A Multi-Mode Digital Voice Modem (MMDVM) Hotspot is built on a Raspberry Pi, sometimes called a Pi-Star.
It is a small radio, that has built in WiFi and Bluetooth. It is available as both a simplex (more common) or duplex device as well as in VHF or UHF, or even dual band configurations.
It connects to your router, by WiFi or with a CAT-5 cable, depending on the model. You can use a DMR, D-STAR (Icom) or YSF (Yaesu Fusion) radio to connect to it and then to Wires-X “rooms,” D-STAR reflectors and repeaters as well as DMR talkgroups on several different DMR networks (Brandmeister, TGIF, DMR+ and more). You can configure the MMDVM to convert from your Fusion radio to a DMR talkgroup, DMR to Fusion and several other combinations (click here for the instructions to use a Yaesu Fusion radio with your MMDVM).
There are a variety of different MMDVM hotspots available, as kits or complete. The one pictured left is the AURSINC and available on Amazon for about $190. There are more expensive versions, such as those with dual band (VHF & UHF) but I suggest that you get a UHF such as the AURSINC.
Another option, if you have the budget, is the Zumspot. It has a large display so you can see what talkgroup and who is talking without using the Pi-Star dashboard on your laptop or tablet. It is about $250 and available from Ham Radio Outlet (HRO), I’ve not found it on Amazon yet.
Setup
When you get your MMDVM you will need to do some setup, in most instances you can do this from the pi-star dashboard. I just re-did mine from scratch as I had an old version software (version 3) and it didn’t do the automatic updates that version 4 does. The site I used to take me through the steps was here and I found it very easy to follow (with some pauses in the video). Most of the time your new device will come with the current software (image) on the SD card and you will not need to re-image the SD card. You will need to set it up on your WiFi (or multiple WiFi’s).
Read all this page before attempting setup following the video. There are some parts of the video that talk to DMR settings and I’ve some screen shots and information below that might help.
The one step that I found didn’t work was using the WiFi builder on the Pi-Star dashboard. What I did was follow the notes here. That allows you to connect your laptop directly to the MMDVM using the built in WiFi. From there you can use the configuration menu directly to complete the next setup steps including adding your WiFi. The Youtube video steps you through those steps and I’m not going to try and repeat them here when there is already a very good video!
Once set up I use a battery pack and put mine in a waterproof box so that I can take it anywhere. In my case it is configured to use my MiFi (a portable WiFi), which I can place inside the box. Both the MiFi and MMDVM run off a battery with USB connections. You can set the MMDVM to work on multiple internet WiFi’s, including your cell phone hotspot, so it will connect to the one you are nearest. I suggest you only do this after you have got use to using it.
The battery pack in the pictures is a Ubiolabs Power Bank, 10,000mAh, 37Wh (Watt hours) pack. It has a USB-C and USB-A outputs (both 5V/2.4A 12W). It will run the MMDVM for 3-4 days depending on the amount of use.
Dashboard
To start with I suggest you only set the device to connect to a DMR network (if you have a DMR radio, I’ll show cross mode set up on another page), as the Youtube video shows.
When you have set up the MMDVM you will program channels in your radio (low power) for each talk group (TG) you want to connect to. When you key up your radio the MMDVM will connect to that TG. One the display above at the bottom you will see the current Local RF Activity. In this example it shows that I keyed up at 10:49:42 and connected to TG 29185. So same frequency, same frequency, color code, and time slot (usually always 2), just change the talkgroup.
In the panel above, Gateway Activity, it shows that prior to connecting to TG 29185 I was connected to TG 310847 and all the transmissions received on that TG that the MMDVM re-transmitted.
Configuration
In the configuration dashboard the only option you should have on is the DMR mode if you followed the Youtube video. As you can see you have the option to enable D-Star, to connect to any of the D-Star repeaters or reflectors, as well as YSF mode which is the Fusion Wires-X connection. Again, I strongly suggest you leave all these options off until you are more experienced with using the MMDVM.
DMR Systems
If you scroll down on the configuration page you will come to the DMR Configuration section. This is where you choose what DMR network you are connected to. If you are going to use Brandmeister then drop down to BM_3102 and select one of the US ones. If you are going to connect to the TGIF network then select TGIF_Network.
Brandmeister Network Security
Brandmeister has added additional security to their network. To access with a MMDVM you will need to create a user ID and login. Once you submit it takes about 12-24 hours for them to verify. You set your password up under my devices and then you will be able to connect.
Stump Knocker
The TGIF DMR network allows groups to request a talk group. If you go to the TGIF web page dashboard you will see active or “last heard” talk groups. If you go to the talk group list page and type in Stump Knocker in the search box you will see talk group ID 29185. Set this up in your radio as a channel.
We hold a regular net on Monday evenings, 2000hrs (8pm) eastern.
Chris is usually on. Even when there isn’t a net you can usually find me listening and Chris is if he’s in his office.
Your Own TG
If you have your own MAG or family group who all have at least a Technician class ham license you can request your own TG on the TGIF network. If you have a portable set up, as I have shown above, you can set your portable up and communicate with anyone on “your” TG from anywhere you have an internet (cellular or WiFi) connection.
Another alternative is to use your radio ID as a talkgroup. Not commonly known but you can ‘direct connect’ to any repeater or any device with a DMR ID. Therefore if several of you use one of your DMR ID’s you would all be talking on the same talkgroup. With this option your talkgroup is not listed on the DMR list, i.e., on the Brandmeister or TGIF table of talkgroups. It will show up on the ‘last heard’ lists but it is doubtful that anyone would really pick up on it as those lists scroll fast and I doubt anyone would really notice that several people are using the same talkgroup, because all that shows is the number.
Now this isn’t secure, as encryption isn’t “legal” under FCC rules. So anyone with the TG ID could set it up and listen. Now if you have your MMDVM set up on a TG you will see when anyone keys up to connect to it. You don’t need to have a browser to operate the MMDVM. Once it is set up on the DMR network you want to use all TG changes are done with your radio. If you want to you can use the browser on your cell phone or a tablet to see the dashboard.
For more information on secure communications see this page.