| 摘要 |
PROBLEM TO BE SOLVED: To accurately conduct a submerged communication by ultrasonic waves even under a Doppler effect and the effect of noises. SOLUTION: A receiver 1 receives a synchronous signal as a linear FM signal, a reference signal as a known sine-wave signal of a frequency and an information signal as the sine-wave signal of the frequency corresponding to the value of a transmission information. A matched filter 24 carries out a complex matched filter processing corresponding to the synchronous signal to an input signal, and outputs an absolute-value system D [n]. A gate generator 25 uses a time when the maximum value of D [n] as a synchronous-signal receiving time, and generates gates for the reference signal and the information signal while using the time as a reference. A frequency estimator 27 carries out a discrete Fourier transform to the input signals in the gates, and estimates the frequency corresponding to the maximum value of a frequency spectrum as the frequencies of the reference signal and the information signal. A frequency corrector 28 corrects the estimated frequency of the information signal on the basis of the known frequency of the reference signal and the estimated frequency. COPYRIGHT: (C)2006,JPO&NCIPI
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