采用副载波参考波形方法的GNSS双载波环多径抑制技术

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

为了实现对高阶二进制偏移载波(BOC)信号的无模糊和抗多径接收,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。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且不需要额外引入相关器。对该设计方法的理论和具体实现进行阐述和分析,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会带来-6 dB的相干积分后载噪比损失,降低跟踪精度。因此,在闸波参数设计上,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。

In order to achieve the unambiguous and antimultipath reception of the BOC （binary offset carrier） signal, the DPE （double phase estimator） was modified by introducing a strobe waveform in the prompt signal correlation process of the SPLL （subcarrier phase lock loop） integration. The modified DPE possesses multipath error mitigation performance and employs no additional correlator. The theory and the realization of the proposed approach were explained and analyzed, and the performance of the modified DPE was characterized according to the SMEE （subcarrier multipath error envelope） and the tracking jitter. Simulation results show that, compared with the conventional DPE, the proposed algorithm can provide a reduction in the SMEE area of 81.1% for signal BOC（1,1） and 75.1% for signal BOC（14,2）. 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 problems of multipath environment or non weak signal case.