Application of the least squares constant modulus algorithm for multipath removal in the FM signal

In Passive coherent location (PCL) radar using FM signal as emitter of opportunity the multipath propagation from transmitter to the reference antenna strongly decreases the radar detection ability. Thus, multipath removal from reference signal is a very important stage of signal processing in radar system. Since the FM signal with constant envelope is used the commonly known constant modulus algorithms suit very well for this purpose. In this introductory paper, we propose to use a block least squares constant modulus algorithm which has better convergence properties then the conventional LMS-type algorithm presented in literature. It appears as very appealing alternative since in further applications (not presented in this paper) it will very likely enable to achieve satisfactory results with less amount of data (signal samples).