Sorry, extraordinarily sensitive sensors on drones and
elsewhere, can be used to detect and classify direction,
type, frequency, duration, strength, etc. of a wide range
of electromagnetic signals.
You can buy a relatively cheap meter from Amazon that will
detecct such things and even identify cell towers, wifi routers
and hot spots, microwave ovens, plus cell and wifi signals
from phones and more.
WIFI sources can already provide a means for tracking to
within inches. Check how the MTA is tracking trains with
a company called Piper.
I mentioned a trio of drones, because triangulation is
used to deduce specific locations, mostly by comparing
signal strengths/directions from multiple detectors.
Same can be done with BLE, once you get close enough to
detect it. Plenty such tech exists, awaiting only our
consent for its widespread use against us.
“Check how the MTA is tracking trains with
a company called Piper.”
Not related to GPS.
“I mentioned a trio of drones, because triangulation is
used to deduce specific locations, mostly by comparing
signal strengths/directions from multiple detectors.”
Relative, not absolute positions