| 摘要 |
PURPOSE:To realize a 4-phase phase demodulator easily and to allow it to have both functions of carrier regeneration and automatic gain control (AGC), by using only a normal discriminator and a full-wave rectifier in combination with a simple digital circuit. CONSTITUTION:A variable gain amplifier 13 which inputs a 1F input signal is controlled by an AGC signal to output a signal with constant amplitude to the 1st signal branching circuit 1. The signal divided into two by this circuit 1 is supplied to phase detectors 2 and 3, which perform synchronous detection by using mutually orthogonal local signals form a 90 phase shifter 6 and the 2nd signal branching circuit 5. At this time, the detection outputs Dp and DQ of the phase detectors 2 and 3 are converted into binary signals by binary discriminators 7 and 8 to obtain output data as the 1st and the 2nd binary signals. The outputs Dp and DQ are rectified on the basis of the center level of the waveforms by full-wave rectifiers 14 and 15 to be converted one-level waveforms and binary discriminators 16 and 17 perform binary discrimination based upon the single-level value as a threshold value to obtain the 1st and the 2nd error signals. |
