Mesh Radio Communications for Team Operations
How far apart can team members operate using mesh radio networks?
Back on the Wire
I was on the Camino de Santiago during the several week hiatus in the series on mesh radios and mesh radio networks. The Camino de Santiago reinforced for me the need for non-cellular communications. Our route took us through rural northern Spain and we often had no cellular coverage at all. You are not “prepared” unless you have communications capability that depends only on resources that you control. Mesh radios and mesh radio networks can provide that capability.
In my last article, I showed pictures of the mesh radios that I built. Looking back at that article with a few weeks remove; I didn’t make it clear enough that these radios came as a bag of parts. These radios came as a bag of parts and I put them together. Then, I installed the software that makes them work.
I did not find it difficult to put the parts together but I have a technical background. Early in life, I trained as an electronics technician and I was a Special Forces communications specialist (MOS 18E). I was a technician and a printed circuit board designer at IBM. My background is deeply technical and that contributed to “putting the parts together was not difficult.”
If you are coming from a less technical background, then the process may go more slowly for you. All the knowledge and techniques you need to assemble the radios are available online. Read all the documentation. I bought my hardware from RAK Wireless and I give them high marks for documentation. The Meshtastic documentation is also excellent. It will make the process much easier if you use supported hardware (https://meshtastic.org/docs/hardware/).
Mesh Radio Network Range Testing
I did two basic types of range testing with my radios. I tested the absolute range using the Meshtastic range test function.
For my testing, I used the Meshtastic radios that I built. I controlled the radios with the iOS Meshtastic app. This is not a rigorous range test. You simply set one radio (the sender) to transmit using the range test setting and then move the second radio (the receiver) away from the sender until you lose contact.
The maximum range that I achieved in this simple test was 2.5 miles. That was in a hilly and very (electronically) noisy environment using small “rubber duckie” antennas. I think that much greater ranges are possible.
Having said that, a separation of 2.5 miles between team members using these radios is a very practical working distance for team operations. In most team operations, you’ll have a team member much closer than that. Using the 2.5 miles as a practical working maximum range means that you could have a team spread across several linear miles of terrain remaining in contact with each other. A four person team could relay messages for ten linear miles.
The second range test I did was practical testing in terrain. My aim here was to validate that the mesh radios would work to relay messages around and over practical terrain obstacles. For this testing, I went to the Sawmill Tactical Training Center in Laurens, SC ( https://www.sawmillttc.com/ ).
I tested the radios communicating from the Sawmill office to the river. See the picture at the top of the article. Using handheld FM radios (FRS or GMRS), I have had difficulty maintaining communications from the office down to the river because of terrain and vegetation masking.
I powered all the radios off until I arrived at the Sawmill. Then, I set up a mesh radio (R1) at the Sawmill office. I powered on a second radio (R2) and walked down the hill testing all the way. I did not initially power on the third radio.
I tested the link between Radio 1 (R1) and Radio 2 (R2) as I went down the hill. I went behind berms and into the ravines between the long range berms. The radios never lost comm’s. FRS and GMRS radios (low powered FM radios) have struggled with terrain masking at the Sawmill. These Meshtastic radios using a SEMTECH Long Range (LoRa) transceiver have a very low power output (about 0.16 watts of power or +22 dBm.) Using that low power transmitter, they can reach greater distances than FM radios that have much more power. For comparison, FRS radios transmit between 0.5 watts and 2.0 watts of power. The secret that makes Meshtastic radios reach much longer distances is the LoRa modulation technique (Chirp Spread Spectrum) which we will cover in a future article.
Then, I set R2 up on top of a gravel pile and powered on Radio 3 (R3). I went down to the river and tested the link from R3 through R2 to R1. It communicated flawlessly with R2 relaying messages between R3 and R1. I used the radio logs to verify that R2 was relaying the messages instead of R1 communicating directly with R1.
This was not a rigorous test and it did not exercise the distance capabilities of LoRa radios. I’m confident that I could have stretched the radios out for much greater distances. My goal here was to validate the relaying and to validate practical comm’s using LoRa and Meshtastic in realistic terrain.
Conclusion
These radios (as built with RAK Wireless radios using a SEMTECH transceiver) provide a practical communications capability in terrain. They are resistant to terrain masking. The range is sufficient to support team operations in most circumstances.
Concurrently with this test, I did a battery life test. I’ll cover that in more detail in a future article. Battery life depends on quite a few variables but I found the battery life (with the 850 mAh batteries I used) to be sufficient for team operations. I haven’t tested the solar panels yet but they show promise for near “eternal” battery life.
Caveats
All radio communications depend on the antenna. I built these radios with an external “rubber duckie” antenna. Different antennas will change the maximum range achievable.
Your build may be different. As you plan your build, plan to include hardware which helps increase range.
As built (by me), these radios are not rugged enough for team operations. Ruggedizing a radio is a craft unto itself. It is certainly possible to ruggedize them enough for team operations but I have not done that (yet).
Terrain is a big factor in radio range. I was impressed with the ability of these radio to overcome terrain masking but your terrain may be more difficult.
I write about AR-15’s and AR-10’s too. You can get a copy of my book “Understanding the AR-15 and AR-10” on Amazon.
Click here to buy the book: Understanding the AR-15 and AR-10