| 摘要 |
PURPOSE:To surely call either one of slave equipments which are capable of calling by performing the calling operation of a slave equipment by only a control channel, always monitoring the calling data from a master equipment by slave equipments which are not included in the calling operation and flexibly coping with situations even if the slave equipments are extended. CONSTITUTION:The communication data and the voice signal from a slave equipment are inputted in a high frequency amplifier circuit RX-RFAMP via an antenna and a transmission and reception switching device DPX and the amplification of the first stage is performed. Further, they are mixed with an oscillator RX-OSC signal, the amplification of the second stage is performed in an intermediate frequency amplifier circuit RX-MIX and a detection is performed. The data of a detection signal is decided in a control part, a 4-2-wire conversion is performed for voice in a hybrid transformer and the data is transmitted to a public line. Conversely, the 4-2-wire conversion is performed for the reception signal from the public line in the hybrid transformer, the signal is modulated in an oscillation circuit TX-OSC for transmission, it is amplified in a transmission side high frequency amplifier circuit TX- RFAMP and it is transmitted from the antenna to the slave equipment via the switching device DPX. As a result, even when the slave equipment is extended, either one of the slave equipments which are capable of calling through a control channel can be surely called.
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