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由于多径效应的存在,雷达在低仰角跟踪时除了接收到目标的直接回波外,还会接收到与直接回波相干的地(海)面反射的多径信号。针对存在阵元间互耦情况下的米波雷达低仰角测高问题,本文提出了一种改进的加权空间平滑算法。首先,通过特殊的子阵划分方式,使互耦误差和波达方向估计的代价函数无关,使之转化为无互耦误差条件下波达方向估计问题。然后,直接利用阵列接收数据求得最优加权矩阵,对子阵输出的自相关矩阵和互相关矩阵进行加权空间平滑,改善解相干的性能,提高存在互偶误差情况下米波雷达低仰角波达方向估计的精度。理论分析和计算机仿真都表明了新算法的优越性。
Due to the multipath effect, the radar receives the direct echo of the target at low elevation angle and receives the multipath signal reflected by the ground (sea) surface that is directly related to the direct echo. In order to solve the problem of altimeter elevation at low altitude, the paper proposes an improved weighted spatial smoothing algorithm. First of all, through a special subarray division method, the mutual coupling error and the cost function of DOA estimation are irrelevant, so that it can be converted into the DOA estimation problem without mutual coupling error. Then, the optimal weighted matrix is obtained by using the received data of the array directly, and the autocorrelation matrix and the cross-correlation matrix of the output matrix are weighted and space smoothed to improve the performance of the decorrelation so as to improve the low elevation angle Accuracy of direction estimation. Both theoretical analysis and computer simulation show the superiority of the new algorithm.