| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a demodulation method and a demodulator which does not require an analog circuit so that a structure of a FSK receiver can be simplified. <P>SOLUTION: Four counters C1 to C4 forming a count section 12 count the numbers of waves of a modulated signal at every expiration of a bit time width T at individual timings, which differ by T/4 from each other. Based on the count values, a first average value AV0 of the count values larger than a decision threshold (="9" in the figure), and a second average value AV1 of the count values smaller than the decision threshold are calculated, and a difference of the average values is designated as a determination value DAV (DAV=AV0-AV1). The counter Ci with the largest determination value DAV is specified as a counter operating at a synchronous timing with bit borders of the digital signal to be demodulated. The count values from the specified counter Ci are compared to the decision threshold to determine the signal level, and the digital signal is thereby restored. <P>COPYRIGHT: (C)2004,JPO |
