| 摘要 |
PURPOSE:To prevent the deterioration of the frequency utilization efficiency by correcting an oscillation frequency of a local oscillator to a prescribed frequency, based on a center frequency of a band pass filter which outputs a signal exceeding a prescribed value. CONSTITUTION:At the time of demodulating a spread spectrum signal, a signal of a prescribed frequency is extracted from a reverse diffusion signal or a signal obtained by converting the reverse-spread signal to a necessary frequency by plural band pass filters 21, 25 and 28, F1-F101 whose center frequencies are different from each other, and also, whose passing band width is equal to each other. Subsequently, synchronization of the PN sequence between transmission and reception which detects a fact that the maximum value of an output signal level of each band pass filter exceeds a prescribed value is taken, and also, based on the center frequency of the band pass filter which outputs the signal exceeding this prescribed value, an oscillation frequency of a local oscillator 17 provided on a demodulating equipment W is corrected to a prescribed frequency. in such a way, original information data can be obtained without avoiding the frequency utilization efficiency. |
