回音消除模块 VPMOCT128

兼容数字卡 TE420，TE405P，TE420P，TE220，TE220P
For Asterisk users who connect to the PSTN, the most common type of echo is hybrid echo - the echo introduced by the impedance mismatch between 2-wire and 4-wire telephone circuits. The echo manifests as a distorted and delayed reflection of the users voice while in conversation with an external party through the PSTN. Asterisk itself offers a range of software-based open source echo cancellation routines that are moderately effective in eliminating the hybrid mismatch echo that most Asterisk users experience.
However, there are cases in which these algorithms are not effective. To combat this, Digium introduced DSP-based echo cancellation modules for our multi-port T1/E1/J1 cards and our 24-port analog card.

Now, Digium is pleased to make available the VPMOCT032 echo cancellation module. This module, which offers 128ms (1024 taps) of echo cancellation across all of its channels and provides the same toll-quality G.168 compliant echo cancellation found in Digium's HPEC software-based commercial echo canceller. The VPMOCT032 is immune from any system CPU spikes that might otherwise affect a software-based solution.

The VPMOCT128 provides a certified carrier-grade algorithm that has been labeled a benchmark for echo cancellation. VPMOCT128 enables users to eliminate echo tails up to 128ms or 1024 taps across all 128 channels in E1 mode or 96 channels in T1/J1 modes. Further, this module takes advantage of the Octasic Voice Quality Enhancement to provide superior sound quality on all calls.

[root@bogon`]# dmesg|grep VPM

VPM450: echo cancellation for 128 channels
VPM450: hardware DTMF disabled.
VPM450: Present and operational servicing 4 span(s)