视频监控系统是ITS的重要组成部分之一。高速公路项目中对视频信号传输的要求有以下特点:一是容量大。在一个监控分中心通常有几十路甚至上百路视频信号;二是图像质量要求高。图像要求达到480线,加权信噪比S/N要求不小于57dB;PAL制图像要求达到25帧(50场/s)、NTSC Video surveillance system is an important part of ITS. Highway project requirements for video signal transmission has the following characteristics: First, large capacity. In a monitoring sub-center there are usually dozens of even hundreds of road video signal; the second is the high image quality requirements. Image requirements of 480 lines, weighted S / N requirements of not less than 57dB; PAL system requires 25 frames (50 fields / s), NTSC