Patent ID: 7949082

Claim:
In a phase lock loop in a communication system receiver for maintaining synchronization of the local oscillator of the receiver with the oscillator of a transmitter in response to the receipt of a communication signal by the receiver from the transmitter, where said phase lock loop produces a phase error signal responsive to the difference between the phase of the received communication signal with the phase of a reference signal produced by said local oscillator and automatically adjusts the phase of the reference signal responsive to the phase error signal, the improvement comprising only adjusting the phase of the reference signal responsive to a determination that the phase error is less than a predetermined threshold value, and preventing the phase error signal from adjusting the phase of the reference signal while producing an unadjusted reference signal at the local oscillator, responsive to a determination that the phase error is greater than a predetermined threshold; wherein the determination that the phase error is less than the predetermined threshold value is accomplished by comparing the output of a quick decision circuit with the output of a Viterbi decoder.