Radio frequency modem and method

A radio frequency modulator/demodulator comprising:

• receiving section means for producing a demodulated data output signal from a modulated R.F. signal received on an R.F. data link, said receiving means including
• local oscillator means for generating a local oscillator signal;
• mixer means for combining said local oscillator signal and said received R.F. signal and producing an intermediate frequency signal;
• variable gain amplifier means for amplifying said intermediate frequency signal with a gain which is a function of an automatic gain control signal;
• detector means for demodulating said amplified intermediate frequency signal;
• digitizing means for receiving a demodulated output signal from said detector means and for producing a digital data output signal, said digitizing means including
• (a) first peak signal means for producing a first peak signal representative of a maximum excursion of said demodulated output signal in a first direction, said first peak signal means comprising a first comparator circuit;
• (b) second peak signal means for producing a second peak signal representative of a maximum excursion of said demodulated output signal in a second direction opposite said first direction, said second peak signal means comprising a second comparator circuit;
• automatic gain control signal generating means for producing said automatic gain control signal indicative of the amplitude of said demodulated output signal in response to said first peak signal, said automatic gain control signal generating means comprising a third comparator circuit;
• and
• transmitting section means for producing a modulated R.F. signal output signal on the data link utilizing an input data signal.