Distorted echo inside the network on FXO channels

yeah i can see that, but how do i adjust gain per channel? any ideas on file and syntax?

Google is your friend

http://doxygen.asterisk.org/trunk/chan_dahdi.conf.html

amen to that!

If you need to do that, you should disable/uninstall the dahdi helper module or it will undo your hard work.

wonder if hardware echo cancellation is a guaranteed fix, would be simpler and more robust than going through all this fine tuning.

No, either software or hardware ec can ‘tail out’ in the time domain reflective echos, hardware with more powerful dsp’s at a monetary cost but only truly successfully after the two underlying gross causes are reduced to a minimum., again it is just applied mathematics (fast Fourier transforms) over the physics of transmission lines.

see the thing is that milliwatt test is hitting 75% of TX rate. but still in the mic it sounds horrible at times. at first i thought the phones were no good (aastra 6731i) but cisco 508g getting distorted echo tails as well, not as bad but still there… very strange that it is so viciously persistent…

Maybe it’s your hardware , is it real digium or a chinese knock-off ?

it says digium, it was sold as digium on ebay, the hardware looks genuine. but it did come from Hong Kong. i don’t have much experience with the TDM cards not much to compare with… i’ll post a picture next time i am on-site. Thanks a ton for your help Dicko, i wish you happy holidays.

http://blogs.digium.com/2011/07/29/straight-from-the-source-avoiding-clones/

i have two cards in the box one tdm400 that i had laying around and a tdm800p (advertised as such) with the digium logo on it. >>>> http://www.ebay.ca/itm/121831721915?_trksid=p2057872.m2749.l2649&ssPageName=STRK%3AMEBIDX%3AIT

it may also be the sensitivity levels of the aastra phones but internal calls are crystal clear… i added the the tx gain params to the endpoint manager (commercial) but the EPM adds quotations around values, i am not sure if this is influencing the phone’s ability to adopt what it expects as integer. i ran a couple of tests by manually changing the provisioning file, i couldn’t really tell the difference. very little documentation or literature on the 6731i outside of the aastra call manager.

i ordered the hardware EC, will keep you posted on new developments.

These are without doubt NOT Digium hardware, just spring for real stuff and I will continue to help you. If you use “real stuff” then so will Digium they have a five year warranty.

Otherwise, you are on your own dude :slight_smile:

seriously? it has the digium logo right on it! this is unbelievable how far fraudsters would go… seller registered in CA but ships from Hong Kong… i will replace them ASAP and let you know the results. How can i spot a counterfeit? i find recycling equipment a great way to save on money and reduce E-waste, how could you tell that it was counterfeit? i’m ordering another one immediately.

If it looks too good a deal to be real, it probably is, ‘Caveate Emptor’ is at least 2000 years old advice :wink:

Chances are that you can trust

At least they speak coherent Engrish.

i’m ordering from there, i didn’t think that it was that good of a deal, i thought that the older tdm800p cards (as oposed to the newer 1A8A03F) would be in the price range that i paid since they date back to 10 years ago…
I’ve worked quite a bit with IP end to end, my experience with analog is limitted, i guess i’m loosing my baby teeth a few at a time with each project. thank you for the advice

Hi
A hardware (dsp based) ec is always a better option
Having said that, and checking the ebay link posted, it suggest mg2 as echo canceler.
Have you tried oslec?
Its a far better echo canceler, (a bit tricky to get it compiled in dahdi too)
On the down side, it does use quite a few cpu resources, and if cpu resources are limited
(remember, we are talking voice here, a few milliseconds cpu stall can be heard) distortion occurs.
Is there any chance the distortion problem rises when there are more than one concurrent fxo calls?

On an entirely different solution path, getting a patton fxo box (which has an excellent hardware EC) might be a far better overall solution to what you are trying to achieve.

Regards

I am using oselc, it comes precompiled with freepbx i think. Anyway this is what is listed as ec in dahdi conf. I thought about the possibility of inadequate computing resources, I monitor CPU load with six active calls It didn’t go beyond 12%. I have a quad-core 2.7ghz Intel in this box. Strange thing is that the echo is intermittent, sometimes 6 channels active with no Echo other times only one channel with unusable sound quality.
I ordered a hardware Echo canceller from digium and another digium genuine card. I am going to try the hardware Echo canceller first and if it does not work I will replace the card. I will keep this post updated with my findings. Thank you

If oslec its listed, and you do have some kind of ec (even with issues) then its working.
A quad-core 2.7 beast is more than enough for oslec.
From experience it works fine with a single fxo card even on old atom (2008) hardware.
The hardware EC is a totally new experience though and at 6 concurrent calls in a professional environment is the way to go, since you seem to have exhausted audio level tuning options.

Echo canceling and transcoding are time critical apps at the ms level, and the human ear is very sharp at it
All other call related tasks are not.
Keeping long time tabs on cpu load (which can happen for any reason) isn’t very practical too.

Regards.

I finally got the digium hardware echo cancellation module and i installed it on the tdm800p card, how do i enable hardware echo cancellation?

If it finds i, it should be automatic

dhadi_cfg -vv