| 摘要 |
PURPOSE:To prevent such an inconvenient case where a receiver hears the data as noises even though the data are transmitted and received via the same channel as the sound signal by making use of a spectrum inverted privacy telephone circuit. CONSTITUTION:The sound signal is transmitted and received via a spectrum inverted privacy telephone circuit. At the same time, a spectrum inverting subcarrier signal Ss is sent to the data CMND prior to the transmission of a subcarrier at the transmission side when the CMND is transmitted. Then the signal Ss is added to the data CMND and transmitted. At the reception side, a sound system is muted at reception of the signal Ss. Thus the data CMND is never heard by a user as noises even though the CMND is transmitted and received via the same channel as the sound signal. |
