[asterisk-users] noisy analog lines

[Tzafrir Cohen]

One other thing,

On Fri, Apr 25, 2008 at 10:06:08AM +0200, Ian wrote:
> Hi all
> 
> I have a small problem here.
> 
> We are running Asterisk 1.4.18 and libpri 1.4.3 (how can I check the 
> zaptel version again?) on an Intel core 2 duo 1.6Ghz, 2GB ram under 
> Ubuntu server.
> 
> We have 4 analog line coming into the box via a TDM 800 wildcard with 
> echo cancel module and quad fxo modules.
> 
> The server has been running smoothly with almost no problems for awhile now.
> 
> Recently I started picking up problem with the voice clarity on our end, 
> it sounds like a mobile going through a low signal patch. I asked the 
> person on the other end and they can hear me loud and clear.
> 
> I bumped the txgain up a notch a while back, can it be because of this?

You bumped both txgain and rxgain. txgain is for audio Asterisk
transmits to the device (the telephone line, in this case). rxgain is
for audio recieves from the device.

I suspect you don't really need both . And a value of 10 might actually
influence the echo canceller. Try removing the two and see how things
work. Generally this value (like most values) is applied on a reload
(with asterisk 1.6 you can even use 'zap set {hw|sw}gain') . Generally
remove all of those txgain and rxgain limes from your zapata.conf, and
leave potentially just one near the top of the [channels] section - it
will effect all of them. 

Use 'reload' or 'module reload chan_zap.so' to apply your changes and
ignore the scary messages about the "signalling" being ignored.

-- 
               Tzafrir Cohen
icq#16849755              jabber:tzafrir.cohen at xorcom.com
+972-50-7952406           mailto:tzafrir.cohen at xorcom.com
http://www.xorcom.com  iax:guest at local.xorcom.com/tzafrir