| 摘要 |
PURPOSE:To eliminate the necessity for transmission of a pilot signal among the slave stations and thus realize an inexpensive communication device, by securing a common use of the same channel among the slave stations and then giving feedback control to an automatic gain control circuit by the output of a mean-value wave detecting circuit for the output of a voice amplifying circuit. CONSTITUTION:A voice amplifying circuit 10 having an automatic gain control circuit is provided, and the mean value of amplitude is detected by a mean-value wave detecting circuit 11 for the output of the circuit 10 to give feedback control to the automatic gain control circuit with the detection output of the circuit 11. In such way, the signal level is equalized by means of a signal obtained by giving a wave detection to a voice signal to eliminate the necessity for transmission of a pilot signal among many slave stations. At the same time, each station is made to use the same channel in common. As a result, a direction-based automatic gain control circuit, a direction-based pilot signal and its detecting circuit plus a synthesizing circuit are disused. Thus a direction-based voice demodulating/amplifying circuit can be formed with a single voice demodulating circuit. |
