FREQUENCY DEVIATION CORRECTION CIRCUIT

摘要

PROBLEM TO BE SOLVED: To correct a phase deviation by calculating an average phase shift based on a 1st signal obtained by correcting an input signal with a large frequency deviation between a carrier frequency and a reference frequency whose C/N is deteriorated and selecting a correct reference frequency. SOLUTION: In the case of receiving an input signal where its waveform is distorted in comparison with an ideal waveform due to a shifted phase of the input signal caused by a deviation between a carrier frequency and a reference frequency resulting in deteriorating the C/N, a subtractor circuit 1 provides a 1st signal correcting a phase shift of the input signal with a 1st correction latch signal outputted from a correction latch circuit 3 at first. Then a correction value calculation circuit 2 calculates an average phase displacement based on the 1st signal. The average phase displacement is received by a correction value latch circuit 4 and outputted to a subtractor circuit 5. The subtractor circuit 5 corrects further the 1st signal with a 2nd correction value latch signal. Thus, a reference phase closest to a phase when the C/N of the 1st signal is deteriorated is correctly calculated.