基于副载波参考波形方法的GNSS双载波环多径抑制技术

为了实现对高阶BOC信号的无模糊和抗多径接收，本文将码相关参考波形的闸波设计思路应用于GNSS双载波环路接收方法的副载波锁相环，通过在副载波锁相环中引入设计的闸波参与信号的相干积分过程，使双载波环法具备抗多径性能，同时该方法并不需要额外引入相关器。本文对该设计方法的理论和具体实现进行了阐述和分析，从副载波多径误差包络和跟踪精度两方面对改进的双载波环路方法性能进行了评估。仿真结果显示，采用的算法与双载波环路法相比可以降低BOC(1, 1)信号81.1%的副载波多径误差包络面积，以及BOC(14, 2)信号75.1%的副载波多径误差包络面积。但是，改进的双载波环路法将带来-6dB的相干积分后载噪比损失，降低跟踪精度。因此，在闸波设计参数设计上，需要谨慎选择以平衡算法的多径抑制和跟踪精度性能。综合来看，该方法适用于解决非弱信号条件下及多径环境下的高阶BOC信号接收问题。

Multipath mitigation technique of GNSS double phase estimator based on subcarrier reference waveform method

Based on the strobe pulse method, the double phase estimator (DPE) was modified by introducing a strobe waveform in the prompt signal correlation process of the subcarrier phase lock loop (SPLL) integration. The design of this strobe waveform in SPLL aims to enhance the multipath error mitigation performance of the DPE, and its theory is explained and analyzed. The performance of the modified DPE is characterized according to the subcarrier multipath error envelope (SMEE) and the tracking jitter. Simulation results show that, relative to conventional DPE, the waveform employed in this study respectively provides a reduction in the SMEE of 81.1% and 75.1% for a binary offset carrier (BOC) signal with a subcarrier to reference frequency ratio of 1 and a PRN code to reference frequency ratio of 1 (i.e., BOC(1, 1)) and a BOC(14, 2) signal. However, the modified DPE experiences a loss of -6 dB in terms of the post-coherent signal-to-noise ratio, which impacts its tracking precision. Thus, the selection of waveform parameters involves a trade-off between the tracking performances obtained under multipath and thermal noise conditions. Above all, the proposed method is applicable to the receiving situations of multipath environment or non weak signal case.