[Asterisk-Users] Re: Connection TDM400P to UK PSTN

[Chris Earle (CBL)]

Hey all

would you believe this problem is still going on?

I have now successfully secured individual IRQs for the two TDM cards, but
no change has been observed.  No interrupts appear to be getting dropped or
anything along those lines.

Also tried moving the FXO and FXS modules around on the cards.  No
changes -- not completely clear if the card is defective or not.  Can you
shed any light on that?

I am using Zaptel 1.2.2, with the MG2 echo canceller, but only with Asterisk
1.0.9.  I am not prepared to upgrade to a more recent 1.2 version unless I
think that will provide massive benefits (I don't think it will affect my
zaptel/echo problem?)

Back to the card situation: we have not tried any other machines or cards.
We are starting to consider using a different card -- and would prefer to
stick with Digium hardware.  The newer, larger, TDM2400 is under
consideration because it has echo cancellation onboard --- Do you think this
will do anything??

Also, tried the phone on the phoneline straight up -- sounded fine.  We
tried the phoneline with a US phone and also a UK
one.

So is hardware EC the solution to my woes?



Chris

----- Original Message ----- 
From: "Chris Earle (CBL)" <cearle at cbltech.ca>
To: "Chris Bagnall" <asterisk at minotaur.cc>; "'Asterisk Users Mailing List -
Non-Commercial Discussion'" <asterisk-users at lists.digium.com>
Sent: Monday, January 23, 2006 5:24 PM
Subject: Re: [Asterisk-Users] Re: Connection TDM400P to UK PSTN


> Thanks for that, insightful
>
> The quality on both ends with those settings is quite good -- but the
> extension side still has a ridiculous -- almost duplicate -- echo!
>
> If I turn the txgain right down, I lose all sound.....of course the
signals
> in ztmonitor show up perfect then, but can't hear anything (DTMF tones too
> low or whatever...)
>
> Still wondering if it's an impedance issue...or something along those
> lines/chipset..etc....
>
> I'm going to attempt upgrading Zaptel now, without upgrading the asterisk
>
>
> Chris
>
>
> ----- Original Message ----- 
> From: "Chris Bagnall" <asterisk at minotaur.cc>
> To: "'Chris Earle (CBL)'" <cearle at cbltech.ca>; "'Asterisk Users Mailing
> List - Non-Commercial Discussion'" <asterisk-users at lists.digium.com>
> Sent: Sunday, January 22, 2006 9:13 AM
> Subject: RE: [Asterisk-Users] Re: Connection TDM400P to UK PSTN
>
>
> > > Successfully got the adapters to allow the BT phones to ring
> > > on lines coming out of a TDM.......... but now my latest
> > > problem is echo.
> > > Suggestions / Experiences in UK appreciated
> >
> > Most of our clients with BT lines tend to have ISDN BRIs, but we do have
> one
> > in Northampton running 3 analogue lines from a TDM400.
> >
> > zaptel.conf is as follows:
> > fxsks       = 1-3
> > loadzone    = uk
> > defaultzone = uk
> >
> > The TDM driver is loaded with opermode=UK and the output from dmesg
> confirms
> > this.
> >
> > Relevant settings from zapata.conf are as follows:
> > echocancel=yes
> > echocancelwhenbridged=yes
> > echotraining=800
> > rxgain=8.0
> > txgain=-4.0
> > busydetect=yes
> > group   = 1
> > context = inbound
> > channel => 1-2
> > group   = 2
> > context = inbound
> > channel => 3
> >
> > They're running Asterisk/Zaptel 1.0.10. There were major echo issues
when
> we
> > first deployed the system back in September, but some careful tweaking
of
> > rxgain and txgain seems to have largely resolved the situation.
Certainly
> my
> > experience has been that rxgain and txgain have far more impact on echo
> > reduction than any of the echo-specific settings. Get the gains right
> first,
> > then play with the echo-specific settings.
> >
> > Regards,


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