CARRIER RECOVERY APPARATUS

摘要

A carrier recovery apparatus for phase modulated carrier waves is disclosed. A voltage controlled oscillator provides a variable frequency signal in response to a control signal and a first phase comparator provides a comparison output between an input modulated carrier and the variable frequency signal. A loop filter supplies the voltage controlled oscillator via a frequency multiplier with the low frequency component of the output of the first phase comparator, the low frequency component serving as the control signal. A clock recovery circuit generates a clock signal in response to the modulated carrier. A second phase comparator provides a comparison output representative of the phase difference between the output of the first phase comparator and the recovered clock signal. The low frequency component of this comparison output is superimposed on the output of the first phase comparator or the loop filter. The invention substantially eliminates false locks and provides a stable recovery function even under stringent band conditions.