| 摘要 |
PURPOSE:To ensure the correct reproduction for both main and subordinate data signals despite of an inconvenient pull-in state in phase by using the receiving subordinate data signal and the output of a sull-in phase discriminating means to reproduce a receiving main data signal from a demodulating signal. CONSTITUTION:An input signal is fed to a phase locking demodulator 1 and turned into demodulating signals P and Q which are orthogonal to each other. These signals P and Q are 2-multiplied by a multiplier 4 and supplied to a disscriminator 6 via an LPF5 to be reduced to a subordinate data signal. While the signals P and Q of the output of the demodulator 1 are fed to an adder 2 and a subtractor 3 and shifted in phase. Now if the output of the adder 2 is selected by an analog switch 9, the input of an analog switch 10 is reduced to the output of the adder 2 and the subtractor 3 respectively. When the switch 10 is controlled by the output of the discriminator 6, a main data signal is reproduced at the output of the switch 10. On the other hand, a pull-in phase discriminator 7 uses a frame signal contained in the subordinate data signal to discriminate the pull-in state in phase of the demodulator 1. If an inconvenient pull-in state is decided, the output of an adverse polarity 8 is selected by the switch 9 for the adder 2. |
