ADAPTIVE INTERFERENCE TRACKER FOR SUPPRESSION OF NARROW BAND INTERFERENCE

Adaptive filtering of narrow band interference is achieved by means of a circuit that automatically estimates the amplitude and frequency of narrow band interference in the presence of a wide band signal. The estimate of the interference is subtracted from the input signal. Sample data baseband signals are processed in order to estimate the frequency and amplitude of interfering signals. The filter employs two tracking loops which act together to provide a second order tracking function. The first tracking loop provides a smoothed estimate of the interference. The second tracking loop provides a signal that adjusts a phase shifter to track the interfering signal frequency. Subtraction of the estimated interference from the input signal provides an output signal with attenuated interference and that is only slightly distorted.