| 摘要 |
PURPOSE:To obtain a high-quality reproduced carrier wave without increasing the jitter nor causing any step-out although the noise or disturbance, by controlling a voltage controlling oscillator with the output that is obtained by giving a sample holding to the control signal with the frame signal. CONSTITUTION:The 16QAM signal supplied from the input terminal 1 receives a synchronous wave detection by the phase detectors 2 and 3 and based on the output of the voltage controlling oscillator 18 plus the output obtained by giving a 90 deg.-phase shift to the above-mentioned output. Thus the base band signal is obtained. An arithmetic process is given to the base band signal plus the 1st path signals 20 and 21 that are discriminated by the 4-value discriminators 10 and 11 to obtain the voltage proportional to sin4thetae (thetae: phase error). This voltage is fed back to the oscillator 18 via a sample holding circuit 16. On the other hand, the frame signal is extracted out of the signals 20 and 21 through the frame synchronous circuit 13, and the circuit 16 is controlled by the frame signal or one output in the asynchronous state and sent from the synchronous/asynchronous deciding circuit 14. |
