John's Musings


Yeah, Me Neither

DMR Radio

So I get my Ham license and originally it was.............I just wanted the license, I don't actually want to transmit. Then I found out I could hit a local repeater with a small inexpensive walkie talkie so I began transmitting. Then one day I am camping out in the woods and the guy next to me comes and tells me he's a Ham and starts teaching me about DMR radio. DMR stands for Digital Mobile Radio and the best way to describe it is that it is the system of walkies and mobile radios the gigantic company near you uses or what your local police are using. You might hear a commercial on the radio for Motorola MOTOTRBO radios for your business.


One of the joys of DMR radio is that the popular frequencies it uses are covered by the lowest class of amateur radio operator meaning anyone with a Technician Class license can play. Secondly, in the event that you cannot reach a physical radio repeater because you are out of range such as is that case in backwater New Bern, NC you can enter the system from the Internet via a hotspot.


So basically the lowest class Technician can buy a cheap DMR capable radio such as the TYT MD-380



Don't be fooled by the naysayers out there. Although the MD-380 is Chinese made and inexpensive it is more than adequate to get you started on DMR radio.


One of the very cool things about this radio is that you can upload Open Source Firmware to it which gives you a lot more capability. The firmware is called MD380tools and is a super cool addition to the radio. The downside is that it voids the warranty. Yeah, right. If the radio isn't working correctly flash back to factory firmware and send it back.


It is possible that this cheap radio can in the future do P25, Fusion, and D-Star. I believe developers are working on adding these capabilities.






Anyway this radio only has a few watts of power so if you aren't living under a repeater you have to access the DMR network via a HotSpot. Before you can do any of this you must of course have a Ham Radio License and you must receive a free Unique Radio ID from DMR-Marc.net Look at the top toolbar for "Register ID" then fill out the request form and wait a day or so.




Now you need a hotspot. There are a few different directions to go with this and for the most part it is going to cost you $200 or so. Think about this. Picture in your mind an old Ham Radio guy and his radio shack then imagine how much all that glorious gear cost Old Mr. Ham. I'm telling you that you can talk to the whole wide world for about $300. Let's keep it in perspective.


The most popular (I guess) hotspot is the SharkRF OpenSpot.




You literally plug this in to ethernet in your home and do a few configurations on the web based config page of the appliance and you are talking to the world. I'm not getting into configuration in this page but it isn't difficult at all. Put in your call sign, your DMarc ID, set two or three other variables. Bang. Done.


OpenSpot does DMR, D-Star, and Fusion so even if your cheap Chinese radio doesn't......you can still talk to these protocols via the OpenSpot. How cool is that? All you do is set a simplex (same frequency receive and transmit) channel up on your radio.


The missing link here is P25 radio. I personally am not into it but P25 is a popular protocol. To get P25 requires you to get another radio and another hotspot.





One of the more popular ones (but certainly not the only one) that does P25 is the DVMega. For it you need a small board computer (there are several variants for several computers, this is for Raspberry Pi). So then you need a Raspberry Pi. Then you need to install an operating system on said Raspberry Pi.



The most popular one (and again, not the only one) is Pi-Star Once Pi-Star is installed you plug in the DVMega which then MIGHT need a firmware update so you can do P-25. The firmware update is not for the faint of heart and could involve soldering in one instance, or removal of the IC chip and placing it into an Arduino Uno R3 and flashing it. This of course means you have to own an Arduino R3 Uno (about $25). I'm a geek. I already have one.


Anyway after buying a Pi, installing Pi-Star and flashing the DVMega then you can configure Pi-Star. It is a lot harder to set up than the SharkRF OpenSpot but that's not saying much. It's still not that hard.





Here's my config. (when I took this screenshot I didn't actually have the DVMega installed. It is still in the mail. That is why P-25 is grayed out).





Anyway by using a hotspot I can key up on a low power walkie talkie and use one of many talk groups to talk literally around the block or around the world. Talkgroups and configuration and something called the Brandmeister networks are a blog for another day!





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