| 摘要 |
PURPOSE:To follow up sufficiently the variation of phase even if the phase of a horizontal synchronizing signal is changed, by operating pulses, which are synchronized with a zero crossing detection signal of the carrier of a PSK signal, and a carrier signal to decode the PSK signal. CONSTITUTION:An input PSK signal P1 is inputted to a zero crossing detecting means A and has the waveform shaped into a binary signal by the means A, and changes from ''0'' to ''1'' and from ''1'' to ''0'' of the binary signal are detected by a zero crossing detector 2, and a pulse signal P4 shaped by a pulse shaping circuit 3 is sent to a pulse generating means B. In the means B, the signal P4 is compared with a signal P5 from a VCO6 by a phase comparator 4, and the VCO6 is controlled by a signal P7 obtained by allowing a comparison output signal P5 to pass an LPF5, and a signal having the frequency proportional to the voltage of the signal P7 is sent from the VCO6 to a 1/2 frequency divider 8 of an arithmetic means C. The frequency of the signal P5 is divided by the frequency divider 8 to obtain a signal P8, and this signal is inputted to an operator 9, and exclusive logic between this signal and the signal P1 is operated to output a signal P9. The signal P9 is inputted to a delay circuit 10 and an exclusive OR circuit 11, and a decoded signal P10 of the original signal is obtained from the circuit 11. |
