| 摘要 |
PURPOSE:To prevent pseudo locking by applying AFC control to a circuit recovering a carrier used when a modulation wave subject to a quadruple phase modulation is subject to synchronization detection and demodulation. CONSTITUTION:A circuit having a 4-phase detector 1, a 1st multi-value identification device 2, a phase error detection circuit 3 and a voltage controlled oscillator 5 or the like, is provided with a 2nd multi-value identification device 6 identifying a multi-value of 2-series of output signals of the 4-phase detector 1 at a point of time of data conversion, a correlation device 7 taking correlation between an output signal of the 1st multi-value identification device 2 and an output signal of the 2nd multi-value identification device 6, a discrimination circuit 8 discriminating that an output level of the 2nd multi-value identification device 6 is a prescribed threshold level or over, and a switch circuit 9 adding an output of the correlation device 7 to an output of the phase error detection circuit 3 by an output of the discrimination circuit 8. |
