Data Hacking

Hacking Geocaching
If a gadget or device penetrates the consumer market well enough, it will
eventually be incorporated into some sort of game activity. GPS is no
different, and because GPS can be used to pinpoint locations, making
a game out of getting to locations marked by others was an obvious evolution.
Before any games could spawn from GPS, however, accuracy had to
increase. This chapter examines geocaching, after a little history of the
accuracy of GPS.
GPS Accuracy
For years, GPS wasn’t available to the likes of you and me; it was purely
military-only equipment. Back then, GPS receivers were too expensive
for most people. The price eventually dropped, but GPS still had limited
appeal, and its main users were sailors and hikers. What GPS needed to
become popular was an injection of accuracy, and this is exactly what happened
on May 1, 2000, when former President Bill Clinton removed the
deliberate error contained in the GPS signal up until then.
This error, known as Selective Availability (SA), degraded the signal that
consumer units could pick up. Selective Availability meant that 95percent
of the time the position shown on a GPS receiver was supposed to be off
by 100 yards or less, while for the other 5 percent of the time the error
might be even greater, or there might not be any error at all! You never
knew. Basically, the 100-yard error meant that you could only reliably
plot your position within a circle 200 yards in diameter, as shown in
Figure 11-1.
chapter
in this chapter
˛ What is geocaching?
˛ A typical geocaching
trip
˛ Tips on finding a
geocache
˛ How to power your
electronic devices
while on the move
˛ Protecting your gear
while on the move