外部参考信号相位差对接收机零值的影响分析

Influence analysis of the phase difference between the output reference signals on receiver zero-value

卫星导航中接收机在使用前要进行零值校准,标记接收机的零值偏差,不同类型接收机的校准方式有所差异,需要研究有针对性的解决方法。本文通过分析接收机的特性,研究了北斗监测接收机(Uni NAV MUE_C_001)的零值校准方法,并搭建了校准平台。试验选用模拟器(Uni NAV GSS8000)对接收机进行校准,在外部输入参考1PPS时间信号和10 MHz频率信号的情况下,接收机零值主要受1 PPS与10 MHz信号相位差(Tt P)的影响。从试验结果来看,连续运行测试时,零值随Tt P的增大而单调递减。开关机测试时,受调钟方式的影响,零值随Tt P的增大而呈周期性变化。试验同时分析了校准的不确定度,受射频滤波器和伪码测距精度的影响,接收机B3频段2.3 ns的不确定度要优于B1、B2频段的2.8 ns。最后对校准的两台接收机进行了零基线比对试验,验证了Tt P与接收机零值的关系,且校准一致性优于0.5 ns。

In satellite navigation the receivers should be zero-value calibrated, and the zero-value offset of the receivers is marked, and the calibration modes of different types of receivers are also different, which should be studied with pertinence solutions. Through analy- zing the characteristics of different types of receivers, this paper studies the zero-value calibration method of the Beidou monitoring receiver （UniNAV MUE C 001 ） , and builds the calibration platform. UniNAV GSS8000 is chosen as the hardware simulator to calibrate the receiver. With the external 1 PPS synchronous signal and 10 MHz reference signal, the receiver zero-value is mainly affected by the phase relation （TtP） between the 1PPS and 10 MHz. From the experiment result, under continuous operation test the receiver zero- value is monotonously decreasing as TtP increases. However, under on-off operation test the receiver zero-value presents periodic variation as TtP increases, which is affected by the mode of clock adjusting. Meanwhile the experiment also analyzes the calibration uncertainty ; affected by RF filter and pseudo code ranging precision, the uncertainty of 2.3 ns in B3 band is better than the uncertainty of 2.8 ns in B1 and B2 bands. At last, the zero-baseline comparison experiment on two calibrated receivers were performed to verify the relation between TtP and zero-value calibration, and the calibration consistency is better than 0. 5 ns.