[Asterisk-Users] Echo problem

[Neil and Fiona]

I haven't gone all the way back to the original poster, but I noticed
mention of a TDM400 in a couple of places.

If you are not in North America, you need to pass an option to the wctdm
driver when it loads to set it in the right mode. Default is FCC mode.

This leaves the card with an impedance mismatch in Australia for
example. When loaded like that, no amount of tweaking gain and echo
cancel would get it right. Getting it to load "AUSTRALIA" mode fixed our
problem nicely.

I added the bit at the bottom of the Wiki a while ago

http://www.voip-info.org/wiki-TDM400P



On Wed, 2005-06-08 at 17:51 -0700, Kris Boutilier wrote:
> > -----Original Message-----
> > From: Andrew Kohlsmith [mailto:akohlsmith-asterisk at benshaw.com]
> > Sent: Wednesday, June 08, 2005 11:27 AM
> > To: asterisk-users at lists.digium.com
> > Subject: Re: [Asterisk-Users] Echo problem
> > 
> > 
> > On Wednesday 08 June 2005 13:37, Martin Roy wrote:
> > > rxgain= I tried from -8.0 to 10.0
> > > txgain = I tried from -8.0 to 10.0
> > 
> > Unless you are making measurements and actually analyzing the 
> > results you're only stabbing in the dark playing with these things.
> > 
> {clip}
> > 
> > Take a read here.  I reference this document continuously:
> > 
> > http://lists.digium.com/pipermail/asterisk-users/2004-November/071301.html
> > 
> > Yes, it's work and yes, you may have some trouble doing it/locating the 
> > numbers for milliwatt and quiet term but you know what, this is engineering 
> > and this is how to do it correctly.  Everything else is just 
> > pissing around hoping for a solution rather than making educated guesses and 
> > anlyzing the results.
> > 
> 
> You may also wish to review http://lists.digium.com/pipermail/asterisk-users/2005-March/096426.html which attempts to explain the causal relationship between gain and echo - ie. Nework Loss Planning. A neutral configuration may not be the optimal soloution in all cases.
> 
> Kris Boutilier
> Information Systems Coordinator
> Sunshine Coast Regional District
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