| 摘要 |
PURPOSE:To decrease the time required for suppressing phase distortion by detecting the phase distortion of a pulse waveform generated on a transmission line and connecting/disconnecting a fixed phase device to a phase control circuit to suppress the residual phase distortion by means of automatic continuous phase control. CONSTITUTION:The pulse waveform subjected to phase distortion on a transmission line is demodulated (DEM) and the phase distortion is detected by a 90 deg. phase shift detecting circuit SWDET from the waveform distortion of the demodulated signal. Contacts 2, 4 of a phase switching circuit SW are connected normally, but when the amplitude of the waveform distortion of the demodulation signal is larger than a prescribed value, the circuit SWDET has a large phase and it is discriminated that the phase is retarded, then contacts 1, 4 are connected to remove the fixed 90 deg. phase shifter 90 deg. PS and when it is discriminated that the phase is advanced, contacts 3, 4 are connected to connect the fixed 90 deg. phase shifter 90 deg. PS. A large phase shift is corrected in this way and the residual phase distortion is corrected by controlling the phase of the carrier of the demodulator DEM by means of the automatic continuous phase control comprising an A/D converter, a shift register SR, a phase distortion detecting section DET, a PLL circuit and voltage controlled variable phase shifter CAPC. |
