基于GPS校准的皮卫星高精度时间系统方案

许多实际应用任务对皮卫星星上时间系统有较高的精度要求，传统采用实时时钟芯片（RTC）的时间系统方案难以满足需求，基于GPS的皮卫星星上时间系统应运而生。受能源限制，皮卫星携带的GPS接收机一般采用间歇性开机方式工作。本文设计实现了一种基于GPS校准的星上时间系统方案，提出了分级校正算法，并对算法中的参数进行了优化，实验表明，每天GPS接收机仅需开机1024 s，即可保证优于1 ms/d的星上时间精度。整个方案实现简单，且已应用于浙江大学研制的ZDPS-2皮卫星，满足了任务载荷5 ms时间精度的要求。

The high-precision time system design of pico-satellite based on GPS receiver

High-precision system time is usually required in many missions of pico-satellite. Traditional solution of timing system based on real-time clock(RTC)chip in pico-satellite cannot meet thisrequirement,therefore GPS re?ceiver(GPSR)is applied in the design of timing system. However,GPSR in pico-satellite cannot work for long time because of the energy limitaiton. Then a design of a timing system based on GPSR which only need to be powered on for a short time has been presented in this paper. An algorithm to calibrate system time for long-term is provided. Experiment shows that the time accuracy is better than 1 ms/d when GPSR works for 1 024 seconds per day. Thisde?sign has been applied in ZDPS-2 satellite,and qualified the mission requirements of 5 ms/d.