| 摘要 |
PURPOSE:To obtain always a demodulated signal having a correct sign polarity in the reception side by discriminating whether the sign polarity of the demodulated signal is correct or not in the reception side and inverting the sign polarity if it is not correct. CONSTITUTION:In a receiving part 7, comparison signals 19 and 24 are adjusted to the same level and the same phase and are inputted to a differential amplifier 20. If a demodulation output 22 has a correct sign polarity, comparison signals 19 and 24 are cancelled and an output 26 of the differential amplifier 20 is about zero; but if it has the opposite sign polarity, waveforms of comparison signals 19 and 24 are emphasized and the large output 26 is generated in the differential amplifier 20. The output 26 of the differential amplifier 20 is inputted to a sign polarity discriminating circuit 27; and if it is discriminated that its level exceeds a reference value, a control signal 32 is sent from a sign polarity discriminating circuit 27 to a sign inverting circuit 25 to invert the sign polarity of the demodulation output 22. If it is discriminated that the level is lower than the reference value, the demodulation output 22 is judged to have the correct sign polarity, and the sign inverting circuit 25 outputs the demodulation output 22 with the sign polarity as it is. |
