| 摘要 |
PURPOSE:To attain correct demodulation even when the transmission speed of a modulation signal and the modulation frequency are close to each other by sampling twice a phase consecutive FSK modulation signal subject to waveform shaping during one bit and taking an exclusive OR to the two values. CONSTITUTION:The phase consecutive FSK modulation signal subject to waveform shaping is inputted from a terminal 7 and sampled (8) by using an output pulse of a timer 11. A shift register 9 shifts an output of the sampling circuit 8 for one bit's share by using the output pulse of the timer 11. The sampling circuit 8 and the shift register 9 are activated at the leading of the pulse from the timer 11 and the output of the timer 11 is synchronized with the input signal. The output of the sampling circuit 8 and the shift register 9 is inputted to an exclusive OR circuit 10. Thus, this is equivalent to the sampling 2 times during 1 bit, and correct demodulation is executed even when the transmission speed (bit rate) of the modulation signal and the modulation frequency corresponding to the logical output ''0'', ''1'' are closed to each other. |
