| 摘要 |
PURPOSE:To effectively use a transmission band, by providing a filter means band-limiting each channel at audio band for a plurality of channels respectively and multiplexing the system with a narrow frequency interval for each channel at channel conversion. CONSTITUTION:Channels CH1-CH4 are provided with band pass filters 1-4 filtering a linger signal frequency, high-pass filters 29-32 of communication current of audio band and low-pass filters 5-8. An audio frequency signal band- limited for the channels CH1-CH4 is modulated by using a carrier oscillator 25 and modulators 9-12, and a modulated wave outputted from the modulators 9- 12 is filtered by using band pass filters 13-16. Each filtered output from the filters 13-16 is modulated by using carrier oscillators 33-36 and modulators 17-20 and synthesized with the modulated wave and filtered with a band pass filter 26. |
