When I lost my phone I put in one earbud and walked around the area listening for the connection sound.<p>Turns out it wasn't useful because someone else had taken it to lost and found within a few minutes of me losing it, before I knew I'd lost it. But it was a good idea.
If you have multiple fixed BLE receivers, you can do full trilateration. This project integrates into Home Assistant using HA proxy BLE receivers to track phones moving around in your house: <a href="https://github.com/agittins/bermuda" rel="nofollow">https://github.com/agittins/bermuda</a>
I thought unless an android or iPhone is beaconing, it only broadcasts ble on device wake?<p>Maybe I'm misremembering, but for example my esphome proxies in HA will show nothing for ages at night while my phone isn't being interacted with.<p>If the phone is lost, it's probably not super awake lol
Post inspired by "Lost my phone at the office. Claude suggested tracking Bluetooth signal strength" 07.aug.2026 <a href="https://news.ycombinator.com/item?id=49215786">https://news.ycombinator.com/item?id=49215786</a> 215 comments ?
20 years ago I meant to write something like this, but so friends could find each other nearby in places like clubs.
Bluetooth now has something that does this more accurately on a protocol level: <a href="https://www.bluetooth.com/learn-about-bluetooth/feature-enhancements/channel-sounding/" rel="nofollow">https://www.bluetooth.com/learn-about-bluetooth/feature-enha...</a>
Weirdly Apple seems to have something like this built-in for finding an apple TV remote - but the same flow doesn't appear to be launchable for any other device
It works for newer AirTags as well, this isn't BLE based but Ultra Wideband.<p>That's an entirely different technology, and if you look at it from an RF lens, a highly impressive one.
Seems to be macOS only.
Now turn it into a pervert-glasses detector and tracker<p>Make your phone alert when one walks into a room within several meters
Already exists, most of them advertise via BLE so you just need to watch for their adverts: <a href="https://play.google.com/store/apps/details?id=ch.pocketpc.nearbyglasses&hl=en_US&pli=1">https://play.google.com/store/apps/details?id=ch.pocketpc.ne...</a>