“LoRa is able to work below the noise floor–this is completely at odds with what you’ll have been taught”

Over the next few issues I want to talk about LoRa communication. Short for “long range”, it’s a type of low-cost, low-power, extreme-range radio. I’ll go through some use cases later, but for now just imagine that you’re a farmer and your land stretches across a valley. Your farmhouse is on one side and you have a flock/herd/whatever of animals and a shelter on the other side, about 1km away. You want to know the temperature in the shelter (if it’s too cold, you’ll need to bring the animals back to the farm).

The first thing you might think of is some kind of Wi-Fi-based temperature sensor, relaying back to the farm. Perhaps something like one of the Cricket boards I wrote about in 2020 (see issue 312, p113); there’s more news about that towards the end of this column. Obviously, you can’t transmit a normal Wi-Fi signal across 1km, so you’ll need something like an Ubiquiti Nano Beam to create a point-to-point connection. There’s just one problem: the shelter doesn’t have any power. Any long-range Wi-Fi kit is likely to need mains power.

This is where LoRa comes in. A battery-powered sensor will easily cross that 1km valley, and as I’ll show when I come on to some of the kit that you might play with, there are relatively cheap sensors that will last for ten years on a single battery.