An automatic gain control includes a digital lowpass filter for filtering a series
of digital samples generated by an analog-to-digital converter to generate a lowpass
filtered digital sample series; a power averager coupled to the digital lowpass
filter for calculating an average power of the lowpass filtered digital sample
series; and a lookup table coupled to the power averager for setting a selectable
gain of an amplifier coupled to the analog-to-digital converter as a function of
the average power.