| 摘要 |
PROBLEM TO BE SOLVED: To provide a modulator that can quickly set a modulation frequency to a most proper frequency within a corresponding frequency band. SOLUTION: A seek circuit 2 measures at least a frequency distribution of a strength of a received signal from a radio section 1 receiving a transmitted signal. A modulation frequency selection circuit 4 obtains an optimum modulation frequency on a frequency axis to select a frequency on the basis of the frequency distribution of the measured signal strength and gives the selected frequency to an RF modulator 5. The RF modulator 5 uses an input signal from an input source for a modulation wave to modulate a carrier and obtains a modulation output from a modulated wave with the optimum modulation frequency obtained before.
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