| 摘要 |
PURPOSE:To obtain a receiver with stable PCM code by providing an integration circuit to the pre-stage of a demodulation circuit to improve the identification performance of a signal and a noise. CONSTITUTION:An LC selection circuit 7 consists of a transistor Q2 and a tuning circuit 6 and outputs a signal in tuning with a carrier frequency received. The signal is integrated by an integration circuit 4 comprising a resistor R1 and a capacitor C1, the integrated signal is subjected to waveform shaping by a waveform shaping circuit 5 comprising a Schmitt trigger circuit or the like and the signal subjected to waveform shaping is demodulated by a demodulation circuit 3 and outputted as a PCM code. Since the signal is the PCM code and has a pulse width over a prescribed value, an output of a prescribed level or over is obtained from the integrated waveform of the signal. When the pulse width is small like a noise, the integrated waveform does not reach a prescribed level or over, then even when the signal C is waveform- shaped normally by the waveform shaping circuit 5, the integrated output of the noise N does not reach an on-level of the waveform shaping circuit 5, then the output by noises N is not obtained. |
