| 摘要 |
PURPOSE:To improve the detecting accuracy of an echo suppressor by using an echo canceller only for a detection section of the echo suppressor so as to eliminate or decrease an echo signal at the detection. CONSTITUTION:A switch SW302 is thrown to the position A at reception, a reception signal Rin is given to an amlifier 303 with no loss and outputted from a speaker 304. An SW311 of the transmission line side is thrown to the position A so as to give a loss of 4dB to the transmission signal from a microphone 314 so as to be set to vale of L>=GT+GR+gamma-alpha-beta, where GT, GR are gains of transmission and reception amplifiers, gamma is howling margin, and alpha and beta are the worst values of acoustic bypassing coupling. A loss of LdB is given to the reception side by the SW302, 311 at transmission and the reception side is given no loss, and a loss of L/2dB is given to the both by the SW302, 311 at double talking. A pseudo echo signal generated by an echo canceller 307 at the input side of a discriminator 308 is subtracted (310) so as to eliminate the echo signal from a discrimination input signal thereby preventing howling. |
