| 摘要 |
PURPOSE:To attain secure data demodulation by setting an appropriate threshold signal so as to obtain correlation pulses when the output of a correlator with fluctuation in the level of a reception signal. CONSTITUTION:The device is provided with a first peak value detection circuit 18 detecting the peak value (j) of a positive polarity correlation spike, a second peak value detection circuit 19 detecting the peak value (k) of a negative polarity correlation spike, a comparison circuit 10 comparing the peak values (j) and (k), a selection circuit 11 selecting the peak values (j) and (k) by the output (l) of the comparison circuit 10, and threshold setting circuits 12 and 13 generating thresholds Q and R based on the peak values selected by the selection circuit 11. Comparison circuits 14 and 15 compare the output (c) of an A/D converter 2 and the output S of an inversion circuit 3 with the threshold signals Q and R, and the correlation pulses (n) and (o) corresponding to a correlation spike (a) can be obtained. Thus, accurate data demodulation is attained with respect to fluctuation in the level of the output of the correlator 1. |
