| 摘要 |
PROBLEM TO BE SOLVED: To correctly detect a header, even when the state of a push-pull signal is fluctuated by various factors by generating an optimum reference signal corresponding to an actual push-pull signal in real time. SOLUTION: A peak detecting circuit 12 detects the peak value of a push-pull signal, and this peak value is inputted to a comparator 10 through an LPF 14. The output signal of the LPF 14 is applied to a comparator 10 as a positive reference signal +Ba for detecting header, which is to be compared with the push-pull signal. Meanwhile a bottom detecting circuit 13 detects the bottom value of the push-pull signal, and this bottom value is inputted to a comparator 15 through an LPF 15. The output signal of the LPF 15 is applied to a comparator 11 as a negative reference signal -Ba for detecting header which is to be compared with the push-pull signal. Thus, an optimum reference signal corresponding to the actual push-pull signal is generated in real time.
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