基于小波包分解重构算法的北斗抗多路径误差

针对北斗卫星导航系统（BDS）特有的多星座设计而形成的复杂多路径误差问题,本文提出了一种基于小波包（WPT）分解重构原理的抗多路径误差算法,来提高BDS定位精度。首先,将原始信号进行多层小波包分解,得到多个子频带,并根据各子频带和原信号的互相关系数大小,将其划分成噪声频带、混合频带和信息频带等;其次,舍弃噪声频带,保留有效成分集中的信息频带,并对混合频带进行软阈值滤波处理;最终,将滤波后得到的“干净”数据与信息频带进行重构,从而实现削弱BDS多路径误差的目的。通过数值仿真和实测实验分别验证所提算法的有效性,实验结果表明,采用WPT算法对BDS实测数据进行处理后,N、E、U三个方向精度分别提升77%、78%、83%,有效削弱了多路径误差对BDS定位精度的影响,研究结果对BDS高精度定位具有重要参考价值。

Research on anti-multipath error of BDS based on WPT decomposition and reconstruction algorithm

Aiming at the complex multipath error problem caused by the unique multi-constellation design of BDS, an anti-multipath error algorithm based on wavelet packet (WPT) decomposition and reconstruction principle is proposed in this paper to improve the positioning accuracy of BDS. Firstly, the original signal is decomposed by multi-layer wavelet packet to obtain multiple sub-bands, which are divided into noise frequency band, mixed frequency band and information frequency band according to the correlation number between each sub-band and the original signal. Secondly, the noise frequency band is discarded, the information frequency band of active component is retained, and the mixed frequency band is filtered by soft threshold. Finally, the "clean" data and information frequency band obtained after filtering are reconstructed to reduce the BDS multipath error. The effectiveness of the proposed algorithm is verified by numerical simulation and field experiment. Experimental results show that the accuracy of N, E and U directions is improved by 77%, 78% and 83% respectively after the WPT algorithm is used to process the measured data of BDS, which effectively weakens the influence of multipath error on the positioning accuracy of BDS. The research results have important reference value for high precision positioning of BDS.