| 摘要 |
PURPOSE:To enable an another system automatic switching function having a simple constitution by generating a control signal, which is required for switching of the constitution of a phase demodulating circuit, in a block in the succeeding stage which uses the signal obtained by the phase demodulating circuit. CONSTITUTION:When a modulated signal S1 of the B/G system is inputted to the phase demodulating circuit where the initial state corresponds to the I system, a reproduced data signal S5 is meaningless because a QPSK phase demodulating part 10 processes the signal SI as that of the I system. Though the signal S5 is inputted to a PCM decoding part 20, a synchronous detection part 21 of this part 20 brings about synchronous error to out put a synchronous error pulse S7. This pulse 97 is monitored for a certain time by a counter part 23 to discriminate chat the error is caused by the difference of setting of the demodulating part 10 in the preceding stage. Then, a setting change pulse S9 of the demodulating part 10 is outputted. The demodulating part 10 receives this pulse S9 to control the change of its own various parameters, and the phase demodulating circuit adapted to the B/G system is constituted. |
