Projects

Radios

Sean Horgan

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I’m experimenting with Long Range (LoRA) radios for some little side projects for the kids:

I want to enable my kids to text their friends without the need to be connected to the full-blown internet on a cell phone. We’ve had great luck with a simple FRS/GMRS walkie-talkie in the neighborhood but the range is limited to about 1/2 miles given the density of the houses and the radios require constant attention & synchronous communication.

I want to know which specific run the kids are skiing on when we are out for the day. I think I can take the GPS coordinates and translate them into a run on a ski mountain using an off-the-shelf LLM.

I want to tinker around with some little DIY projects and I want to justify it as “it’s for the kids” when that’s really a stretch ;-).

I stumbled on meshtastic when looking for walkie talkier alternatives. From

wikipedia⁠

, meshtastic is a decentralized wireless off-grid mesh networking LoRa protocol. The main goal of the project is enabling low-power, long-range communication over unlicensed radio bands. It is designed around exchanging text messages and data in off-grid environments.

There is a lot to like as they have a point-to-point range of a few kilometers and can go ever further when connected to the mesh over many hops across nodes. You can pick up kits for about $30 so they are relatively afford.

Traffic between nodes is encrypted us AES256-CTR & public keys for direct messages. Every meshtastic device comes with 1 primary default channel called “LongFast” with a pre-shared key that enables all devices to communicate with each other. You can also add more channels with a randomly generated key that you can share with others for secure communication. Sharing these keys appears to be pretty easy.

I decided to pick up a few devices to test out before handing them over to the kids. I’ll share more when they’ve had a chance to use them.

Here are some good sites to learn more:

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r/meshtastic⁠

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Meshtastic off-grid radio: Fantastic? Waste of Plastic? Or...⁠

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Early observations

Devices seem to “just work” with minimal configuration out of the box.

It takes about an hour of fooling around the first time with bluetooth connections and strange menus to figure out how to do some basic device management, like change the node name, short name, and turn off location sharing.

Battery life on the H2T is great — it stays running for days with GPS on. The ESP32 is a different story — died overnight when on battery.

There are a lot of nodes in the Boston area with some pretty strong repeater nodes that extend the range to ~20 km with just 3 hops.

If you buy a couple of these to set up and test at home, I recommend pairing each device with a different phone or tablet. Switching between different devices from the same phone is a bit of a pain.

The devices don’t seem to store messages beyond the most recent from another node, so you lose history unless you are paired with a phone that stores the messages. I’m hoping the T-Deck does a better job with message history as that’s a key use case.

Gear

Here’s what I’ve picked up so far:

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H2T - Complete Device: Heltec T114 with GPS running Meshtastic®⁠

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2 Pack ESP32 LoRa V3 Development Board + 1100mAh Battery + Protect Case Set - with 915MHz Antenna and SX1262 Surport WiFi Bluetooth LoRa V3 Devices for Meshtastic Arduino LoRawan IOT⁠

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T-Deck Plus Meshtastic⁠

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LILYGO T-Deck Plus Meshtastic ESP32-S3 LORA-89 915Mhz SX1262 Ulbox GPS White Keyboard 2.8 Inch Display TTGO Development Board with ABS Shell Version⁠

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H2T

I picked this up first Muzi Works as it came fully assembled which would make it easy to check connectivity in my neighborhood. It’s relatively pricey but it has a more power efficient nRF52850 chipset relative to the standard ESP32 chipset in other models. Battery life is important as I want to be able to use this over a weekend without need to recharge.

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ESP32 LoRa v3 dev board

You see these little kits in many videos as they are super simple to put together. I picked up a 2-pack from amazon (

link⁠

) as I wanted to check the range and utility of a $30 device. You can assemble this in about 10 minutes, including the time it takes to flash with the meshtastic firmware.

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T Deck Plus

I really need to hand the kids a device with a keyboard and the best option out there right now is the T Deck from Lily Go. I’m still waiting for this to show up in the mail as they constantly go out of stock.

I bought two of these as I want to give one to one of their friends. I went with one model that has a external antenna mount built in and another that doesn’t. I’ve read that it is easy to modify these in the future so I can add an external antenna if I feel like I need the range.

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T Deck Cases

If the T Deck test goes well with the two units, I’ll probably by a few more for my kids friends and their cousins so they can all chat (securely) on a private channel. I’ll buy some bar bones units and customize the cases so they are a bit more fun for them. There are some great options out there:

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https://www.printables.com/model/741124-lilygo-t-deck-td1-case/comments⁠