北斗三号B1C信号标称失真对测距性能的影响

Influence of nominal distortion of Beidou-3 B1C signal on ranging performance

北斗三号系统选择B1C信号作为民用导航信号,并在B1频段采用复杂的恒包络调制,因此,在信号生成过程中极易产生标称失真现象,各卫星标称失真产生的测距偏差不一致现象会直接影响系统定位性能。针对B1C信号提出完整的测距偏差估计方法,首先,以S曲线过零点偏差定量分析B1C信号测距偏差,提出标准相关曲线估计法实现相关曲线尖峰处码相位偏差准确估计;其次,设计算法解决QMBOC信号在接收机跟踪过程中,平台处误锁问题;最后,采用国家授时中心40m高增益天线采集卫星下行信号,分析北斗三号各在轨卫星实际测距偏差及系统星间自然测距偏差随用户接收机不同相关间隔和前端带宽的变化规律,并给出了接收机的建议参数范围。所提策略可扩展到其他MBOC信号测距误差估计,实验结果可为北斗三号接收机研制提供参考。

The B1C signal is selected as a civil navigation signal for the BDS-3 system,which adopts a complex constant envelope modulation in the B1 frequency band.Therefore,it is easy to generate nominal distortion during signal generation.Such nominal distortion of each satellite produces inconsistent ranging deviation and directly degrades the system positioning performance.A complete ranging deviation estimation method was proposed for B1C signals in this paper.Firstly,the S-Curve Bias(SCB)was used to quantitatively analyze the B1C signal ranging deviation,and the standard correlation curve estimation method was proposed to realize the accurate estimation of the code phase deviation at the peak of the correlation curve.Secondly,a algorithm was designed to solve the problem of QMBOC signal mislocking at the platform during receiver tracking.Finally,the actual ranging bias and nature ranging bias of each satellite of Beidou-3 under different correlation intervals and front-end bandwidth of the user receiver were analyzed based on the satellite downlink signals collected from the 40-meter high-gain antenna at the National Time Service Center,and the recommended user receiver parameter range was given.The strategy proposed in this paper can be extended to other MBOC signal ranging error estimation,and the test results can be thought of as a reference to the development of BeiDou-3 receiver.