| 摘要 |
PURPOSE:To obtain a reference carrier wave of a short acquisition time and little phase jitter, by extracting carrier wave components in the part of a preword without elimination of phase modulation components, in demodulation of burst offset PSK modulation communication. CONSTITUTION:The receiving signal of the offset PSK modulation signal is supplied to control signal detecting circuit 10, delay line 2, and four-phase phase detecting circuit 8, and it is detected by circuit 10 whether the receiving signal is preword part or an information word part, and the first or the second control signal is generated according to this detection result. Though the output of delay line 2 is supplied to carrier wave components extracting circuit 7 through phase shifter 4 and controlled four-phase phase modulating circuit 3, circuit 3 outputs the input signal to extracting circuit 7 by the first control signal and modulates the input signal inversely by the second control signal according to the output obtained by sampling and discriminating and reproducing the demodulation output from circuit 8 by the timing signal from clock timing extracting circuit 11, and this inversely modulated output is supplied to circuit 7. It is detected in circuit 7 on a basis of the extracted reference carrier wave. |
