星载激光测高仪接收系统通过收集地表反射的回波信号, 反演卫星与地表的高度。本文提出一种回波模拟光源方法, 产生延时量可调的激光主波和回波周期脉冲信号作为接收系统的检校输入源, 对星载激光测高仪距离参数进行地面标定。首先, 采用主波与回波光电探测器互换的测量方法, 利用频率计数器对回波模拟光源的延时量设定值进行精确测量, 测量方法误差为113 ps。然后, 通过比对回波模拟光源调制的延时量设定值和接收系统测试获取的延时量实测值, 实现对测高误差的标定和校正。研制了一套回波模拟光源系统, 通过3 335 6409~3 669 2050 ns的延时量调制, 实现对500~550 km高度的精确模拟, 模拟延时信号的抖动量为345 ps, 延时偏差小于118 ps, 为百千米级星载激光测高仪提供了高程误差优于6 cm的地面检校能力。

Satellite-borne laser altimeter measures the distance between a satellite and the earth through processing a laser echo signal collected by its receiving module. A laser echo simulation model for the ground-based distance parameter calibration of satellite-borne laser altimeter is proposed, in which the emission laser pulse and the returned laser pulse with an adjustable time-delay are generated. First, the time-delay value set in the laser echo simulation system was precisely measured by swapping two photodetectors and using a frequency counter, and the measurement error was 113 ps. The calibration of the elevation error is realized by comparing the time-delay set value and the time-delay value obtained in the receiving system. A laser echo simulation system is developed that offers distance simulation ability from 500 km to 550 km with a jitter of 345 ps by setting the periodic time-delay from 3 335 6409 ns to 3 669 2050 ns. The time-delay accuracy of the laser echo simulation system for the satellite-borne laser altimeter is better than 118 ps and the system can provide a calibration capability better than 6 cm in the range of hundreds of kilometers.