Meshtastic is a really exciting project which uses LoRa to send short text messages (and metadata) extremely long distances with incredibly low-powered and tiny hardware.
"Tiny" should get your attention there. Yes, that means small antennas. The Heltec V3 has an integrated antenna which is just a length of wire, about 5-6cm long. In terms of range, I'm in regular contact with nodes 70 miles away.
That range grows enormously as soon as you throw a decent matched antenna its way. It really is pretty nuts.
The technology which powers Meshtastic is known as LoRa. Through a bit of RF magic called chirp spread-spectrum, it is said to be detectable and readable even below the noise floor . On a spectrum analyser, it looks like this.
A symbol can be a 'chirp up', frequency going from low to high - or 'chirp down', frequency going from high to low, as well as phase modulation. Link Labs has a decent writeup of how it works which pushes their hardware pretty hard. Still, it's a decent summary of the tech and RF mechanics behind LoRa, and includes a highly technical video if you want to really get your hands dirty.
You'll need a node. There are many options, but there are three that I'd recommend.
The Heltec V3 is dirt cheap and has far better RF performance than it has any right to. You can pick one up on Amazon UK for £27. It might be a clone - I'm not certain - but it'll do the job just as well. It has a small OLED display, but you're going to do most of your interacting with it using the mobile app, desktop app, or Web interface anyway.
