伪码测距系统的多普勒频移补偿

卫星所搭载的再生伪码(pseudo-noise,PN)测距系统已广泛应用于测量双星或星地距离,由于星地间的相对运动更为明显导致伪码测距信号存在着较大的多普勒频移,从而影响利用相关运算获得的双程延时测距精度。根据伪码测距系统的实现结构,推导出当多普勒频移存在时的测距延时计算公式,进而提出了一种补偿方法。同时考虑到测距系统的实际应用环境,对补偿公式进行了简化。仿真及实际测试结果表明,经过补偿后的双程延时测量值精度(中强信噪比下)可达到0.14ns(4cm),补偿造成的精度影响为0.01ns(3mm),同时公式简化及补偿引入的误差可以忽略不计。

Compensation of Doppler shift for pseudo noise ranging system

The regenerative pseudo noise ranging system carried by satellites has been widely used to measure the distance between ground and satellites or inter satellites.The existence of the larger Doppler shift due to the more obvious relative motion between ground and satellites influences the dual way time delay ranging accuracy using correlation operations.Based on the regenerative PN ranging structure,we deduce the formula in detail at the presence of Doppler frequency shift and a compensation method is proposed.We simplify the formula according to actual mission conditions.Simulation and test results verify the correctness of the compensation.The ranging accuracy of 0.14 ns (4 cm) with medium signal to noise ratio can be obtained,and the impact of simplification is 0.01 ns (3 mm),which can be ignored.