基于GNSS模拟器的加速度辅助跟踪实验验证

具有外部辅助信息的接收机跟踪环路可以提高接收机的动态范围、跟踪灵敏度与抗干扰性能,但由于目前开展实际高动态实验非常困难,故不方便对辅助效果进行实际信号的测试。介绍了一种基于GNSS信号模拟器高动态场景采集的卫星信号与辅助信息,在软件接收机中进行捕获与跟踪处理的测试方法,其中辅助信息为用户-卫星视线速度和加速度。实验过程中采用一种根据捕获多普勒频率进行时间对齐的方法,将卫星信号和采集时间存在延迟的辅助信息进行粗略对齐。在介绍传统的速度辅助方法和一种新的加速度辅助方法基础上,分析辅助信息时间延迟对辅助结果的影响,最后基于上述数据分别测试并对比无辅助、速度辅助和加速度辅助的跟踪环路性能。结果表明,由于经粗略对齐后的辅助信息相比卫星数据仍存在约1.3 s的时间延迟,导致速度信息无法辅助高动态卫星信号跟踪,而采用加速度辅助方式可将30 Hz带宽环路的跟踪误差从0.031周减小到0.020周,最小跟踪带宽从22 Hz降低至10 Hz;加速度辅助的20 Hz带宽环路跟踪误差为0.029周。因此,加速度辅助方式可减弱辅助信息时间延迟对高动态信号辅助跟踪效果的影响,对于高动态接收机的工程实现有实际意义。

Experiment validation of acceleration aided tracking method based on GNSS signal simulator

GNSS tracking loop with external aiding information can improve the dynamic range,tracking sensitivity and anti-jam performance.Due to the difficulty of performing high dynamic experiment,it’s not convenient to validate the aiding effect with real high dynamic signal.This paper investigates a test method based on satellite signal and aiding information collected in GNSS signal simulator,with signal acquisition and tracking in software receiver.The aiding information includes user-satellite line-of-sight velocity and acceleration.An alignment method based on acquired Doppler frequency is adopted to align the satellite signal and the time delayed aiding information roughly.On the basis of introducing traditional velocity aiding method and a new acceleration aiding method,the effect of time delay on aiding performance is analyzed;finally the tracking performances of the tracking loops without aiding,with velocity aiding and with acceleration aiding are tested and compared using the above data.According to the results,due to the remaining time delay of about 1.3s after the roughly alignment,velocity aided tracking loop can not work effectively.Compared with tracking loop without aiding,the acceleration aided tracking loop with 30 Hz bandwidth can reduce the tracking error from 0.031 cycle to 0.020 cycle and the minimum tracking bandwidth is decreased from 22 Hz to 10 Hz.The tracking error of acceleration aided tracking loop with 20 Hz bandwidth is 0.029 cycle.Hence,acceleration aiding method can weaken the effect of aiding information time delay on the aiding performance of high dynamic tracking,which has great value to the engineering implementation of high dynamic receiver.