专利名称：Frequency modulation method and
frequency modulated signal transmitter
发明人：Tatsumasa Yoshida申请号：US09112196申请日：19980709公开号：US06208845B1公开日：20010327
专利附图：
摘要：A frequency-modulated signal transmitter and frequency modulation methodare provided wherewith the linearity of an FM modulated signal is secured even when thelevel of frequency modulation after FM modulation is low. A level-subtraction circuit is
provided between a speech processing circuit and a frequency modulator circuit forsubtracting the signal level of the speech-processed signal Dfrom the speech processingcircuit. The level-subtraction circuit comprises a level-subtraction stage , to which thespeech-processed signal is input, that outputs a level-subtracted voice signal to the FMmodulator circuit, and an average FM noise level setting stage for setting the averagelevel (±Esn) of the FM noise generated in the frequency modulator circuit and outputtingthat average FM noise level (±Esn) to the level-subtraction stage. In the level-subtractionstage, a signal in which the signal Dand the average FM noise level (±Esn) have beenadded is obtained as a level-regulated voice signal, which level-regulated voice signal issent as the modulating signal to the FM modulator circuit. The level subtraction may beimplemented by either analog or digital processing.
申请人：OKI ELECTRIC INDUSTRY CO., LTD.
代理机构：Rabiin & Champagne, P.C.
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