[asterisk-users] fxotune question

[Tilghman Lesher]

On Thursday 05 June 2008 09:17:49 Drew Gibson wrote:
> Tilghman Lesher wrote:
> > On Wednesday 04 June 2008 22:02:19 John Morey wrote:
> >> Hello,
> >>
> >> I've run fxotune 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.
> >>
> >> 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?
> >
> > You might check to see if the tip and ring are reversed in your wiring. 
> > That can frequently cause weird echo problems.
>
> Which ports would you expect to be reversed? 5-8 or 9-10?

I'd suspect 5-8 have the tip and ring reversed.  9-10 look like they have
almost no detected echo at all.

> I have similar settings in my fxotune.conf for a TDM2400P and I'm
> getting complaints of "static" on the line that I suspect are related to
> an overtaxed h/w echo canceller
>
> My fxotune.conf:-
>
> 13=7,255,251,251,2,255,255,1,255
> 14=9,254,251,255,2,0,1,0,0
> 15=9,254,251,255,2,0,1,0,0
> 16=5,0,0,0,0,0,0,0,0
> 17=9,254,251,255,2,0,1,0,0
> 18=9,254,251,255,2,0,1,0,0
> 19=9,254,251,255,2,0,1,0,0
> 20=9,254,251,255,2,0,1,0,0
> 21=9,254,251,255,2,0,1,0,0
> 22=9,254,251,255,2,0,1,0,0
> 23=9,254,251,255,2,0,1,0,0
> 24=9,254,251,255,2,0,1,0,0

You certainly could flip one pair, re-run fxotune (or just manually set it
to the same as line 16) and see if the sound dramatically improves on that
channel.

-- 
Tilghman