[asterisk-bugs] [Zaptel 0007136]: [patch] FXOTune doesn't properly clear the dialtone before performing tests

[noreply at bugs.digium.com]

A NOTE has been added to this issue. 
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http://bugs.digium.com/view.php?id=7136 
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Reported By:                trumpetinc
Assigned To:                file
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Project:                    Zaptel
Issue ID:                   7136
Category:                   Utilities
Reproducibility:            always
Severity:                   major
Priority:                   normal
Status:                     closed
Zaptel Version:             SVN 
SVN Branch (only for SVN checkouts, not tarball releases):  1.2 
SVN Revision (number only!): 1033 
Disclaimer on File?:        Yes 
Request Review:              
Resolution:                 fixed
Fixed in Version:           
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Date Submitted:             05-10-2006 16:26 CDT
Last Modified:              06-07-2008 11:35 CDT
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Summary:                    [patch] FXOTune doesn't properly clear the dialtone
before performing tests
Description: 
NOTE:  I'm marking this as 'major' because the bugs in fxotune prevent
users who are experiencing echo from being able to solve their problem. 
I'm not sure if this really justifies the 'major' categorization, so I'm
fine with it being downgraded - but we were right on the edge of abandoning
the TDM altogether, and this patch made all the difference.

FXOTune does not wait after sending the dial string (used to clear the
dial tone) before it begins testing.  The result is that a good 30-40% of
the tests performed wind up measuring output of the dial tone, and not echo
response.

To check this out for yourself, hook a 2x2x2 (or 4x4x4) splitter to the
TDM jack, your outside phoneline to one side of the splitter and a
telephone to the other side.  Run:

fxotune -i 5

Wait a couple of seconds, then pick up the telephone.  Note that some of
the test tones get sent while there is still a dialtone.

Another way to get at this:  
1.  turn fxotune debug on
2.  Change the line that reads:

		for (i = 0; i < 252; i++) {

so it only runs one channel's worth of tests (otherwise the debug output
gets blown away for each channel):

		for (i = 3; i < 3; i++) {  // only test channel Zap/4  (i+1 = 3+1 = 4)

3.  recompile
4.  run fxotune -i 5 
5.  Get a baseline power level for each frequency and channel
6.  pick up the telephone (from above) and dial '5' to clear the dialtone
7.  immediately run fxotune -i 5
8.  check the baseline power levels for each frequency and note that some
of them are completely different, and some are the same


This patch fixes the above problem by inserting an extra second delay
after sending the dial string, and sets the needtoreset counter to a high
value to force the dialtone clearing to take place before the first 8
frequencies are run.  It also adds a new calibration mode (-i2) and a mode
for dumping waveforms (-d).  See the 'Additional Information' section for
details.


Once I configured fxotune.conf with the *correct* settings resulting from
these changes and tuning all of the echo coefficients (instead of just the
line impedence) using the -i2 option (see 'Additional Information' for the
new -i2 option), my echo problem dropped dramatically (60% response to 5%
response).  The software echo canceller was then able to handle the 5%
response, and we now have crystal clear outside lines.

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---------------------------------------------------------------------- 
 svnbot - 06-07-08 11:35  
---------------------------------------------------------------------- 
Repository: dahdi
Revision: 1073

U   branches/1.2/fxotune.c

------------------------------------------------------------------------
r1073 | file | 2008-06-07 11:35:31 -0500 (Sat, 07 Jun 2008) | 2 lines

Clear dialtone before running tests (issue
http://bugs.digium.com/view.php?id=7136 reported and fixed by
trumpetinc)

------------------------------------------------------------------------

http://svn.digium.com/view/dahdi?view=rev&revision=1073 

Issue History 
Date Modified   Username       Field                    Change               
====================================================================== 
06-07-08 11:35  svnbot         Checkin                                      
06-07-08 11:35  svnbot         Note Added: 0088119                          
======================================================================