| 摘要 |
PROBLEM TO BE SOLVED: To determine a symbol accurately by avoiding such a situation as the determination precision of a symbol deteriorates until correction is completed because a trouble occurs in exact determination owing to deviation of a threshold by DC offset or the like resulting from the frequency difference between a transmitter and a receiver in determination based on comparison of the voltage level of a detection signal and the threshold when a symbol is determined from a reception signal of FSK system, and phase correction of a clock signal is required because the extraction timing of voltage level is detected in synchronism with the clock signal. SOLUTION: Differential value of a detection signal is detected (S27). A differential value having a maximum absolute value in one symbol period is detected (S28, S29). This symbol is determined (S30, S31) by calculating the change direction and the number of steps of a voltage level for an old symbol (a symbol of previous determination result) based on the differential value having a maximum absolute value and the old symbol. COPYRIGHT: (C)2009,JPO&INPIT
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