Loudspeaker telephone set

Abstract

Abstract PURPOSE:To prevent the echo cancelling from being affected even if many distortion is caused from a speaker amplifier due to the increase in an input signal level by providing a means obtaining an input signal of a pseudo echo generating circuit from an output signal of the speaker amplifier. CONSTITUTION:In a loudspeaker telephone set provided with an echo canceller cancelling an echo signal produced from an acoustic signal outputted from a speaker from the acoustic signal inputted to a microphone, a pseudo echo generating circuit 4 is inserted between the output side of a speaker amplifier 2 and a substraction circuit 5 and the input signal of the circuit 4 is obtained from the output signal of the speaker amplifier 2. Since the pseudo echo is generated from the output of the speaker amplifier 2 having the possibility producing the largest nonlinear distortion in this way, even if the input signal level is increased and much distortion is caused by the speaker amplifier, the sending of noise due to the distortion is avoided to the opposite party without giving effect on the echo cancelling.

Inventors

• 👤 Hisashi Fujisaki
• 👤 久司 藤崎
• 👤 Shigeaki Ashida
• 👤 芦田　茂昭

Bibliographic Details