随着铁路现代化的进展,铁路通信系统也在不断地改进和发展。铁路通信线路的明线正在被淘汰,电信线路逐步电缆化。由于电缆埋在地下受环境温度影响不大,对外界的影响也很小,所以安全可靠。虽然一次性投资较高,但维护工作少,维修费用省,不过,由于传输特性的改变需要大大地缩短增音站的距离。明线传输一般在80—120km才设置一个,而对称电缆则需要在16—23km左 With the progress of railway modernization, the railway communication system is constantly being improved and developed. The clear lines of railway communication lines are being eliminated, and the telecommunication lines are being gradually cabled. As the cable buried in the ground by the ambient temperature has little effect on the outside world is also very small, so safe and reliable. Although a one-time investment is high, but less maintenance, maintenance costs, however, due to changes in transmission characteristics need to greatly shorten the distance between the pitch station. On-line transmission is generally set at 80-120km, while symmetrical cables are required at 16-23km left