[Asterisk-Users] How to 'read' ztmonitor and set gains

[Seth Remington]

On Fri, 2005-07-15 at 20:44 -0700, Chris Coulthurst wrote:
> Being one the many people trying to track down echo 'ghosts' I ran across
> this page: 
> 
> http://lists.digium.com/pipermail/asterisk-users/2004-November/071301.html
> suggesting ways to adjust the gain.  I have a TDM400P 2x2 config with
> Kewlstart lines configured.  I've located a local telco milliwatt test line,
> and when I call it, the gain numbers are no where near 14844.  Now, this
> article refers to configuration with a channel bank, but suggests it would
> be similar on 'simpler equipment'.
> 
> The numbers I get are around 4450 on the Rx.  
> 
> [root at morse zaptel]# ./ztmonitor 5 -vv
> 
> Visual Audio Levels.
> --------------------
>  Use zapata.conf file to adjust the gains if needed.
> 
> ( # = Audio Level  * = Max Audio Hit )
> <----------------(RX)---------------->
> <----------------(TX)---------------->
>  ########################*
> Rx:  4452 ( 4452) Tx:    46 (   63)
> 
> Is this good? Normal? Any suggestions, or a point in the right direction for
> the right documentation would be appreciated.
> 
> P.S. This is CVS-HEAD Zaptel on a P3 550, Host bridge: Intel Corp.
> 440BX/ZX/DX - 82443BX/ZX/DX Host bridge (rev 3)
> 
> Chris Coulthurst
> chris at shuksan.com

I tried to follow the instructions in that message as well and my
findings were the same as yours. I forget what they were exactly but by
the time I boosted my gains to approach a reading of 14844 I was
boosting by some insane db level and, as would be expected, my signal
was severely distorted and way outside the range of what the mec2 echo
canceler could handle. The only thing I noticed that might indicate
where the 14844 number came from is that if you monitor a channel that
is executing the Milliwatt() app it will report a tx level of.....
14844.


-Seth


-- 
Seth Remington
SaberLogic, LLC
661-B Weber Drive
Wadsworth, Ohio 44281
Phone: (330)335-6442
Fax: (330)336-8559