| 摘要 |
radio communication systems including cellular ones. SUBSTANCE: cellular telephone set has antenna, four band filters, receive and transmit circuits, two heterodynes, two mixers, heterodyne frequency selector switch. Method for selecting intermediate transmission frequency includes search for medium carrier frequency during wobbling intervals of first- and second-band radio frequency, calculation of difference between medium transmission carrier frequency of first frequency band and medium transmission carrier frequency of second frequency band, subtraction of first-band medium transmission carrier frequency and second-band radio frequency from second-band medium carrier frequency during heterodyne frequency wobbling interval to determine intermediate frequency of transmission signal and to add the latter to frequencies in the beginning and end of radio frequency band. EFFECT: reduced space requirement and cost, provision for automatic actuation of cellular telephone system. 5 cl, 3 dwg
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