| 摘要 |
PURPOSE:To increase the frequency utilizing efficiency, by transmitting a control signal having spectrum not duplicated with the spectrum of audio signal through the synthesis with the audio signal. CONSTITUTION:An audio signal in 3.5-4kHz is transmitted to a mobile station via an input terminal 9, a synthesis circuit 10, a modulator 11, a transmitter 12 and an antenna 13. At the same time, a control signal having the spectrum not duplicated with that of the audio signal, e.g., 3.5-4kHz is inputted from a control signal input terminal 16, and it is synthesized with the audio signal at the synthesis circuit 10 to transmit it to the mobile station in the same path as the audio signal. The signal is used for a channel designation signal when the switching of frequency is required to a mobile set during call, or for a coin collecting signal when the mobile set is used as a public telephone set. |
