| 摘要 |
PURPOSE:To eliminate an error output of a demodulator without phase shift from a reproducing circuit, by providing a circuit which multiplies output components multiplied directly and via a filter compensating the shift in carrier wave components and frequency-divides them. CONSTITUTION:A modulation wave of a minimum shift keying (MSK) system is multiplied by two at a frequency multiplier DBL and the frequency components are applied to BPFs 1 and 2 at a hybrid circuit H1. Frequency components (2omega1t1+DELTAtheta) and (2omega2t+DELTAtheta) only are picked up at the BPFs 1 and 2, they are multiplied at a multiplier ML1 and applied to the 2nd hybrid circuit H2. The output component is the circuit H2 is directly added to a multiplier ML2, the other is applied to a BPF4 compensating the carrier frequency, and an output frequency-dividing the output of the BPF4 at a 1/2 frequency-divider DV2 is applied to the multiplier ML2. The output from the multiplier ML2 is applied to a BPF5, 2omega0t only is outputted from the BPF5 and a reference carrier wave without phase shift can be outputted from the 3rd frequency divider DV3. |
