A radio has a tunable bandpass filter that is tuned by apparatus within the radio.
A reference generator generates a reference signal for use in tuning the tunable
bandpass filter. The tunable bandpass filter receives the reference signal and
provides a filter output signal. A digital signal processing and control processor
is connected to the tunable bandpass filter to receive the filter output signal.
The digital signal processing and control processor has a phase comparison function
that provides a phase error metric from the filter output signal. The digital signal
processing and control processor tunes the tunable bandpass filter to provide a
desired phase error metric signal thereby tuning the tunable bandpass filter to
the desired center frequency. The digital signal processing and control processor
stores tunable filter parameters for the desired center frequency. The tuning process
may be repeated for several desired center frequencies of the tunable bandpass filter.