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I have a baofeng DMR radio with SMS feature, and since there is not much DMR radio owners in my area I want to do something myself.

The easiest thing I can do I thought is to send myself some SMS as I did with a POCSAG pager using my hackrf one.

But I haven't found any software to do that. All I found is MMDVM-SDR program on github which acts as a MMDVM modem utilizing a fake serial port. It allows to get commands from the MMDVM-Host and modulate them as IQ WAV file.

There is one problem: that MMDVM modem protocol has no commands to send DMR SMS. It only accepts "DMR DATA packet" at different rates. I tried to google for "DMR AIR interface" but it also has no mentions of SMS.

By that time I learned that DMR SMS is a non-standartized thing which leaves me with this questions (one is part of the another):

  • What format all those TYT and Baofeng radios is using, where I can get it's datasheet.
  • How to make a DMR SMS packet for my radio and send it to a MMDVM modem emulator or directly to the SDR using some other modem software?

PS: I tried to record my radio's signal with SDR and play it back. With voice it works, I can hear myself, but with SMS it doesn't work for some reason: my radio just ignores them (maybe that is because it's number in both from and to fields?)

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Message sending is not part of DMR standard. Messages are transmitted in CSBKs, Control Signalling Blocks

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    $\begingroup$ Hello and welcome to ham.stackexchange.com! Please consider expanding your answer with a little more background and explanation. $\endgroup$
    – rclocher3
    Commented Mar 17, 2020 at 18:38
  • $\begingroup$ What format do SMS take in a CSBK? I can find ETSI documents that explain how to go from a CSBK all the way to modulated RF, but I can't find a document that describes how I go from an SMS message to a CSBK. $\endgroup$
    – Simon Farnsworth
    Commented Dec 5, 2023 at 17:56
  • $\begingroup$ How I said it is not part of DMR standard. $\endgroup$
    – Gábor
    Commented Dec 7, 2023 at 20:03
  • $\begingroup$ Right, it's not part of the ETSI DMR standard. But given that multiple radios handle SMS compatibly, it's plausible that there's another document (not the ETSI standard) that documents how you build a CSBK that represents an SMS $\endgroup$
    – Simon Farnsworth
    Commented Dec 13, 2023 at 17:06

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