| 摘要 |
<P>PROBLEM TO BE SOLVED: To prevent deterioration of sound quality even if voice informed from a slave unit is amplified when a transmission state is formed, and to ensure excellent function of an echo canceller even if returning to hands-free simultaneous conversation by ending press-to-talk. <P>SOLUTION: A master unit CPU 28 performs simultaneous conversation by a simultaneous conversation circuit 26 while a press-to-talk switch 27 is not operated. While the press-to-talk switch 27 is operated, the master unit CPU 28 outputs a loudspeaker instruction signal to a slave unit 1, invalidates operation of the simultaneous conversation circuit 26 and fixes the transmission state. While receiving the loudspeaker instruction signal, a slave unit CPU 16 operates an amplifier circuit 15a included in an echo canceller 15 with a predetermined amplification factor larger than that during simultaneous conversation, and disables a microphone 13 by informing voice from a speaker 14. <P>COPYRIGHT: (C)2013,JPO&INPIT |
