Method and apparatus for transparently transmitting dual-tone multi-frequency signal under prepositioning echo canceller condition

Abstract

The invention relates to a method for transmitting two-tone multi-frequency signal, when there is prepositioned echo counteract device. Wherein, said method improves the EC algorithm module, to output two data groups, while one group is not treated by NLP treatment and another group is treated by NLP treatment; the data not treated by NLP is used in DTMF detection of signal sound; if the DTMF number is not detected, treating it as general voice signal and outputting the data treated by NLP to the code / decode module to be coded; if the DTMF number is detected, outputting the data not treated by NLP to the code / decode module; the invention also uses data buffer mechanism. The invention can realize normal echo counteraction to reach ideal voice quality; and based on the signal inside the DTMF band, it can eliminate echo without hurting signal; therefore, the integrated DTMF can be transmitted to the opposite.

Description

technical field [0001] The invention relates to the technical field of network communication, in particular to a method and device for transparently transmitting a dual-tone multi-frequency signal under the condition of a pre-echo canceller. Background technique [0002] In network communication systems, call quality is often affected by echoes. The EC (Echo Canceller) developed in recent years has solved this problem better. Such as figure 1 As shown, the EC algorithm module often includes an NLP (nonlinear processing) module and an AF (adaptive filter) module. The signal input to the EC algorithm module can effectively cancel the echo after AF processing, and the voice signal can improve the voice quality after NLP processing. [0003] The EC algorithm is required to meet the standard requirements of ITU-TG.168 (2002). The design of EC is mainly aimed at the echo problem of the voice signal, and the echo signal can be effectively canceled only under the premise of ensu...

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Problems solved by technology

[0006] However, this solution has the following problems: First, because the DTMF signal is treated as a general voice signal, in order to emphasize the voice quality, the EC generally starts the NLP function, which will inevitably cause damage to the signal, especially the convergence characteristics of the EC will seriously affect the DTMF Second, in the case of double-speaking, some DTMF signals may be cut off, which will seriously affect the reliability of DTMF detection and related indicators

[0008] However, this solution has the following problems: one, closing the EC will inevitably produce an echo (including the echo of the DTMF signal itself), and the echo will inevitably affect the reliability of the DTMF number receiving; the other, for general calls During the establishment process, the EC can be turned off in advance for external services, but for some services, such as PSTN (Public Switched Telephone Network) services based on FXO (External Exchange Office), VoIP (voice technology carried over IP) equipment does not know the other party In some cases, such as the second collection service, the host does not know the status of the other party, so there is no way to instruct to turn off the EC function

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