To select valid/invalid pull-in whether or not a device is in a steady- state communication state or in a training state or the like in the device whose level adjustment conducts pull-in in the case that level fluctuation of a received signal is a prescribed range or over.
A band-pass filter 4 extracts a Nyquist tone signal from an input signal and a power calculation section 5 discriminates a level of the extracted tone signal. A line equalizer control section 7 controls a line equalizer 1 based on a level of the calculated tone signal. On the other hand, a level adjustment circuit pull-in section 6 forcibly pull-in the line equalizer control section 7 when a level of the tone signal is fluctuated in excess of a prescribed range. However, when the control section 6 discriminates that the device is in a steady-state communication state based on the level of the tone signal, pull-in in the line equalizer control section 7 is invalidated.
MIYAZAWA HIDEO
KAWADA NOBORU
ASAHINA TAKESHI
OGAWA TORU
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