[Asterisk-Users] Echo PSTN Asterisk@Home 2.0 Digium TDM11B & DSL

[David K Parker]

Oh, forgot... from what I understand, my problem was due to an impedence
mismatch. This adjusts the DB levels to compensate. I spent many many hours
following the various guidelines for combatting echo, but with one 2 minute
conversation with Mark, he was able to pin it down. The key I believe was
the loudness of the echo. The echo was as loud as my voice when I spoke.
Using ztmonitor to adjust rx and tx gain had absolutely no noticeable
effect. Also,  under normal circumstances, apparently echo should never
occur when calling from an FXS connected analog phone out an FXO port to the
telco. I had been on a wild goose chase all along. This must be a new fix as
the front line Digium support was unaware. I had to specfically mention it
per Mark's conversation.

On 2/10/06, Sean Cook <scook at kinex.net> wrote:
>
> -----BEGIN PGP SIGNED MESSAGE-----
> Hash: SHA1
>
> hmmm... I have not found this documented anywhere... ;)  Can you
> explain the rationale a bit?
>
> Sean
>
> David K Parker wrote:
>
> > My problem is solved by doing the following. Many thanks to Mark
> > Spencer for clueing me in...
> >
> >
> > search for the following string in wctdm. c:
> >
> > /* Enable on-hook line monitor */
> >
> > After the "wctdm_setreg" function add the following lines:
> >
> > /* Apply negative Tx gain of 4.5db to DAA */ wctdm_setreg(wc, card,
> > 38, 0x14); /* 4db */ wctdm_setreg(wc, card, 40, 0x15);
> > /* 0.5db */
> >
> > /* Apply negative Rx gain of 4.5db to DAA */ wctdm_setreg(wc, card,
> > 39, 0x14); /* 4db */ wctdm_setreg(wc, card, 41, 0x15);
> > /* 0.5db */
> >
> > Save the file, and recompile zaptel
> >
> > On 12/10/05, *David K Parker* <davparker at gmail.com
> > <mailto:davparker at gmail.com>> wrote:
> >
> > I hadn't heard of fxotune. I'll check it out.
> >
> > I had a little bit better luck today after replacing a 25 ft cable
> > on the pstn side with a 7 ft cable. I'm beginning to wonder about
> > ztmonitor though. Before replacing the cable I had to adjust Rx to
> > 22 and Tx to - 7.5. Ztmonitor still showed the Tx gain to be hot.
> > If I went below -7.5 I couldn't complete a call. Now Rx is at 2.5
> > and Tx is at 8. This is adjusted when caling the CO. When I call
> > anyone, the sound is low. I can adjust Rx to 4.5 and its better.
> > The other party hears me fine. I changed the echo canceller to
> > ECHO_CAN_MG2 in Zaptel and the beginning of the call isn't as bad.
> > If I unplug Asterisk from the PSTN and use the analog direct to the
> > telco the quality is fine. Asterisk is poor in comparison on PSTN.
> > Any calls with Asterisk to my Teliax ld trunk are fine.
> >
> >
> > On 12/9/05, *Matthew Fredrickson* < creslin at digium.com
> > <mailto:creslin at digium.com>> wrote:
> >
> >
> > On Dec 9, 2005, at 9:48 AM, David K Parker wrote:
> >
> >> I have a Digium TDM11B, I'm fighting an issue with with echo on
> >> the PSTN side. I run Asterisk at Home 2.0. I have an analog phone on
> >> the FXS channel 1 and Telco on the FXS channel 4. I also have a
> >> coupe of softphones, 1 iax2, the other sip, and a LinkSys Sipura
> >> 941. I use a VOIP provider for long distance. I'm experiencing
> >> echo on all calls on any phone for calls going out over the PSTN,
> >> but no echo at all on Long Distance calls with my VOIP provider
> >> or Internal calls. I think its safe to say that echo is occuring
> >> on the PSTN side on channel 4. I've followed the trouble shooting
> >> provedures on voip-info.org <http://voip-info.org> for echo
> >> cancellation, even calling the local CO using ztmonitor to adjust
> >> rx & tx gain. The only thing I haven't tried yet is installing
> >> shielded cable. I use Verizon DSL for Internet and have the
> >> appropriate filter for my PSTN on channel 4. I'm beginning to
> >> wonder if the problem is due to DSL. Has anyone else had this
> >> experience.
> >>
> >
> > Have you tried running fxotune on the card? It's possible that
> > your echo problem is related to line impedance mismatch. For more
> > details, see README.fxotune in the zaptel package.
> >
> > Matthew Fredrickson
> >
> > _______________________________________________ --Bandwidth and
> > Colocation provided by Easynews.com <http://Easynews.com> --
> >
> > Asterisk-Users mailing list To UNSUBSCRIBE or update options visit:
> > http://lists.digium.com/mailman/listinfo/asterisk-users
> >
> >
> >
> >
> > ----------------------------------------------------------------------
> >
> >
> > _______________________________________________ --Bandwidth and
> > Colocation provided by Easynews.com --
> >
> > Asterisk-Users mailing list To UNSUBSCRIBE or update options visit:
> > http://lists.digium.com/mailman/listinfo/asterisk-users
> -----BEGIN PGP SIGNATURE-----
> Version: GnuPG v1.4.2 (MingW32)
> Comment: Using GnuPG with Thunderbird - http://enigmail.mozdev.org
>
> iD8DBQFD7QTCy9wPyZpnL2URAqhbAJsFameIwYh9qTwLYGc5k1JFXTw5vgCeLKM4
> zScxRwbwB1acgbTgBeQIUYE=
> =Hw91
> -----END PGP SIGNATURE-----
>
> _______________________________________________
> --Bandwidth and Colocation provided by Easynews.com --
>
> Asterisk-Users mailing list
> To UNSUBSCRIBE or update options visit:
>    http://lists.digium.com/mailman/listinfo/asterisk-users
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: http://lists.digium.com/pipermail/asterisk-users/attachments/20060211/92f1b609/attachment.htm