A radio receiver (100) has an IF (intermediate frequency) filter (200)
for automatically adjusting its intermediate frequency. The filter (200)
includes a filter bank (304), an accumulative sub-band formation (322)
and an accumulative sub-band power estimator/switch control (324). The filter
bank (304) generates sub-bands, each sub-band having a predetermined frequency
range. The accumulative sub-band formation (322) selectively sums the sub-bands
to provide lowpass filters having incrementally increasing bandwidth. Power estimates
of the lowpass filters are used to determine which lowpass filter output is appropriate
for adjacent station interference. Also, if there is no adjacent station interference,
the IF filter (200) selects the appropriate filter output depending on the
signal strength of the desired station.