| 摘要 |
PURPOSE:To make it difficult to be affected by noise and reduce the circuit shape by detecting the rise point and the fall point of a binary FSK demodulated signal restored to a square wave to generate pulses and operating OR between them. CONSTITUTION:The binary FSN demodulated signal is restored to a square signal by a comparator 1, and the output of a rise point detecting circuit 2 is as shown in a figure (b) if this circuit 2 is so constituted that a pulse is generated at the rise point of the square signal. The constant of a used element is properly selected to set the width of the pulse to a half period of the demodulated signal. The output of a fall poin detecting circuit 3, which is so constituted that a pulse is generated at the fall point of the square signal, is as shown in a figure (c). When pulses shown in figures (b) and (c) are inputted to an OR circuit 4, a pulse whose width is a half period is generated at each time of inversion of the demodulated signal as shown in a figure (d). Consequently, since a double frequency component is generated if an input signal is random, the signal is allowed to pass a band-pass filter 5, thereby extracting a clock component. |
