Questions on hardware or software-based echo cancellation

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Asterisk Users 3 Comments


I’m having some questions related to echo cancellation configuration
on a Digium board enabled systems (B410P, TE420, TE420B, ….) for
cases when a hardware ech canceller is present or not.

I read in TEXXX manual that when setting echocancel=yes in
chan_dahdi.conf on a VPMOCT64-equiped system, 128ms hardware echo
cancellation was enabled.

1. I’m correct thinking that it is then impossible to switch from
hardware to software echo can without removing the VPMOCT64 module
itself ?
2. Does the same also apply to HA8 and its VPMOCT032 module ?
3. Are the only options for OSLEC configuration the echocancel=128 or
echocancel=256 values in chan_dahdi.conf ?
4. How could be compared user experience with oslec/256, mg2/256,
mg2/1024 on a HA8 without hardware module ? Which would you recommend


3 thoughts on - Questions on hardware or software-based echo cancellation

  • With DAHDI 2.6 (and possibly 2.5), it is possible to override the
    configuration and apply a software echo canceller to a channel even if
    it has a hardware one. With prior versions, yes, the echo cancellation
    module would have to be physically removed (or disabled using a
    parameter to the kernel module).

  • 2012/1/12, Kevin P. Fleming :

    Then, maybe a line mentioning that in the next User Manual edition
    would be perfect.
    Thanks for replying.

  • Sure, but you have to understand that the user manuals for our board
    products are typically only updated when the board itself gets changed;
    we don’t actually deliver DAHDI with the boards, and
    installation/configuration instructions for DAHDI are primarily included
    in the manual for user convenience. Users should be aware that they
    could easily be out of date, and not include all options that are
    currently offered (although if the user manual’s instructions become
    incorrect, we’ll update the manual). Regardless, I’ll mention this to
    the people who manage those products. Thanks!