高精度事件计时器及其在卫星激光测距应用

高重复率卫星激光测距需采用事件计时方式记录激光发射和接收时刻,作为测距系统精密计时单元。本文介绍了事件计时器测量原理,以及上海天文台基于时间数字转换(TDC)和现场可编程门阵列(FPGA)所设计开发的高精度事件计时器。对该事件计时器性能进行了测试,计时精度优于10 ps,非线性误差在数皮秒内。利用上海天文台卫星激光测距系统,进行了事件计时器控制软件开发,对地面靶目标和卫星进行了观测。根据国际激光测距数据处理中心反馈,卫星测量误差达到国外同类事件计时器水平,满足卫星激光测距应用要求。

High precise event timer and its application to satellite laser ranging

High repetition rate satellite laser ranging needs to record the laser transmitting and receiving epoch by using the event timing method,which is regarded as the precise timing unit of the ranging system. This paper introduces the principle of event timer,and the high precise event timer designed and developed on the basis of Time Digital Conversion (TDC) and Field Programmable Gate Array (FPGA) in Shanghai Observatory. The performance of the event timer was tested,with the timing accuracy of better than 10 ps,and the nonlinear error of a few picoseconds. Using the shanghai satellite laser ranging system,the event timer control software was developed to measure the ground targets and satellites. According to the feedback from the international laser ranging data processing center,the error of range measurements reaches the accepted level which is similar with the well-known A033-Event Timer developed by Latvia,and meets the application requirements of satellite laser ranging.