| 摘要 |
PROBLEM TO BE SOLVED: To provide a demodulation system which solves the problems of a conventional technique and can cope even with demodulation processing of different modulation system and band. SOLUTION: This demodulation processing system is has a means which calculates a sampling frequency according to the center frequencies and the bandwidth information of HF, VHF and UHF band received signals, controls a PLL oscillator 6 or the oscillator 6 and the number of frequency divisions of a variable frequency divider performing frequency division of an output of the oscillator and converts an analog signal into a digital signal according to a sampling frequency that is lower than a double highest frequency inputted to an A/D converter 5 by controlling the sampling frequency of the converter 5, and a means which calculates a carrier frequency that is lower than the center frequency of a signal inputted to the converter 5 according to the sampling frequency and performs demodulation processing 13 by the carrier of digital signal processing subjected to frequency conversion.
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