Abstract: Method and apparatus for reducing the effects of noise jamming on coherent frequency or phase modulated signals employs a two channel radio signal processing system (15, 20) which accepts an input signal containing a desired signal (S) and a jamming signal (J) from a receiver input circuit (10). In the first channel (15), a hetrodyne mixer (30) and wideband filter (35) select the difference frequency component between the jamming signal and the desired signal [X(t)] while in the second channel (20), a local oscillator (45), mixer (50) and filter (55) function to select the difference frequency between the jamming signal and the local oscillator [Y(t)]. A third mixer (90) and bandpass filter (95) combines the outputs X(t) and Y(t) to provide the desired signal, including its original phase and frequency modulation components substantially independent and free of the jamming signal, to the receiver output circuit (12).