This has been promoted on social media as a solution for backup communications. One of the first things to understand is that, although the ads often show devices that look like walkie-talkies, they are not actually walkie-talkies. Devices with voice capability are often FRS radios, but the mesh network itself does not have enough bandwidth to carry voice signals. These devices are text-only. It is also frequently claimed that they are “off-grid.” That is not entirely accurate. What they actually do is create a separate, local network between the units rather than relying on an existing communications grid.
Although we are already aware of the limitations of the technology, I purchased several units for testing. Since these are radios, we can estimate their range and identify likely gaps in coverage, but we still wanted to give them a fair opportunity.
The first units turned out to be experimenter boards placed inside 3D-printed cases. While assembly itself does not concern me, I discovered that the boards did not fit properly in the cases, so I had to return them.
For the second attempt, I purchased pre-assembled units (Lillygo T-Deck Pro), but I could not get the Bluetooth connection to work. It turned out that the software version they shipped with had a bug affecting Bluetooth functionality, so I had to install a different version. Overall, the setup process was more difficult than I would normally expect, and I suspect many users would have given up.
We chose Meshtastic because it is better suited for creating ad hoc relay networks in mobile scenarios. MeshCore, by contrast, depends more on a formal repeater infrastructure, and I was unable to locate an available repeater.
The first limitation observed is the device’s poor indoor signal reception. This is not unexpected for low-power devices operating in the 915 MHz frequency range. It is a cheap unit and can’t be expected to have the same capability as professional designs. Outdoors, however, it does successfully receive messages. Meshtastic also has a hop limit, so some distance limitations are expected. Even so, I have received messages from across Los Angeles and into Orange County.
Update: I took the Meshtastic device with me on a hike into the mountains. It actually surprised me at the campground where I started, Crystal Lake, by joining a local cluster of nodes. Those nodes may have been located at nearby residences, cabins, vehicles, or campsites. I’m not sure whether the signal reached beyond that area, but it did seem capable of passing messages within the campground.
The issue began once I started up the mountain. About a half mile outside of camp, the device lost all connections and never reconnected. For the rest of the hike, my NexEdge and ham radios continued to work. My cell phone connected in some areas, but the Meshtastic device did not. This is not unexpected. A low power 915 MHz radio is affected by obstructions and distances. If the signal can’t make it to the next node, it can’t be relayed.
Really this leads in to a definition of terms. Commonly these are advertised as working “Off Grid”, but that is not really true. Radios VHF, UHF and up are significantly affected by obstacles. To work around this limitation requires some kind of support infrastructure. That may be a repeater, or access to a network, which is itself a “grid”. While they may not be dependent on the cell phone network, there is still a need for the message to be relayed, so there needs to be other units within radio range.
There may be a use for this device in areas where there are enough of them in use within range of the radios signals such as a suburban of semi rural area. They do not reach deep in to the forest or areas that are separated by large gaps.