A system for tuning a radio receiver includes a radio receiver configured
to provide a downconverted digital error signal, a digital synthesizer
circuit configured to generate a first local oscillator control signal, a
digital automatic frequency control (AFC) circuit configured to generate
a second local oscillator control signal, wherein the digital synthesizer
circuit is enabled to generate the first local oscillator control signal
when the digital AFC circuit is disabled, the first local oscillator
control signal corresponds to an estimate of a desired local oscillator
frequency, the digital AFC circuit is enabled to generate the second
local oscillator control signal when the digital synthesizer circuit is
disabled and the second local oscillator control signal corresponds to
the desired local oscillator frequency.