| 摘要 |
<p>PURPOSE:To keep the phase of a signal, which is inputted to a discriminating and reproducing circuit, at an optimum value by generating a reference pulse from a transmitted PCM signal to monitor the phase of the signal inputted to the discriminating and reproducing circuit. CONSTITUTION:The time from the leading edge of an equalized and amplified PCM signal (a) to the edge of a timing signal (b) from a logical differentiating circuit 5 is detected by a phase comparing circuit 8 to obtain a waveform (c). This waveform (c) is compared with a waveform (d) outputted from a reference pulse generating circuit by a phase comparing circuit 10, and a waveform (e) is outputted from one output of the phase comparing circuit 9 10 if the leading edge of the timing signal (b) is ahead of the center of the PCM signal (a) with respect to phase, and a waveform (f) is outputted from the other output if it is behind the center of the PCM signal (a). The output obtained in this manner is inputted to a lowpass type amplifying circuit 11 and is converted to an average voltage level to control the output pulse width of a monostable multivibrator 4.</p> |
