[asterisk-users] fxotune question

[Eric "ManxPower" Wieling]

Echo Canceler Freak Out, this happens when the rxgain is too high and 
the echo canceler freaks out.  Some users describe it as "screeching", 
"feedback", "static", or other useless terms.  If users report "static" 
on a system where there cannot be static (all digital, PRI, SIP, etc), 
you might be experiencing ECFO.

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 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
> 
> regards,
> 
> Drew
> 

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