Modulation apparatus, modulation method, modulated wave receiving apparatus, and modulation system

摘要

Receiving levels of electric waves in a peripheral area are detected by an FM level detector 11 in an FM modulator 2. A reference frequency band in which the receiving level in which the receiving level is lowest in a plurality of reference frequency bands among a plurality of frequency bands stored in a memory 13 is selected. Date is modulated by a modulator 12 in the selected reference frequency band, and frequency band information for the reference frequency band to which a frequency of the data was modulated is superimposed on the modulated data and then the modulated data the frequency band information superimposed thereon is transmitted in the form of a digital signal. The transmitted frequency band information is received by an FM multiplex decoder in a head unit 3. An FM tuner 26 is controlled based on the frequency band information received by a system controller, and the data is fetched by attenuating signals other than those in the reference frequency band to which a frequency of the data was modulated.