| 摘要 |
PURPOSE:To attain SS synchronization acquisition and SS synchronization holding even against a weak input level or remarkably fluctuation of a received electric field strength. CONSTITUTION:The demodulator is provided with an inverse spread demodulation means 13 that receives an SS modulation wave resulting from a polyphase PSK signal obtained by adding plural information signals with orthogonal carrier modulation by a prescribed carrier and further subject to spread modulation by using a spread code and that multiplies the spread code with the SS modulation wave, a band pass filter 15 sending the polyphase PSK signal with the obtained inverse spread demodulation signal, a carrier recovery circuit 38 recovering the carrier based on the polyphase PSK signal, primary demodulation means 30,31 multiplying the recovered carrier and the polyphase PSK signal to implement PSK demodulation to obtain plural demodulation signals, a level identification circuit 17 identifying a noise level in an error signal in a phase locked loop included in the carrier recovery circuit 38 to generate a synchronization acquisition signal, and a synchronization acquisition means 39 or the like implementing synchronization acquisition with the obtained synchronization acquisition signal. |
