CARRIER WAVE EXTRACTION CIRCUIT

摘要

PROBLEM TO BE SOLVED: To surely extract a carrier wave having a large extent of frequency deviation without dropout with a smooth continuous phase. SOLUTION: A QPSK modulation signal is multiplied by 4 in a 4-multiplying circuit 1 and passes a BPF 2 and is supplied to a binarizing circuit 3 and is made into a binary signal. The BPF 2 has a pass band which allows passage of a deviated carrier frequency of the output signal of the 4-multiplying circuit 1. The binary signal from the binarizing circuit 3 has a dropout period where the vector of the input QPSK modulation signal is 0, and the phase is inverted at 180 deg. before and after the dropout period. The binary signal from the binarizing circuit 3 has the frequency divided by 4 in a 4-frequency division circuit 4 to reduce the phase change before and after the dropout period to 45 deg., and the binary signal is made to pass a BPF 5 having a pass band of a maximum extent of frequency deviation of the carrier wave of this binary signal, and thus the dropout period is interpolated.