| 摘要 |
PURPOSE:To provide a demodulator for preventing the malfunction of a DC offset control circuit due to rader pulse interference relating to the demodulator used for digital radio communications provided with the DC offset control circuit for compensating signal point distortion generated in a transmission side modulation circuit and the DC component drift of a demodulation circuit. CONSTITUTION:A rader pulse detection circuit 30 generates rader pulse detection signals and outputs them to a control signal generation circuit 20 at the time of detecting rader pulses based on digital demodulation signals from an A/D converter 13. The control signal generation circuit 20 outputs '0' for fixing DC offset other than '1' for performing offset control in a positive direction and '-1' for performing DC offset control in a negative direction as DC offset detection signals and outputs '0' only when the rader pulse detection signals are inputted. Thus, during rader pulse duration, a correct value is held for the value of DC offset control signals. |
