[asterisk-users] fxotune question

[Matthew Fredrickson]

John Morey wrote:
> I switch the wires in lines 5-8 (i.e. reversed tip and ring) and reran
> fxotune to tune the lines.  fxotune.conf ended up looking exactly the same
> as before the change.  Since I was expecting/hopping to see a change but did
> not I switched everything back to the way it was. Is there a way to test the
> lines, using a multi-meter maybe, to tell if the tip and ring are correct or
> reversed?
> 
> After putting things back I reran fxotune to get the verbose output. It,
> foxtune.out.gz, is attached.  fxotune seems to have had a better time with
> line 7 during this run.  fxotune.conf now contains:
> 
>    5=7,255,251,251,2,255,255,1,255
>    6=7,255,251,251,2,255,255,1,255
>    7=4,0,0,0,0,0,0,0,0
>    8=7,255,251,251,2,255,255,1,255
>    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
> 
> I tried calling directly into the lines above and it seems lines 5,6,8 have
> much more echo than lines 7,9,10. So just for fun I edited fxotune.conf to
> the following and reloaded (fxotune -s) it:
> 
>    5=5,0,0,0,0,0,0,0,0
>    6=5,0,0,0,0,0,0,0,0
>    7=4,0,0,0,0,0,0,0,0
>    8=5,0,0,0,0,0,0,0,0
>    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
> 
> Unless I am just spacing out the echo on 5,6,8 seems less now.  I really
> have no idea what is going on.

Ok, I looked at the output of you running fxotune.  Basically, the lines 
that have numbers in them besides 0 (after the first two terms x=y,...) 
are the complex line simulation line models.  The output you gave me 
demonstrated that they gave the best return loss characteristics using 
the built in test frequencies.

It's possible that your setup is not performing well with these line 
models, which is why you might notice less echo using the second set of 
settings you listed above.  Which echo canceller are you using with 
this, by the way? (Hardware, software, if software, which software echo 
canceller).

Matthew Fredrickson

> 
> John
> 
> 
> On Fri, Jun 6, 2008 at 1:31 PM, Matthew Fredrickson <creslin at digium.com>
> wrote:
> 
>> John Morey wrote:
>>> Tilghman,
>>>
>>> Thanks for the pointer.  I'll check this tomorrow and let you know.
>> Also, I would like to see the output without the "-d" flag and with the
>> "-v" flag.  This will output a lot of data (the echo ratio for every
>> possible coefficient setting it has tried per port).
>>
>> Matthew Fredrickson
>>
>>> John
>>>
>>> On Wed, Jun 4, 2008 at 11:18 PM, Tilghman Lesher <
>>> tilghman at mail.jeffandtilghman.com> 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.
>>>>
>>>> --
>>>> Tilghman
>>>>
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>>>
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>>
>> --
>> Matthew Fredrickson
>> Software/Firmware Engineer
>> Digium, Inc.
>>
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-- 
Matthew Fredrickson
Software/Firmware Engineer
Digium, Inc.