| 摘要 |
PURPOSE:To easily automate the adjustment of a reproducing equalizer by applying the adjustment so that the difference component of an envelope between the shortest wavelength part and the longest wavelength part of a digital signal is a prescribed value. CONSTITUTION:The characteristic of a reproducing equalizer circuit 200 is adjusted so that the difference component from an operatioinal amplifier 25 is zero. In this case, the frequency of the longest wavelength part of the digital signal differs from that of the shortest wavelength part by, e.g., 4 times, and even when the signal is detected by a conventional envelope detection circuit 400, the output level of the shortest wavelength part with small energy is reduced remarkably. In applying the peaking of nearly twice to the shortest wavelength part, the level of the envelope between the shortest wavelength part and the longest wavelength part is made close to each other. That is, the envelope is detected by the circuit and the shortest wavelength part of the digital signal is extracted by deciding the values of a capacitor 15 and a coil 16 and nearly twice of peaking is applied to resistors 11, 12 and 14.
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