Sunday, December 11, 2016

DVMEGA Raspberry Pi DMR with TYT-380

This is going to be one of those posts that if you don't know much about the won't know much more at the end.

Long story as short as I can...

The lastest technology available to Amateur Radio hobbyists is digital audio.   So same radio frequencies, but instead of analog audio like on your old walkie is digital audio like your cellphone/skype/etc.  Why? More conversations on a frequency, better audio, 'caller id, internet connectivity. etc

So I picked up a cheap DMR HT the TYT-380 I wrote about before.   It works great, DMR programming is complicated due to the capabilities of DMR.

Unfortunately my house is a Faraday cage, and signals have a hard time making it through the I can only use the radio outside the house.

A technology that has been available for a while and are really maturing are Digital Voice hotspots.   This took me a while to understand the usefulness...because the job it did wasn't really well described.  I have a DV hotspot that has a small radio and connects to the radio can talk to this hotspot which puts my radio on the internet...most Repeater or other hotspots are ALSO on the this hotspot is my connection to the larger radio world.   This hotspot lets me use my DMR radio inside the house.

There are a lot of choices of  'gateway' or 'hotspot' depending on need and what digital radio technology you are using (DMR, DSTAR, FUSION, for a few examples)

So again the problem is I cannot use my DMR in the house.   The solution I chose is the DVMEGA board mounted on a Raspberry Pi.  There are other types...this is simply the one I chose.

I am not going to regurgitate all the well documented steps, I am simply going to list the links I used, and the problems I all cases I made an error/didn't fully understand.

You will need the DVMEGA board...I got the dual band version(from Gigaparts) or.
You need a Raspberry Pi...I have version 3s.
You need an antenna for the DVMEGA board (unless it comes with yours)  I am using a stubby rubber ducky style antenna.

One thing they don't tell you is the DVMEGA is a self contained Arduino powered there will be firmware updates for it...unless you have some kind of special serial programmer (available separately) you will need another method to do the updates...and it involves soldering.   If you do not want to solder, then I would look at a different solution for your DV hotspot.

So my first problem involved the soldering...I did it in my office (I don't have a magnifying glass here, and you are soldering on a SMD component) and apparently I didn't get a good took about a day of battle to troubleshoot that one.

Once the firmware successfully updated, it was all pretty much straight forward.  The second part was getting the software that does the DV stuff onto the Raspberry Pi.  The two ways to do it are to use a standard RPi install and add the new software, or download an already created image...well I did both and downloaded 5 RPi images in the process...that took forever.

BTW the software that does the DMR (and others) is MMDVMHost

For the image, the last one I found (by accident...well hidden) is from DMR-UTAH

I recommend going straight to that one.  You still have to edit a file...but there is a shortcut to all the tools.

The BrandMeister link has the best explanation for the settings...a VERY IMPORTANT SETTING IS Port=/dev/ttyAMA0   There are a variety of other ones in the settings...but this is the only one you want. (one of my attempts used a DSTAR Pi image)

So assuming the firmware update went well, and you are running the software on the do you know if it is working...this also took a while for me to track down, but found simple solutions for that.

First, with the software running on the Pi, when I transmit with my radio, the Terminal window running on the Pi will show the transmission and my callsign...and if it is receiving data it will show those callsigns.   But what do I sound anyone trying to call me?   Found an easy tester for that.

BrandMeister is the voluntary collective for DV through internet...they have some good info (not all, but some)  They also have a couple of good tools.   LastHeard shows all the current connections world can filter the results to your callsign.  Second one is Hoseline , you select a TalkGroup number (note I typed in 3100 in the URL) and it will play the live select the TalkGroup you will be transmitting on, and when you transmit, your audio will come from the webpage.  BTW between all the various moving parts...the audio I heard on the website of other transmission I also heard simultaneously on my HT through the DVMEGA-Pi.

Those two tools really gave me a warm fuzzy that everything on my end was working properly, and the final confirmation was a very positive signal report from an Amateur radio operator who was south of Milan Italy.

The last hard part about this setup is programming the radio...essentially your hotspot is a repeater, so add it to your radio settings like you would add any other DMR repeater.

Some TalkGroups.

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