[asterisk-users] Questions on hardware or software-based echo cancellation

[Kevin P. Fleming]

On 01/13/2012 02:12 AM, Olivier wrote:
> 2012/1/12, Kevin P. Fleming<kpfleming at digium.com>:
>> On 01/12/2012 06:39 AM, Olivier wrote:
>>> Hi,
>>>
>>> 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 ?
>>
>> 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).
>
> Then, maybe a line mentioning that in the next User Manual edition
> would be perfect.

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could easily be out of date, and not include all options that are 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!

-- 
Kevin P. Fleming
Digium, Inc. | Director of Software Technologies
Jabber: kfleming at digium.com | SIP: kpfleming at digium.com | Skype: kpfleming
445 Jan Davis Drive NW - Huntsville, AL 35806 - USA
Check us out at www.digium.com & www.asterisk.org