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

[Chris Albertson]

--- "dialtone9 at phreaker.net" <dialtone9 at phreaker.net> wrote:
> 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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=====
Chris Albertson
  Home:   310-376-1029  chrisalbertson90278 at yahoo.com
  Cell:   310-990-7550
  Office: 310-336-5189  Christopher.J.Albertson at aero.org
  KG6OMK


		
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