[mad_as_he$$]

Yup, a droid tied into the vehicle power system and you can access the position for weeks or months. Way more concealable than the current Fed stuff. For many years now the chips have been very small, it is all the stuff needed to make them work and talk to the outside world that takes up space. I also like it in the movies when they are 100 miles from anywhere and the quarter size unit is sending data back to them. lol...

[Myrddin]

I’ve used some quarter size sensors running ANT protocol
and scavenging power from vibration of a piezo
electric device. The sensor sends brake shoe pressure
readings that are captured by a receiver that is
typically within 100 feet of the device. Nothing as
power hungry as a GPS receiver or cell phone trnaceiver.