DMR Data Mode

[AA3RP]

One of the things that has had my interest about digital RF communications via radio is the possibility of 'DATA' only modes. Not going to get technical or such, but the idea of connecting a radio that has DMR to a computer and sending information between computers using the DATA mode of the DMR specification should / might be doable.

As far as I know all my interaction and study of DMR radios is that they are used for digital VOICE and not much else. Yes there is ID data passed and such but it is part of VOICE digital standard part of DMR. I understand correctly DMR has two and possibly three digital tx/rx formats:
1. digital VOICE
2. digital DATA
3. (maybe) mixed digital VOICE / DATA

I have seen one and two listed for every DMR radio I am aware of and some list the mixed digital Voice / Data.

I am curious if there is a way to use the DATA only mode.

[VK3KYY]

The firmware does not support any pure data modes.

Various developers have attempted to implement SMS / Text data but have failed to do so, due to the lack of documentation on the DMR chip used by these radios, and also because some of the SMS / Text formats are either priorprietary and protected by patents and trademarks or undocumented.

At its most basic level, DMR just sends data, but unless the data is in a format exceptable to repeaters and networks, then it would only be useful for specific simplex applications.
So its also not just a question of the firmware being able to send pure data, but also that the networks can handle whatever DMR data is being transmitted.

If you want to experiment with simplex transmission of nonstandard DMR , you can download the source code to for the released versions of the project, on both the GD77 and also UV380/RT3S style radios and experiment with sending whatever you like, but you would need at least 2 radios, i.e for Tx and one for Rx because no network will accept non-standard DMR frames.
Bear in mind that there is no documentation of how to do this

[AA3RP]

The firmware does not support any pure data modes.

Various developers have attempted to implement SMS / Text data but have failed to do so, due to the lack of documentation on the DMR chip used by these radios, and also because some of the SMS / Text formats are either priorprietary and protected by patents and trademarks or undocumented.

At its most basic level, DMR just sends data, but unless the data is in a format exceptable to repeaters and networks, then it would only be useful for specific simplex applications.
So its also not just a question of the firmware being able to send pure data, but also that the networks can handle whatever DMR data is being transmitted.

If you want to experiment with simplex transmission of nonstandard DMR , you can download the source code to for the released versions of the project, on both the GD77 and also UV380/RT3S style radios and experiment with sending whatever you like, but you would need at least 2 radios, i.e for Tx and one for Rx because no network will accept non-standard DMR frames.
Bear in mind that there is no documentation of how to do this

Thank you for the timely reply.

If I understand you correctly there is a lack of public documentation and information on the DMR chip used in the radios supported by this project. That is unfortunate, and I assume those that have attempted to do SMS / Text have looked and searched for it.

From what I have come across without going to the official DMR specification so far is that the DATA only mode of DMR is an IP based (or at least compatible) format so it can interface well at DMR level III Trunking system that most likely already have IP backhaul and communication.

Regardless of this it does not seem worth the time or effort to pursue without clear information on the DMR chip and interface of the DMR to the radio.

All the best
AA3RP

[OE6BZD]

Just out of curiosity; since short messages are supported by the original firmware of the GD77, did anyone ever attempt to sniff and reverse engineer the communication between the MCU and the Baseband IC with a logic analyzer while sending a SMS?
BR & 73
Nico, OE6BZD

[VK3KYY]

Just out of curiosity; since short messages are supported by the original firmware of the GD77, did anyone ever attempt to sniff and reverse engineer the communication between the MCU and the Baseband IC with a logic analyzer while sending a SMS?
BR & 73
Nico, OE6BZD

Yes. I'm sure thats partially what the developers who attempted to implement SMS did.

You would need to contact them directly to find out eaxtly their method if you plan to attempt this yourself.

Try reading this post

viewtopic.php?f=16&t=1797&p=15483#p15483