PROBLEM TO BE SOLVED: To reduce the current consumption by applying control to the demodulation and modulation circuits in a way that supply of a clock signal to a detection circuit is stopped until a succeeding symbol time begins after the detection of a prescribed carrier pulse in existence in a symbol time of a PPM signal through the use of the clock signal whose frequency is twice or over a transmission rate of the PPM signal. ;SOLUTION: In the circuit demodulating a modulation signal modulated by the 4-value PPM system into original data, any of 4 tips forming a symbol time in the modulated signal is set to 'H'. The position of the carrier pulse is detected by using a clock signal whose frequency is twice or over a transmission rate. After the position is detected, supply of the clock signal to the internal circuit is stopped. In this circuit, since the transmission is 4 Mbps, the frequency of a clock signal for discriminating a modulation signal level is 8 MHz that is equivalent to twice the transmission rate.;COPYRIGHT: (C)1999,JPO
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