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

[David K Parker]

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> 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> 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 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
> >
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