| 摘要 |
PURPOSE:To improve radio transmission quality independently of geographical position of each mobile body by selecting in advance an optimum operating frequencies respectively between a fixed station and plural mobile stations and presetting the transmission/reception frequency of a transmitter, and a receiver provided respectively to a transmission station and a reception station of a fixed station side to the said operating frequency. CONSTITUTION:An automatic line changeover devices 3 and 4 which change over private lines 5 and 6 to a transmission station and a reception station to a designated channel in f1-fn according to rules set between a fixed station and mobile stations are used for transmission and reception respectively. A transmitter TX1 transmits a frequency f1, a TX2 transmits a frequency f2 and a TXn transmits a frequency fn and a transmission wave for an object mobile station is irradiated automatically from an antenna when the transmission automatic line changeover device 3 of a central station has only to select a private line. When a reception signal received, demodulated with a voice frequency is transmitted to the reception automatic line changeover device 4 in the central station via a line A, the device 4 selects the channel corresponding to the mobile station and gives an output from a line B to a signal converter 2.
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