PURPOSE: To suppress deterioration of an eye aperture rate of a demodulation signal due to a frequency deviation of a carrier by forming the demodulator with an A/D converter, N-sets of delay devices whose delay time differs from each other, N-sets of detectors, N-sets of counters and a discrimination section.
CONSTITUTION: A biphase modulation signal is inputted from an input terminal 101, converted into a digital signal at an A/D converter 103, detected by delay devices 111-113 and XDRs 121-123 and outputted to counters 131-133. A discrimination section 141 selects an output of the detector in which the count is minimized for a preamble period and the result is outputted to a low pass filter 151. Even when a frequency deviation is in existence in the carrier, the delay device with a most proper delay among prepared delay devices is used to detect an input signal depending on the quantity.
OUE YUJI
HAYASHINO YUJI
UNO YASUHIRO
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