[Re] Re: [Asterisk-Users] Echo canceller on TE406 & Asterisk

[Cyril VELTER]

kpfleming at digium.com wrote :
>
> Boris Bakchiev wrote:
> 
> > Could echo cancellation on PBX conflict with VPM module and create the
> > "warping babble" sound that my users are reporting?
> 
> I don't think so, but anything is possible :-)
> 
> > Do echocancelwhenbridged and echotraining do anything when VPM module is
> > used? Should I be using them?
> 
> No, they have no effect when VPM echo cancellation is in effect, but 
> they also don't hurt anything.


	I've also some problem with a TE411P. And am in contact with Digium support 
about it (Chris Hozian) and while I tend to agree with you on the fact that 
echocancel should be at yes, support told me to disable it to get echocan. This 
is a quote of one of their messages :


"Since you have the hardware echo cancellation module you will want to
have the software echo cancellation options in your zapata.conf disabled:

echocancel=no
echotraining=no
echocancelwhenbridged=no

Please verify that your rxgain and txgain are set to 0 in your zapata.conf."



	I've done several test with a line with consistent echo :

	IaxClient base softphone or GXP2000 (ALaw) -> Asterisk -> TE411P -> (ULaw) 
Rhino Channel Bank -> Analog extension

	With VPM Support disabled in zaptel and echocancel=no => Quite loud echo
	With VPM Support disabled in zaptel and echocancel=yes => Echo in the first 
second and then nearly no echo. The software echo canceler do its job.
	With VPM Support enabled in zaptel and echocancel=no => Quite loud echo
	With VPM Support enabled in zaptel and echocancel=yes => Quite loud echo. It 
has a tendancy to reduce over time but stay at a quite high level (not 
acceptable at all in production). There also some audio artifacts not present 
when echacanel is disabled which migh indicate that something happen on the 
signal.



	Would be nice to solve this, for now The sofware echocan is doing quite a nice 
job, but it's a bit frustrating to have this piece of hardware unused.


	Cyril