| 摘要 |
A pulse position modulation pulse signal to be demodulated is sampled by a pulse detection part based on a motion clock. The motion clock is generated from a motion clock generating part so that a period of pulse precision n falls within a width of an information pulse in the signal to be demodulated. A phase relationship between the motion clock and the information pulse to be demodulated is classified into six kinds of patterns, and in case the relationship is outside the patterns, it is to be excluded as being under effect of noise. The pulse detection part gives a pulse detection signal in which the effect of the noise has been eliminated to a phase comparison part, which compares the given signal with a reproduction clock timing signal showing the timing of a reproduction clock signal generated in a clock reproduction part, then generates a control signal for controlling a phase of the clock reproduction part. Consequently, it becomes possible to lower a frequency of the motion clock for detecting a position or phase of the information pulse from the pulse position modulation pulse signal in a phase locked loop circuit.
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