[arm-allstar] radioless node dtmf problem

[Doug Crompton]

Alan,

  The problem with DTMF created in microphones is the wide range of levels
and often bad tones especially in clone products. That is why in our
radio-less design we use the Yaesu mic and create the DTMF tones in the
box. Not to say it won't work but for production you can't have that
uncertainty. In your case assuming the mic is actually putting out tones is
to play with the levels and then watch in the Asterisk client to see if the
tones are being decoded. I suspect it is a level issue although if it is
not a real Alinco mic supplied with an Alinco radio it may be a knock-off
or an Alinco reject sold on ebay. We ran into a lot of that in our first
radio-less design with 9 out of 10 not working and sending them back.

Most DTMF in the mic products also have a pot inside to set the DTMF level
so you can play with that also. The one I made several years ago that is
shown in the howto's at the hamvoip.org web page used a mic from an Alinco
radio I purchased and it worked fine. I did not have to mess with anything
inside the mic to get it to work.

One caution for anyone building a radioless node and directly connecting a
mic to the FOB is that there is no limiting or compression and you really
need to set the mic level lower on average audio so the peaks do not clip.
A good addition would be this board between the mic and the FOB. This is
what we use in our radio-less design.

https://www.ebay.com/itm/332468614881

It uses an Analog Devices chip and works very well. This would also help
your DTMF problems if it is due to levels.


*73 Doug*

*WA3DSP*

*http://www.crompton.com/hamradio <http://www.crompton.com/hamradio>*

On Mon, Apr 22, 2019 at 1:06 PM "Alan Matthews via ARM-allstar" <
arm-allstar at hamvoip.org> wrote:

> hi group
>
> I have made a radioless node and it works fine. However I am using an
> alinco EMS-57 dtmf mike powered by 5 volts from the usb, I am not sending
> any dtmf tones. Is there a setting in the software that needs adjusting?,
> or am i overlooking something. I assume this mike should work with dtmf for
> the radioless node.
>
> any help would be appreciated.
>
> regards Alan
>
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