PLL synchronized time-varying constrained notch filter for retrieving a weak multiple sine signal jammed by FM interference

A method of retrieval of a multitone corrupted by a strong wideband FM interference is presented. The input mixture is transformed into a new time domain, resulting in a concentration of the FM interference around a chosen frequency; this inference is then rejected by a constrained notch filter with a fixed notch point. The time warping is implemented through nonequally spaced sampling. The method provides results superior to those of conventional adaptive processing, which fails to track the parameters of an FM interference with significantly large frequency deviations