[App_rpt-users] RPi 3 controller problem (Steve Zingman)

[Bryan Taylor]

Here's another suggestion I use all the time and I don't get any false dtmf's since doing this, this is an email sent by chuck Henderson, 



I do not do it the official way.  I found the 2 official settings each had problems, Either too much falsing, or some TT pads would not decode.
The official way changes a value in a config file that lets the compile choose between a value of 26 when relaxed and 42 when not relaxed. Default is relaxed.
My method allows to fine tune and select the just right value somewhere between 26 and 42.  26 being too relaxed (voice falsing) and 42 being to strict (some TT pads will not work over the air on less than perfect signals.

So that being said, I edit the main/dsp.c file and this is the line I edit.  Without and with the change.
#define DTMF_TO_TOTAL_ENERGY    ((digitmode & DSP_DIGITMODE_RELAXDTMF) ? 26.0 : 42.0)   /* before change */
#define DTMF_TO_TOTAL_ENERGY    ((digitmode & DSP_DIGITMODE_RELAXDTMF) ? 38.0 : 42.0)  /* CAH after I changed 26 to 38 */

To find it just search main/dsp.c for RELAXDTMF
Then when you find the line, change the 26 to a 38, leave the 42 as it is.

then recompile

You can fine tune the value by experimentation but the value that was the best compromise for me was 38.
Add a comment as I did so that in a year or two when you can't remember what that change was to fix the TT problem, you can just grep for your initials in the source files and find the file and line that has the changes.
You also have to remember to redo your edit every time that you upgrade the code.
Chuck
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