One bit digital phase shift keyed carrier recovery and demodulator

Abstract

A phase shift keyed carrier recovery and demodulator circuit which includes a phase detector and subsequent feedback control loop circuitry which maintains an initial phase relationship. By comparing an incoming phase modulated carrier with the multiple phase outputs of a local oscillator, the circuit is able to generate a correcting signal which allows coherent phase tracking of the incoming phase modulated carrier. The phase detector produces a correction signal which allows the circuit to phase lock any two sequential phases of the locally generated phase outputs to phase positions on either side of the phase of the incoming phase modulated carrier. Once the circuit has obtained carrier phase lock, the multiple phases produced by the local oscillator will remain fixed (without phase change) relative to the initial detected phase of the incoming phase modulated carrier. Since the local oscillator is fixed (locked) to the phase of the incoming phase modulated carrier, demodulation can be accomplished simply by clocking one or more flip flops with respective phases of the local oscillator.