Title: GPS: How Does It Work?
Author: Steven Johnston
Article:
The Global Positioning System is a satellite-based navigation
system put into place by the U.S. Department of Defense and is a
network made up of 24 satellites in orbit around the earth. The
satellites orbit the earth at about 12,000 miles, are solar
powered, they transmit a signal of only 50 watts, and travel at
speeds of about 7000 miles per hour. The GPS system was
originally intended for military use only, but during the 1980s
the government decided to allow civilian use. The satellites
make a complete orbit around the earth every 24 hours, and are
spaced equal distances from each other.
Now that we have covered most of the equipment information,
let's talk about what a GPS can do, and why we have such
technology. The GPS system allows for satellite tracking of just
about anything to which you can attach a tracker. The GPS system
is accurate to within about 15 meters from anywhere on earth.
This is some amazing technology, yet it is still relatively new
to the average consumer.
The trick in the operation of this system is the tracking of the
signal, with formulas thrown in to account for the delay in the
transmission of the signal, and atmospheric changes. Since there
are other satellites available to provide a sort of numbers game
for the GPS, a pretty definite location can be determined using
the GPS.
What other pieces of information can be gleaned from the use of
the GPS? Other pieces of information like speed, bearing, track,
trip distance, distance to destination, sunrise and sunset.
That's a pretty amazing piece of work, how did this GPS come to
be in existence?
The Department of Defense originally commissioned the work for a
military purpose only. But during the 1980s it was decided that
the consumer and commercial industry would benefit greatly, and
there was little or no security issues for the military. The
military and civilians alike use two low frequency channels for
signal communication. The civilian GPS transmits on L1 at a
frequency of 1575 MHz. Most of the signal travel by sight, but
will not transmit through solid buildings or structures.
In order to relate this to something the average consumer will
understand and appreciate, OnStar, the communication system that
now comes in many of the automobiles we buy, utilizes technology
like this in order to determine your location in emergency
situations. We don't often stop to think about the GPS system
and the benefits provided to us, until our car won't start and
we push the OnStar button... and this nice voice says, "This is
OnStar, how can we help you.
