Echo removing apparatus

Details Echo removing apparatus Echo removing apparatus

1996-03-05

1998-04-07

Zele, Krista

Telephonic communications

Subscriber line or transmission line interface

Network interface device

379390, 379406, 381 93, H04M 900

Patent

active

057374090

ABSTRACT:
An echo removing apparatus for reducing the echo caused by sound generated turning from a speaker round to a microphone of a small-sized sound generated communication terminal, such as a portable telephone. A speaker output signal X(k), sent from a terminal 11 to a speaker 12, is sent to a smoothed power value calculation circuit 21 of a tap coefficient estimation circuit 21 where a smoothed input signal power value Px(k), which is a smoothed version of the square sum values, is found and sent to a tap coefficient updating circuit 22. Using the smoothed input signal power value Px(k), the tap coefficient updating circuit 22 updates tap coefficients of a filter 15. The filter 15 filters the speaker output signal X(k) to output a pseudo echo signal which is sent to a subtractor 14 where it is subtracted from a microphone input signal collected by a microphone 13. The filter tap coefficients may be prohibited form being fluctuated and echo removing characteristics of the echo removing apparatus may be stabilized without increasing the processing volume for tap coefficient estimation.

REFERENCES:
patent: 5408530 (1995-04-01), Makino et al.
patent: 5463618 (1995-10-01), Furukawa et al.
patent: 5477534 (1995-12-01), Kusano
patent: 5572621 (1996-11-01), Martin

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