| 摘要 |
A hands-free telephone for use on a vehicle and having a handset incorporating a radio section therein and a hands-free adapter incorporating a hands-free telephone unit therein. To eliminate howling, this kind of telephone generally needs two variable attenuators, or variolossers, each for changing the level of respective one of a receive and a transmit signal to be applied to a speaker of a hands-free telephone unit and a radio section, respectively, so as to maintain the two levels in a predetermined relation, and a variable resistor for adjusting the volume of voice to be outputted by the speaker. In the present invention, the variable resistor is implemented by a variable resistor which adjusts the level of a receive signal to be applied to a receiver installed in the radio section. This receive signal is controlled in level by a third variable attenuator simultaneously with the above-mentioned variable attenuators. |
