[Asterisk-Users] Static on TDM Zaptel FXO

Wed May 18 14:11:19 MST 2005

Greg, 

The rxgain and txgain settings are essentially used to address the
pstn cable loss between your asterisk box and the central office.
If you were located right next to the central office, then settings
around 0.0 might work well. The further away you are from the central
office the greater the gain number needed to compensate for that loss.

The negative side of that is that if the gain settings are too high,
you're likely to have echo on every call. So, start with something
like rxgain=3.0 and txgain=3.0 and place a test call. If echo, drop
both settings down by 3 (rxgain=0.0 & txgain=0.0) and repeat.

Each time you change those settings in zapata.conf, you will need to
stop asterisk and restart it. A reload won't change the settings.

FWIW, I'm 7db from my central office and am using rxgain=5.0 and
txgain=1.0 for now.

------------------------
> I still need to experiment with it, so I am not sure yet.  When I have
> it I will post the settings.  I really don't have a clear understanding
> yet of the principles for using gain.  Are there, for example, specific
> reasons for different settings.  All I want is to be sure I can hear the
> other party, and they can hear me in the proper volume.
> 
> Greg 
> 
> -----Original Message-----
> From: asterisk-users-bounces at lists.digium.com
> [mailto:asterisk-users-bounces at lists.digium.com] On Behalf Of Gary Carr
> Sent: Wednesday, May 18, 2005 11:29 AM
> To: Asterisk Users Mailing List - Non-Commercial Discussion
> Subject: Re: [Asterisk-Users] Static on TDM Zaptel FXO
> 
> I have that exact setup and am getting a echo at the beginning of a
> inbound call. What gain settings work best for you?
> 
> 
> 
> 
> Gary
> 
> 
> 
> 
> Hello Bryce,
> Gain settings do seem to have an effect.  I am going from a Cisco
> 7960>Asterisk>Zap TDM Card>POTS
> 
> Thanks,
> Greg
> 
> -----Original Message-----
> From: asterisk-users-bounces at lists.digium.com
> [mailto:asterisk-users-bounces at lists.digium.com] On Behalf Of Bryce
> Chidester
> Sent: Wednesday, May 18, 2005 1:08 AM
> To: Asterisk Users Mailing List - Non-Commercial Discussion
> Subject: Re: [Asterisk-Users] Static on TDM Zaptel FXO
> 
> That type of echo is usually caused by incorrectly (or not at all) tuned
> gain settings in zapata.conf. I don't know what kind of phones you're
> using, but for Asterisk to even be able to detect DTMF tones on our
> Sayson / Aastra 390s and 480s, our FXS channels are set to -5.0 on both
> rx and txgain. If you're using externally-powered phones (as in not your
> ordinary joe-schmoe analog phone), I have found that they're usually
> pretty "hot" (loud) and Asterisk can't understand what is said.
> Good luck!
> 
> Regards,
> Bryce Chidester
> Rhino Equipment Corp.
> bryce at rhinoequipment.com        SIP: 305 at rhinoequipment.zapto.org
> +1 (480) 940-1826 x305                IAX:
> guest at rhinoequipment.zapto.org/305
> 
> 
> On May 17, 2005, at 19:00, Gregory Wiktor - ADCom Corp. wrote:
> 
> 
> > On a recompile of the kernel I now get a 99.98 average.
> > Static is gone, although quality so far seems not quite there yet.
> >
> > I am also experiencing an odd local echo.  I can hear a slight echo
> > locally, but the other end sounds fine, and the other end does not get
> 
> > echo.
> >
> > Even with the pots disconnected, you can hear it.  The static would be
> 
> > on all calls.  Hooking up a normal phone was ok.  The sip>sip phones
> > are perfect too, it was only happening on the zap channel...
> >
> > Greg
> >
> > -----Original Message-----
> > From: asterisk-users-bounces at lists.digium.com
> > [mailto:asterisk-users-bounces at lists.digium.com] On Behalf Of Jeremy
> > Parr
> > Sent: Monday, May 16, 2005 8:05 PM
> > To: Asterisk Users Mailing List - Non-Commercial Discussion
> > Subject: Re: [Asterisk-Users] Static on TDM Zaptel FXO
> >
> > On 5/16/05, Gregory Wiktor - ADCom Corp. <gw at adcomcorp.com> wrote:
> >
> >
> >> Hello All,
> >> I recently put in a zaptel 1fxo/1fxs card.  I am experiencing heavy
> >> static.
> >>
> >> Even with the pots line disconnected, if I do a dial I still get
> >>
> >>
> > static.
> >
> >
> >> This way I know it's not the line, but rather something on the card.
> >>
> >> I tried alternate pci slots.
> >>
> >> This card has a power connector, does anyone know what the power
> >> requirements are?  The unit is in a small case with a 2.4ghz p-4 and
> >> 512mb ram, on an intel board with 533fsb.  All other functions are
> >>
> >>
> > fine.
> >
> >
> >>
> >> I am using the latest CVS on Debian 2.6test
> >>
> >> Anyone experience this?
> >>
> >>
> >
> > Have you tried a different phone? Does the static appear immediately
> > when you pick up the phone? Or on the second or third time?
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> >
> 
> 
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