| 摘要 |
<p><P>PROBLEM TO BE SOLVED: To provide an FSK demodulation circuit wherein data are hardly misdiscriminated even in the presence of noise of a greater magnitude. <P>SOLUTION: In the FSK demodulation circuit, a polarity discrimination circuit 14 samples an FM detection signal outputted from an FM detector 13 and discriminates the polarity of the FM detection signal to convert it into a digital FM detection signal, a bit synchronizing circuit 15 detects a bit synchronizing point from the digital FM detection signal, an integral circuit 16 newly integrates the digital FM detection signal by each of preceding and succeeding bit synchronizing points on the basis of the bit synchronizing points, and a data discrimination circuit 17 compares a first threshold value with an integral signal outputted from the integral circuit 16 in a timing of the bit synchronizing point to discriminate the data. The bit synchronizing circuit 15 comprises: a correlation unit 22 taking correlation between a received signal and a known bit pattern such as a preamble; and a threshold value discrimination circuit 25 that compares an output of the correlation unit 22 with a predetermined second threshold value to obtain the bit synchronizing point. <P>COPYRIGHT: (C)2007,JPO&INPIT</p> |
