There are currently some problems with the DTMF and 1750Hz Tone deviation, and the DTMF and tone audible feedback through the speaker is too loud
Ray VK3YNV emailed me to say that the DTMF deviation seems to be too high and is causing distortion.
The problem seems to be that the DTMF and Tone require a different master deviation setting to the normal FM audio.
The calibration data contains deviation settings for both of these but we did not use the settings in the OpenGD77 as the DTMF and 1750 tones sounded OK and seemed to work OK.
Anyway, Alex DL4LEX and I are aware of this problem and I think Alex is working on a solution.
With the audible feedback for the 1750Hz tone and the DTMF tones, I think the tones may be louder because the deviation is currently too high.
If after the deviation is reduced the audible feedback is still too loud it would be possible to reduce the overall audio gain on the AT1846S RF chip while the tones are being played.
I have not used either DTMF or 1750Hz in the official firmware, but I think possibly the audible feedback is too loud even on the official firmware, so I could either have a fixed amount of audio reduction when the tone is being played, or perhaps have a setting in the Options menu to control this. However because I don’t think this is something which is a big problem, adding a setting for this is probably overkill