| 摘要 |
PURPOSE:To obtain a carrier wave reproducing circuit of simple constitution, by executing a logical operation between A/D converting outputs of 2 phase detector outputs for orthogonally detecting an orthogonal amplitude modulating signal, and obtaining a control signal of a voltage controlling oscillator. CONSTITUTION:An input signal (16QAM signal) is detected by phase detectors 2, 3, and outputs S1, S2 are obtained. The outputs S1, S2 are A/D-converted to signals of (X1, X2, X3), (Y1, Y2, Y3) by A/D converters 5, 6. In this case, X3 or Y3 shows a phase shift of the signal, and X1 or Y1 shows a quadrant in which the signal is positioned. Accordingly, when the signals X3, Y3 are brought to EX-OR operation by making them pass through an EX-OR circuit 7, ''1'' appears as its output in case of phase rotation in the direction as indicated with an arrow in the figure, and ''0'' appears as its output in case of its reverse direction. An output of the EX-OR circuit 7 controls a voltage controlling oscillator 9 through an LPF8. |
