] So when Clark found the new generation of road sensor,
] Arnu drove out to help investigate further. The pair
] found that, at close range, they could use a handheld
] frequency counter to pick up the wireless signals given
] off by the devices as a car passes. Over the following
] month and half, Clark and Arnu engaged in a kind of
] geocaching game with the Men in Black, systematically
] sniffing out the road sensors with the frequency counter,
] exhuming them, and opening them up. They discovered that
] each device was coded with three-digit identifier that
] could be read off an internal dial, allowing Arnu to make
] a list that correlated each unit's ID number with its GPS
] coordinates, creating a virtual map of a portion of the
] surveillance network surrounding the Groom Lake facility.
] Some of the sensors were miles away from the base.

Walking around arguably the most secret and protected military installion in the US with sensor and GPS equipment, while interfering with US government counter-measures to protect said base is a great way to get shot.

Area 51 hackers dig up trouble