激光测高仪中基于现场可编程门阵列的高精度飞行时间测量

设计了在激光测高系统中基于单芯片现场可编程门阵列(FPGA)的高精度时间间隔测量模块。该模块采用高频计数器实现粗时间测量,差分延时线内插技术完成细时间测量,时间分辨率为300 ps。该芯片同时还集成了时序切割电路、回波脉宽测量和数据传输模块等。在环境温度20℃时对该测量模块进行精度测试,获得标准偏差为94.68 ps,转换成距离为1.42 cm。最后通过地面检测,整个系统在500 km范围内的一般条件下可获得测高精度±50 cm。

High-Resolution Measurement of Flight Time for Laser Altimeter Based on Field Programmable Gate Array

A high-resolution flight time measurement system based on a single field programmable gate array (FPGA) in laser altimeter is designed. The time resolution of 300 ps is obtained, because the differential delay lines are used to perform interpolation and to realize the fine time measurement, and high frequency counter is designed to perform the coarse time measurement. The time splitting circuit, pulse width counter and data transmitter module are integrated in the same chip. At an ambient temperature of 20 ℃, we achieve a standard deviation of 94.68 ps which equals to 1.42 cm in distance. Furthermore, detection on the ground verifies the feasibility of measuring distance with ±50 cm resolution over 500 km ranges under general conditions.