卫星导航增强系统中一种天线阵抑制多径方法研究

本文对卫星导航增强终端的天线阵多径抑制方法展开研究,设计多相关器数字接收机结构.天线阵各阵元接收信号数字化后,在导航接收机的每个通道内,相关处理出各阵元接收该通道跟踪卫星的载波相位,进行相干信号二维来波方向估计、数字波束形成,跟踪相应卫星信号,抑制其多径.本文研究分析了立体阵来波方向估计方法,及立体阵估计相干来波方向的去相干方法.电偶极子组成立体天线阵——球体阵,接收相干来波,体积小,结构紧凑.X,Y,Z轴三个线阵分别采用前后向平滑技术去相干,组成去相干后的接收数据相关矩阵,用MUSIC方法估计出相干来波的二维方向,不需要对估计出的来波方向进行匹配.结合卫星直达信号来波方向的导航电文处理结果,确认多径的来波方向.本文仿真中用估计出的卫星直达信号来波方向和多径信号来波方向形成权值,使天线阵波束形成指向卫星直达信号方向,零陷指向多径入射方向,抑制多径干扰.

Antenna array multipath mitigation method in navigation augmentation system

This paper presents the antenna array multipath mitigation method in the satellite navigation augmentation system.The digital receiver with multiple correlators is proposed.The antenna elements of the array each output the raw sampled digital data to every internal receiver channel.The carrier phase of the satellite is correlated out in the channel,and the direction of arrival is estimated,then the digital beamforming is operated to mitigate the multipath.The direction of arrival estimation and the decorrelation method of the correlated signal of the three dimensional array are researched in the paper.A three dimensional spheriform array with current dipoles is proposed,receiving the correlated signals.The three dimensional array proposed is compact with small volume.The linear arrays on X axis,Y axis and Z axis adopt the forward-backward spatial smoothing technique to decorrelate the signals respectively.The direction of arrival is estimated by MUSIC,and there is no matching needed.Distinguish the direct satellite signal by the result of demodulated navigation message.In the simulation,the direction of the direct satellite signal and the multipath signals estimated are used to optimize the weights to apply the beamforming to the desired satellite,and place a null on the estimated multipath direction.