| 摘要 |
PURPOSE:To stop circuit operation in case of the generation of a noise and to prevent malfunction by demodulating an input signal, generated by frequency shift keying (FSK), as two 1 and 0-tone separate systems, and comparing the demodulation levels of the both with each other. CONSTITUTION:An FSK signal is demodulated by[1]and[0]demodulators 2 and 3 into a[1]and a[0]signal. Those outputs are compared with each other by a comparator 6 to regenerate a PCM signal, which is supplied to a processing circuit 10. The outputs of said demodulators 2 and 3 are inputted to a level difference detecting circuit 11, which when the level difference between both the inputs exceeds a certain value, supplies a signal to a processing circuit 10. The processing circuit 10 performs processing operation only when there is the signal from the circuit 11. |
