[asterisk-users] fxotune question

[Tzafrir Cohen]

On Wed, Jun 04, 2008 at 11:02:19PM -0400, John Morey wrote:
> Hello,
> 
> I've run fxotune 

Of which zaptel version, exactly?

> at different times but continue to get what seem to be
> strange numbers in /etc/fxotune.conf.  It ends up with:
> 
>     5=7,255,251,251,2,255,255,1,255
>     6=7,255,251,251,2,255,255,1,255
>     7=7,255,251,251,2,255,255,1,255
>     8=9,2,250,253,4,252,0,255,255
>     9=4,0,0,0,0,0,0,0,0
>     10=5,0,0,0,0,0,0,0,0
>     11=0,0,0,0,0,0,0,0,0
>     12=0,0,0,0,0,0,0,0,0
> ports 5-10 have lines hooked up to them.  The first four lines seem strange
> when compaired to what others have posted and what ports 9 and 10 have.

fxotune works by setting the values of some specific registers in a
specific chip used for the FXO adapters. In the "set" mode (-s) it
merely takes a set of values from /etc/fxotune.conf and applies them to
the chips of the Zaptel device in the respective ports.

In the "tuning" mode (-i or -d) it will attempt to find the best set of
register values for your ports. It does that basically by systematically
applying many possible sets and and checking the echo level with it.

If nothing is connected to the port, no set of value is better than the
default values (all zeros), and hence those will remain.

> 
> Also if I'm reading things right my echo ratios seem to be very
> high.  Running "fxotune -d -b 5 -w 1004" gives the following:
>     Dumping module /dev/zap/5
>     echo ratio = 0.1759 (1960.0 / 11145.0)
> Which I read to be over 17%.  This seems crazy.  Am I reading this right?
> Where should I start to look for problems?

An echo canceller is still generally useful for an FXO adapter.

-- 
               Tzafrir Cohen
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