HD surveillance camera requirements

The surveillance camera system must be HD

In addition to the attention to front-end installation and material selection, the high-definition camera must also have a transmission system. Only when the intermediate system and the terminal display system are used together can the actual effect of high-definition be achieved.

For high-definition surveillance camera systems, the transmission of video images generally chooses coaxial cable, twisted pair, UTP line (that is, network transmission), wireless transmission, optical cable transmission, etc. No matter which method is adopted, the image must be transmitted from The bandwidth of each loop in the entire system transmitted from the front end to the back end is> 6M, so as to ensure that the image reaches the high-definition requirements and meets the requirements of engineering and technical defense detection. Under normal circumstances, the image quality will be significantly reduced when the coaxial cable exceeds 150 meters or 200 meters. This is due to the characteristics of the coaxial cable itself. Therefore, various measures must be taken to ensure that the terminal bandwidth is not less than 6M. Video compensation amplifier to solve, the general video amplifier has little effect. The compensation index should ensure that the amount of high-frequency compensation, amplitude-frequency characteristics, signal-to-noise ratio, common mode rejection ratio, differential phase distortion, chroma brightness delay, chroma width gain, etc. are all caused by the loss or attenuation of the relevant cable The defects are compensated to ensure high definition of the image entering the system.

At present, due to the rising price of copper cables, the cost of using video cables to transmit video images continues to decline. In the transmission of longer distances or multiple images, the use of optical cables for transmission is a multi-purpose solution that is widely used. Due to the characteristics of large bandwidth, small attenuation, high anti-interference, small size and strong confidentiality of the optical cable, it can better ensure the various indicators of image transmission. When transmitting images in other ways, the bandwidth of the channel must also be guaranteed.

High-definition images must also be displayed in front of human vision with good terminal display equipment, so it is best to choose a progressive scan monitor. Because in actual use, the image of the interlaced scanning monitor flickers severely, which may easily cause visual fatigue. If the definition of the monitor is low, the requirement of the overall definition cannot be reached. Because the resolution of the monitor is determined by the bandwidth of the monitor and the video channel and the dot pitch and meeting distance of the kinescope. According to the data, the theoretical upper limit of the conversion between the channel bandwidth and the resolution is about 1M / 80 lines. If the factor of the video signal amplitude reduction at high resolution is considered, if the video image of 400 lines is displayed, the monitor is clear According to experience, the index should be more than 600 lines. In order for the high-definition camera system to work properly, intermediate processing equipment, including matrix, hard disk recorders, video servers, various video encoders, etc., must meet the requirements of bandwidth and image compression, so that high-definition cameras can fully utilize their inherent effect. Relying on the use of high-definition cameras and ignoring the selection of other ancillary equipment cannot achieve the real purpose.