Morning all. I have an idea I'd like to discuss for a new open source hardware device.
Yesterday my cat didn't come home all day, and I was worried. He's back now, but I'd love to attach a tracker to him. Actually there are lots of things we might want to track... Tools, equipment, livestock, drones etc.
Problem is, the load capacity of a cat is pretty low, and to be useful the battery will need to last a long time. GPS and cellular modems are right out, and in any case would be expensive. Fortunately there are new wireless technologies that fill this need, in particular LoRa.
LoRa is a low power, long range wireless networking system that anyone can set up. You can install your own LoRa base stations in your house, or use commercial city wide ones. It's very low bandwidth, but you don't need much for this application.
So my idea is to build a tag that can be attached to a collar or a tool, about the size of the CR2032 battery. In fact it would have a 2032 coin cell in it. I estimate that transmitting once every 15 minutes on LoRa would give around 2 years battery life if carefully optimised. I'd probably look at something like an SX1272 transceiver, although a cheaper option might exist since it only needs to transmit (no RX). Some kind of micro will be needed to manage transmissions. The main difficulties will be power management (CR2032 will need capacitor backup I think, probably something specialist to fit the form factor) and designing a suitable antenna.
Users of the system will have their own LoRa base stations in their homes and businesses, connected to the internet. Commercial network use might be an option too. The base stations will simply listen for pings from tags, which will be nothing more than a serial number, and report them to a cloud service along with the signal strength. That won't give a precise location, but it will give an idea of roughly where something is and give the owner some confidence that it hasn't got lost or stolen, or somewhere to start looking.
I'd love to hear some feedback and comments on this idea. I think the main problem will be mechanical, making something that is IP68 and performs reasonably well. It might be a question of having disposable tags so that they can be sealed permanently, rather than replaceable batteries, but then you have shelf life issues or a need for an activation switch.