Patent ID: 7209532

Claim:
The method of maintaining phase lock of a receiver with a transmitter in a communication system wherein the receiver receives a communication signal comprising a carrier signal and an encoded data signal from the transmitter, comprising the steps of: (a) decoding the received communication signal with a Viterbi decoder with trace back to thereby produce a first data signal; (b) providing a look up table for producing a second data signal responsive to the first data signal; (c) delaying the received communication signal by an amount of time substantially equal to the trace back delay in the Viterbi decoder to thereby produce a delayed signal; (d) extracting the encoded data from the delayed signal thereby producing a third data signal; (e) mixing the second data signal with the delayed signal to thereby remove the encoded data signal and provide the carrier signal; (f) comparing the phase of the carrier signal with the phase of a reference signal to thereby produce a phase error signal responsive to the difference in phase between the carrier signal and the reference signal; (g) comparing the first data signal with the third data signal to thereby produce a control signal if the comparison of the first and third data signals satisfies a predetermined criteria; (h) selectively applying the phase error signal to a feedback loop, responsive to the presence or absence of said control signal, to thereby maintain phase lock of the receiver with the transmitter.