| 摘要 |
PROBLEM TO BE SOLVED: To provide a phase modulation wave signal demodulator which achieves stable symbol clock phase synchronization even at carrier asynchronous time in demodulation of a PSK modulation wave signal with small amplitude fluctuation and can reproduce a more accurate symbol clock.SOLUTION: A modulation wave signal is detected in an in-phase detection circuit 12 and an orthogonal detection circuit 13, is digitized in A/D converters 17 and 18, is supplied to a complex multiplier circuit 19 as in-phase axis detection output and orthogonal axis detection output, is spectrum-shaped and is supplied to a symbol clock reproduction circuit 137 via a complex multiplier circuit 22. In the symbol clock reproduction circuit 137, an instantaneous phase angle for each sampling timing is calculated, a change point of a symbol is detected by differential processing of the instantaneous phase angle and a symbol clock is reproduced. Since a sampling rate is sufficiently larger compared to an offset frequency of a carrier frequency, an offset phase of the carrier frequency is canceled by the differential processing. |
