| 摘要 |
PURPOSE:To reduce an error ratio by detecting a voltage signal proportional to number of errors and controlling an identification phase of an identification circuit for error so as to make a differentiation signal to the identification phase zero thereby applying a clock of a same phase relation to the identification circuit. CONSTITUTION:An output of an error check use identification circuit 2 is fed to a frequency division circuit 3, in which the signal is subject to frequency division, and a low pass filter circuit 4 extracts only a low frequency component. A frequency of an output signal from the low pass filter circuit 4 is proportional to number of errors. The output signal of the low pass filter circuit 4 is inputted to a frequency voltage conversion circuit 5, in which the signal is converted into a voltage signal proportional to number of errors. A phase modulation circuit 7 applies phase modulation the clock by using a sinusoidal wave signal from an oscillator 8 as a modulation signal and gives the result to the error detection identification circuit 2. Function a synchronization detection circuit 9 applies synchronization detection to the output signal of the frequency voltage conversion circuit 5 by using the sinusoidal wave signal from the oscillator 8 as a reference signal to obtain a differentiation signal. An identification phase control circuit 6 controls an identification phase T so that the differentiation signal is zero. |
