Patent ID: 6693969
Filing Date: 2004-02-17
Classification: H03C,H03L,H04L

Abstract:
A method of modulating an information signal onto a transmit signal, comprising the steps of:modulating an intermediate-frequency signal with said information signal to thereby generate a modulated intermediate-frequency signal that has a nonconstant envelope; generating said transmit signal with a phase-locked loop that responds to said modulated intermediate-frequency signal and has a loop filter that determines a loop bandwidth and a voltage-controlled oscillator that is coupled to said loop filter and provides said transmit signal; extracting a phase-correction signal from said modulated intermediate-frequency signal; and inserting said phase-correction signal between said loop filter and said voltage-controlled oscillator to thereby substantially restore modulation phase information to said transmit signal; wherein said phase-correction signal extracting step includes the step of frequency-differentiating said modulated intermediate-frequency signal.