| 摘要 |
PURPOSE:To extract only required information by sending plural pieces of information by one carrier frequency and identifying a code added to the head of each information at the reception side. CONSTITUTION:A voice and identification signal controlled by a channel control section 1 is subjected to FM modulation at a FM modulation section 4 at a prescribed carrier frequency. A coupling section 7 of a reception section tokes in a carrier superimposed on a telephone line, the FM demodulation section 9 sends a voice signal and an identification signal and detects the presence of the carrier signal. Then coincidence with the code of the identification signal is detected from that designated in advance by a code setting SW 12 at a code detection section 10. When both signals of the presence of carrier signal and a code coincidence signal from the FM demodulation section 9 are received, a voice control section 13 is turned on to send a voice to a voice amplifier section 14 and required voice is obtained from a speaker 15. Since only one wave is used as the carrier in this way, the installation is not increased even when much information is handled by the transmission and reception sections.
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