Psr is a radio detection equipment that provides information on range and bearing of aircraft in the form of a target blip on the radar screen to air traffic controllers by transmitting radar pulses and detecting the reflected signals from the aircraft . no active transponder or avionics on board aircraft has to be relied on 监察雷达发出雷达脉冲，侦测从飞机反射回来的信号，便可计算飞机的距离及方位，并以目标点在雷达屏向航空交通管制员显示，而不须依靠航机上的应答机或其他航空器材。
The traffic alert and collision avoidance system ( tcas ) is a system independent of ground equipment , which is used to avoid middle - air collision . this system can detect all the aircrafts equipped with the atc transponder within a range . it provided traffic advisory to the pilot if some aircrafts close to it , and also provides vertical resolution advisory to the pilot to avoid collision Tcas是一种不依赖地面设备的空中交通防撞系统，它能够探测在其领域内装有空中交通管制应答机( atc )的任何飞机，向驾驶员报告潜在的相撞目标，并发出垂直防撞指令。
