Method of adaptive full duplex full frequency band echo cancellation

Abstract

A method of adaptive full duplex full frequency band echo cancellation comprises the following steps of: carrying out filtration by a sub-band filter, carrying out sub-band echo cancellation by a sub-band echo canceller, carrying out weighted energy analysis and control on system signals, carrying out analysis and detection on double talk active state, carrying out coefficient updating on an echo filter, carrying out nonlinear processing on residual echo, and carrying out synthesis on signals of sub-bands. The method further comprises the step of maintaining reference signal and echo signal to be synchronous; after the nonlinear processing is carried out, noise reduction, automatic gain control and comfort noise technique can be added. Owing to adoption of the method of echo cancellation, signals are spilt into sub-bands through filtration, thus reducing correlation among signals of sub-bands, improving convergence problem of adaptive filter, reducing data process load of the system, improving processing efficiency of echo cancellation, realizing full duplex of conversation, improving frequency response of communication audio frequency, improving quality of communication and realizing echo cancellation of full frequency band response.

Description

technical field [0001] The invention relates to a communication and network system echo cancellation method, in particular to an adaptive full-duplex full-band echo cancellation method. Background technique [0002] With the popularity of audio and video conferencing systems and hands-free phones, especially the development of high-fidelity audio communication systems, and the need for virtual presence in conference systems, far-end voice signals are played through speakers so that all participants can hear them. In addition to picking up the voice of the local speaker, the local microphone also picks up the sound played from the speaker, and sends it to the remote end after being amplified. Therefore, the far-end participants will hear their own voice coming back from the other party. This phenomenon is called echo. The echo will disturb the sound effect of the meeting place, affect the thinking of the speaker, and even cause feedback howling and destroy the conference ef...

AI Technical Summary

Problems solved by technology

Its advantage is that it is simple and cheap, but its disadvantage is: due to the reason of one-way conduction, when two sides talk at the same time, the voice of one party is cut off (Cut Off) and cannot be transmitted to the other party, which affects the call effect; especially in the environment with high noise Occasionally, its mechanism cannot distinguish speech and noise signals, and cannot achieve the desired effect

However, the adaptive filter mode requires a lot of numerical calculations, and usually can only achieve narrow-band frequency response echo cancellation, such as echo cancellation for telephone communications and mobile phones; for example, Nokia's patent No. 97195672.3 is mainly aimed at telephones and mobile phones.

However, it is difficult to meet the requirements of wideband frequency response (Wide Band: 50Hz-7000Hz), ultra-wideband frequency response (Super Wide Band: 50Hz-14000Hz), and whole-band frequency response (Whole Band: 20Hz-20000Hz) of the new communication trend. Unsatisfactory; for example, ClearOne's XAP400 only has a frequency response of 200Hz-7000Hz, and Polycom's VORTEX only has a frequency response of 200Hz-10000Hz

Further, due to the influence of background noise in the echo cancellation process, the difficulty of bilateral simultaneous conversation detection and the insufficient accuracy of the adaptive filter adaptive adjustment, the effect of echo cancellation is affected, and the effect of echo cancellation or full duplex cannot be achieved.

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