Make: Volume 91

parts of the radio spectrum used by commercial

wireless surveillance devices (Figure

E

).

DETECTING MAGNETIC FIELDS

At first glance, the magnetic sensor on the

K18 may appear pretty useless. But it actually

serves an interesting role. Many devices, such

as GPS trackers, don’t broadcast RF, they only

receive signals from satellites. They serve as

data loggers, storing the information on-device,

and are physically retrieved rather than remotely

accessed. An RF detector is useless for finding

them. These devices are often hidden on the

chassis of vehicles to track their drivers and

include a magnetic base for easy mounting and

removal.

Ther ...