| 摘要 |
PROBLEM TO BE SOLVED: To search technology capable of performing carrier offset in short time. SOLUTION: A carrier offset detection circuit is provided, which is provided in a demodulation circuit which demodulates a received signal to which FSK (Frequency Shift Keying) modulation is performed, and detects offset of carrier frequencies on the receiving side and the transmitting side. A zero cross detection part receives a digital base band signal representing a level of frequency shift of the received signal on the basis of the carrier frequency on the receiving side, and detects a zero cross point between the base band signal and a base band signal delayed for one symbol, which is generated in a period of preamble. The carrier offset detection circuit sets a value of the base band signal in timing of detected zero cross as an offset value of the carrier frequencies. COPYRIGHT: (C)2009,JPO&INPIT
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