[Asterisk-Users] Echo -when software doesn't cut it.

[dialtone9 at phreaker.net]

Kindly post it back here when you find something, IF you find something, as 
Ive been fighting the exact same problem here, and followed the same route 
you guys did. Ive given up at this point. At this juncture, Im convinced 
the telco is sending it out intentionally....or space aliens are bringing 
it...its only on the PSTN lines...Versleazon in my case....because if this 
problem isn't curable, then asterisk is dead in the water as far as Im 
concerned.
I simply can not use a system that sounds like people talking are in a 
tunnel. At this point, this is the only "point of failure" that kills the 
whole idea of using this as a "real" switch.

Now, as far as echo cancellation, Ive looked as some of the docs, like the 
motorola paper,
http://e-www.motorola.com/files/dsp/doc/white_paper/PTECANWP.pdf and some 
purely theoretical stuff, but their math is beyond me.
  Unless someone has developed a whizz-bang improvement over the stuff I 
read, the point of transiting from a two wire to a 4 wire model will always 
cause echo, period, done, abandon the idea, lets go do something else. The 
limiting factor I see, is our software echo handling doesn't have the 
computational horsepower attached (no cpu, or stealing cpu cycles from main 
cpu) to be effective. Does this mean another piece of expensive hardware? 
Dedicated proprietary chips like the Moto? I'm thinking so.

SO, This is it, critical point of failure...cant go on, at least I cant use 
it. Yes, * does a lot of other stuff just fine, but this is the immovable 
object, at least for me.. This is something it must do and do well or its 
over.
Ive been holding my breath, hoping something pops up, but it hasn't.



At 09:21 7/1/2004, you wrote:
> > Over the last couple weeks I've tried everything I could get my hands on
> > in an attempt to get rid of my echo problems. Using a CVS checkout of
> > just yesterday, I've tried every echo cancellation routine in zconfig.h
> > (including Mark2 w/Aggressive) , as well as the echotraining=800
> > mentioned on this list just last week.
> >
> > While some things worked better then others, I would consider none
> > acceptable solutions in my situation. Playing with rx/tx gain values
> > just seemed to quiet the voice down and along with that the echo
> > happened to be less noticeable. I could almost get the echo to disappear
> > with a low enough rx/tx gain, but then the voice could barely be heard,
> > or DTMF tones stopped working.
> >
> > So whats the next step?
> >
> > I only get echo when dialing over the PSTN. Using Nufone to dial a PSTN
> > number results in absolutely zero echo. Do I put in a request for a
> > Telco technician to come out and take a look at the lines?
> >
> > One page on the Wiki says:
> >
> > "Most of the telco's have technicians with the equipment necessary to
> > help find the problem if the problem really is their outside plant.
> > However, getting to that person can be a real challenge."
> >
> > Any suggestions on ways to overcome the challenge of getting the right
> > technician on the phone?
>
>Mike,
>
>Contact me off list and let's see if we can isolate the issue. Can't
>tell from the words you've used what steps you've gone through to date.
>
>Rich
>
>
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