis of long line: The line is too long or the signal attenuation solution: Due to the loss of the high-frequency end of the image signal is too large, resulting in the basic loss of signals above 3MHz. In this case, either the transmission distance is too long and there is no amplification compensation device in the middle; or the distribution capacitance of the video transmission cable is too large; or the equivalent capacitance is concentrated in the transmission link between the core wire and the shielded wire. As a result, signal amplifiers should be added.

This article comes from China Security Network: http://news. C-ps. Net/2012/4/99231. Html