| 摘要 |
PURPOSE:To accurately perform control even when a signal point is separated from an I-axis, by selecting an exclusive OR output between the polarity signals and error signals of the channels I and Q, according to whether the signal point of a multuvalue orthogonal amplitude modulation signal is near to the I-axis, or a Q-axis, and recovering a reference carrier as the control voltage of the output phase of a voltage controlled oscillator. CONSTITUTION:A docoder 16 outputs a signal which represents whether the signal point is approached near to the I-axis, or the Q-axis, and sets it as the control signal of a selector 16. When the signal point is near to the I-axis, the output of an exclusive OR circuit 14 is selected by the selector 16, and is added on an integration circuit 17, and its integrated output becomes a control voltage for the phase control of a voltage controlled oscillator 11, thereby the phase of the reference carrier can be controlled accurately. Also, when the signal point is near to the Q-axis, the output of an exclusive OR circuit 15, that is an inversion output, is selected, and is added on the integration circuit 17, and its integrated output becomes the control voltage for the phase control of the voltage controlled oscillator 11. Therefore, the same result as a case that the position relation of the signal point is rotated by 90 deg. can be obtained, thereby, the phase of the reference carrier can be controlled accurately. |
