MULTIPLEX SIGNAL REPRODUCING DEVICE

PURPOSE:To provide an optimum demodulation operation by providing a synchronization and asynchronization detection circuit and forcedly moving the output amplitude of all phase comparators inside a demodulator, the time constant of loop filters and the gain of loop amplifiers ira the case of asynchronization. CONSTITUTION:Only in the case of judging the asynchronization in a synchronization and asynchronization detector 7, control is performed so as to make the output of the phase comparators PD 31, 41 and 51 large and to make the time constant of the loop filters AMP small. In the case of judging synchronization, the control is performed so as to narrow a band so as to hardly receive noise other than a desired frequency. Also, by the gain of the loop amplifiers AMP, responsiveness characteristics are changed and when the gain of the amplifiers is made large, a lock range is widened and an attenuation coefficient becomes small. In such a manner, since a means for controlling the output amplitude of all the phase comparators 31, 41 and 51 inside a multiplex demodulator 6, the time constant of the loop filters 32, 42 and 52 and the gain of the loop amplifiers is provided, a PLL demodulator quickly responds from an asynchronization state to a synchronization state and optimum demodulation characteristics are obtained.