[asterisk-users] Voice low on ZAP

[Matt Watson]

On May 26, 2008 07:19:07 pm Sanjay Rajdev wrote:
> I have a Sangoma A200 card on my asterisk box, the sound that is received
> on the ZAP channel is very low, I is sometime difficult to hear the person
> on the other side of the line. Is there a way we can increase the volume on
> the ZAP channel
>
>
> Regards,
> Sanjay Rajdev

rxgain= 
in zapata.conf

However, before you go blindly upping the value, you should know that you run 
the risk of making echo problems worse by messing around with rxgain/txgain.  
However, tuning rxgain/txgain is something that you *should* do on all your 
FXO ports anyways... properly tuned ports will create far less echo than 
those using default values most of the time.

Tuning rxgain/txgain is a little bit of a tedious task however, and I can;t 
really say there are alot of good guides out there on how to do it.

The way I did it was first I tuned my rxgain by dialing a telco-owned 
milliwatt test number (should be able to get this from your telco, i believe 
its referred to as a Type 102 milliwatt test).  You use that to tune rxgain, 
then the way I tuned txgain was by using the app_milliwatt application to 
essentially create my own milliwatt test number (need multiple FXO ports to 
do this), so basically i;d dial out from one FXO port and back into the other 
and adjust the txgain until i got it right...

You need to use ztmonitor to watch the levels as you adjust tx/rxgain, I 
believe the magic number you want to hit in ztmonitor is around 14840 (thats 
off the top of my head so i might be off)...


-- 
Matt
http://www.mattgwatson.ca