Nonlinear median based receiver for QAM signals

A nonlinear detection scheme for coherent PAM (pulse amplitude modulation) and QAM (quadrature amplitude modulation) is developed. The detector is based on a median-type digital filter, called a matched median filter, which is the natural counterpart of the linear matched filter in the class of median-type filters. These filters are optimal for Laplace noise, and it is shown that they lead to a robust detection scheme which also performs well when strong impulsive noise corrupts the signal. Formulas for detection error probabilities are derived, and simulation results confirming the expected behavior of the detector are presented