| 摘要 |
PURPOSE:To discriminate a modulation wave with less frequency shift at a high frequency. CONSTITUTION:A line input 30 is supplied to a comparator, from which a square wave 31 is obtained and a differentiation circuit 15 extracts a differentiation outputs 32 representing a leading point and a trailing point of the square wave and supplies them to a CPU 16. A pulse width measurement counter 161 of the CPU measures a pulse width of the differentiation output sequentially to give pulse width data to a reception pulse output counter 163 and a conversion table 162. The counter 163 outputs an output 33 of the same waveform as the square wave 31 and the conversion table 162 outputs a delay width in response to a difference between a relevant pulse width and a half of the center frequency period with respect to each of the leading point and the trailing point of the reception output 33. A reception pulse output counter 164 outputs the reception delay output 34 subject to delay width delay. Both the waves 33,34 are given to an EXOR gate 9 and applies smoothing and shaping to obtain reception data RD. |
