DTMFs on IMBE P25

[W1HVN]

Without going in and trying, on ther 3k or 5k, is it possible to send DTMFs over P25 Conventional with the keypad? I would assume no, but one never knows.

Application: taking P25 Astro Spectra and adapting it to be used on a analog repeater controller (amateur use). It will serve as a remote base for P25 on an analog repeater system. Would like to control repeater through DTMFs from audio tapped off the Astro Spectra. Unorthodox, but just an idea cooking. Will link P25 world to analog world for emcomm use (for those without P25). Next question will be where to tap audio from the Astro Spectra for rx and tx and a NAC sense line (similar to Tone Squelch for analog) to key. That will be research for another thread.

Ideas? Nay Sayers? All welcome!

Thanks

[Tom in D.C.]

The IMBE vocoder doesn't like tones and does a poor job of processing them.

[wd9cms]

I have programed the receiver on a P25 ASTRO SPECTRA to allow mixed mode that I use on Echolink. I transmit DTMF in analog for command and control on Echolink and then use P25 digital for voice. It has work very well for the last five years. It lets me experiment with IMBE without requiring the other station to have a P25 radio. This should work in you application if I understand it correctly. Good luck and I hope this helps....

Bill

[515]

Most all the Motorola Astro radios can transmit "digital DTMF" as packet data. It was intended for phone patch operation. When properly programmed on a P25 conventional channel, the radio will send a brief data packet containing up to about 34 DTMF digits. I think it can also work on a P25 trunked system, but I haven't played with that...

Unfortunately, none of the Motorola radios will decode the "digital DTMF". They just stay muted whenever these packets are received. The DIU3000 will decode these packets, and produce analog DTMF tones at the "PATCH" connector. So, if you had a Quantar base or repeater and a DIU3000, you could use a standard phone patch or any other device that decodes DTMF in the digital mode.

Newer EFJ P25 radios can send these digital DTMF packets, as well.

Also, these packets are always in the clear, regardless of the radio's current clear/secure state.

While you probably won't be able to decode any digital DTMF with an Astro Spectra, the mixed mode setup would probably work... For your COR line, you'll want to look for an "audio unmute" line of some kind. This should work for both analog and digital signals...

[radioinstl]

the newer AMBE++ vocoder will do it no prob... ie: Liberty, newer EFJ, APX

[w2sjw]

I was going to say the same (before any of you kill me!) - My ICOM D-STAR units (AMBE2020) sends & receives DTMF as well. My model-III XTS units will not...