| 摘要 |
PURPOSE: To prevent an abnormal demodulation by eliminating the indeterminacy of the pull-in phase in the reproduction of a carrier wave. CONSTITUTION: A reception modulation signal 101 is branched into two in a branching circuit 1 and the branched signals are inputted in phase detectors 2 and 3. An orthogonal phase detection is performed for the reception modulation signal 101 by the carrier wave signal outputted via a quadruple phase shift modulator 16 by the phase synchronizing system for reproduction of a carrier wave in the phase detectors 2 and 3. At this time, the outputs of the demodulation signals of a P channel and a Q channel are delivered to a pull-in phase discrimination circuit 7 via A-D converters 4 and 5, and a pull-in phase is detected. A prescribed phase shift is imparted to the output phase of the voltage control oscillator 14 included in a phase synchronizing system via the decision result by this detection output, a phase supplement is quickly performed and the state enters a normal demodulation state. |
