Direct path wave purification for passive radar with normalized least mean square algorithm

The passive coherent location (PCL) radar detects potential targets by computing the cross ambiguity function (CAF) between the target echo signal and the direct path wave, which is regarded as the reference signal received from the reference channel. However, a number of the multipath interferences present in the reference signal in most cases. The existence of the multipath interferences can increase the false alarm rate and raise the detection threshold giving rise to lower detection rate. Therefore, the direct path wave should be purified. This paper proposes a direct path wave purification algorithm based on the normalized least mean square (NLMS) algorithm. This algorithm can attenuate the multipath interferences of the direct path wave, which results in the lower false alarm rate and lower detection threshold. This algorithm is validated by the experimental results.