Findphone: Locate a nearby Bluetooth device by signal strength

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: https://github.com/agittins/bermuda

20 years ago I meant to write something like this, but so friends could find each other nearby in places like clubs.

I thought unless an android or iPhone is beaconing, it only broadcasts ble on device wake?

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.

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 https://news.ycombinator.com/item?id=49215786 215 comments ?

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

Bluetooth now has something that does this more accurately on a protocol level: https://www.bluetooth.com/learn-about-bluetooth/feature-enha...

Seems to be macOS only.

Now turn it into a pervert-glasses detector and tracker

Make your phone alert when one walks into a room within several meters