Patent ID: 6188716
Filing Date: 2001-02-13
Classification: H04B,H04L

Abstract:
A radio receiver for receiving a signal having a carrier phase shift key modulated by a subcarrier derived coherently from the carrier wherein data is modulated onto the subcarrier, said receiver comprising:a. a controllable frequency reference adapted to provide a local oscillator signal having a frequency substantially the same as a frequency of the carrier;b. frequency scaler circuitry associated with said frequency reference and adapted to provide a scaled signal derived from the frequency reference and having a frequency substantially the same as the frequency of the subcarrier;c. first mixing circuitry adapted to demodulate a received signal using the local oscillator signal to provide the data modulated onto the subcarrier;d. second mixing circuitry adapted to demodulate the data modulated onto the subcarrier using the scaled signal to provide demodulated data; ande. signal comparison circuitry adapted to compare a function of the scaled signal and a function of the subcarrier to provide a control signal to said controllable frequency reference proportional to any difference between the function of the scaled signal and the function of the subcarrier;said controllable frequency reference adapted to regulate the local oscillator signal according to the control signal to lock on the carrier of the received signal.