An adaptive notch filter (ANF) module selectively filters a received
wideband communication signal to eliminate narrowband interference that
lies within the frequency spectrum of the wideband communication signal.
To determine the presence of narrowband interference, the ANF module
scans various known narrowband channels that lie within the frequency
spectrum of the wideband communication signal and determines signal
strengths for each of the narrowband channels. The signal strengths from
the narrowband channels are compared to a threshold that is derived from
the narrowband signal strengths. Narrowband channels having signal
strengths that are greater than the threshold are determined to have
interference.