| 摘要 |
PURPOSE:To improve the talking quality by using a hook-up detection circuit for a handset and an automatic gain control circuit respectively to control the talking loss at talking and the detection loss by voice feedback. CONSTITUTION:When a B side hooks up a handset, the hook-up of the handset of a terminal device of the B side is detected by a hook-up detection circuit 14. The detection signal decreases the loss of a talking loss circuit 11 of a talking line l2 than that of loudspeaker talking by using a talking loss controller 12. The detection signal from the hook-up detection circuit 14 reduces the loss in the detection loss circuit 19 than that at loudspeaker talking. |
