| 摘要 |
<p>PURPOSE:To identify the monitor tone of other channels, even with surrounding noise remarkably increased, by detecting the surrounding noise level inputted from a transmission microphone of the station itself at the reception waiting and controlling the monitor output level at the reception of other tone group through the output of detection. CONSTITUTION:When a tone signal obtained from a demmodulation circuit 1 is assigned to the station itself, it is detected at a tone squelch 4 to minimize the attenuation of an attenuation circuit 6 via a control circuit 12 and to achive an optimum receiving tone from a speaker 14. On the other hand, in monitoring other channels other than the assignment of the station itself, the said control circuit 12 controls the attenuation of the attenuation circuit 6 to a prescribed value to obtain a smaller output considerably than the station assignment channel signal tone from the speaker 14. If an acoustic noise around a receiver is increased, it is detected with a transmission microphone 7 and the attenuation of the attenuation circuit 6 is decreased with this detection output, to increase the output from the speaker 14.</p> |
