There are button-sized Bluetooth GPS loggers. They can record a GPS track, and you can later download the data from them. Since it's freaking GPS, it automatically has timestamps, so it's easy to correlate with other activity.
As a bonus, I think it should be possible to connect them directly with the phone.
BRB, I think I have a ESP-based Tiny Arudino somewhere...
Actually, you gave me an idea!
There are button-sized Bluetooth GPS loggers. They can record a GPS track, and you can later download the data from them. Since it's freaking GPS, it automatically has timestamps, so it's easy to correlate with other activity.
As a bonus, I think it should be possible to connect them directly with the phone.
BRB, I think I have a ESP-based Tiny Arudino somewhere...