In order to fully appreciate the various possibilities that the GPS
technology offers consumers, one first needs to be aware of exactly what the
applications and benefits are of this important technology.
This article discusses what GPS is, how it works, and what current uses
have been found for it that can be acquired on the general market. Of
course, there are new applications being developed all the time, as the
technological environment becomes more advanced.
What is GPS?
Originally conceived as a navigation aid for the military, the Global
Positioning System, or GPS, has since grown from relatively humble
beginnings as different supporting technologies have been developed, some of
which are within reach of consumer budgets.
All that GPS does is provide a set of coordinates which represent the
location of the GPS unit with respect to it’s latitude, longitude and
elevation on planet Earth. It also provides time, which is as accurate as
that given by an atomic clock.
The actual application of the GPS technology is what leads to such things
as navigation systems, GPS tracking devices, GPS surveying and GPS mapping.
GPS in itself does not provide any functionality beyond being able to
receive satellite signals and calculate position information. But it does
that very well!
How it Works
The actual principal of GPS is very easy to appreciate, since it produces
similar results to traditional "triangulation" although GPS does
not use angles. If one imagines an orienteer needing to locate themselves on
a map, they first need to be able to find at least three points that they
recognize in the real world, which allows them to pinpoint their location on
the map.
They can then measure, using a compass, the azimuth (This is the
direction of a celestial object, measured clockwise around the observer's
horizon from north) that would be needed to take them from the point on the
map to their current position. A line is then drawn from each of the three
points, and where the three lines meet is where they are on the map.
Translating this into the GPS world, we can replace the known points with
satellites, and the azimuth with time taken for a signal to travel from each
of the known points to the GPS receiver. This enables the system to work out
roughly where it is located, it is where the circles representing the
distance from the satellite, calculated on the basis of the travel time of
the signal, intersect.
Of course, this requires that the GPS locator has the same coordinated
time as the satellites, which have atomic clocks on board. To do this, it
cross checks the intersection of the three circles with a fourth circle,
which it acquires from another satellite.
If the four circles no longer intersect at the same point, then the GPS
system knows that there is an error in it’s clock, and can adjust it by
finding one common value (one second, half a second and so on) that can be
applied to the three initial signals which would cause the circles to
intersect in the same place.
Behind the scenes, there are also many complex calculations taking place
which enable the system to compensate for atmospheric distortion of the
signals, and so forth, but the principle remains the same.
Tracking Devices
One of the easiest applications to consider is the simple GPS tracking
device; which combines the possibility to locate itself with associated
communication technologies such as radio transmission and telephony.
Tracking is useful because it enables a central tracking center to
monitor the position of several vehicles or people, in real time, without
them needing to relay that information explicitly. This can include
children, criminals, police, emergency vehicles or military applications,
and many others.
The tracing devices themselves come in different flavors. They will
always contain a GPS receiver, and GPS software, along with some way of
transmitting the resulting coordinates. GPS watches, for example, tend to
use radio waves to transmit their location to a tracking center, while GPS
phones use existing cell phone technology.
The tracking center can then use that information for co-ordination or
alert services. One application in the field is to allow anxious parents to
locate their children by calling the tracking station – mainly for their
peace of mind.
GPS vehicle tracking is also used to locate stolen cars, or provide
services to the driver such as locating the nearest gas station. Police can
also benefit from using GPS tracing devices to ensure that parolees do not
violate curfew, and to locate them if they do.
Navigation Systems
Once we know our location, we can, of course, find out where we are on a
map, and GPS mapping and navigation is perhaps the most well-known of all
the applications of GPS. Using the GPS coordinates, appropriate software can
perform all manner of tasks, from locating the unit, to finding a route from
A to B, or dynamically selecting the best route in real time.
These systems need to work with map data, which does not form part of the
GPS system, but is one of the associated technologies that we spoke of in
the introduction to this article. The availability of high powered computers
in small, portable packages has lead to a variety of solutions which
combines maps with location information to enable the user to navigate.
One of the first such applications was the car navigation system, which
allows drivers to receive navigation instructions without taking their eyes
off the road, via voice commands.
Then there are handheld GPS units, such as those from Garmin, Magellan
and a dozen other manufacturers, which are commonly used by those involved
in outdoor pursuits, and only provide limited information such as the
location, and possibly store GPS waypoints. A waypoint being a location that
is kept in memory so that the unit can retrace the same path at a later
time.
More advanced versions include aviation GPS systems, which offer specific
features for those flying aircraft, and marine GPS systems which offer
information pertaining to marine channels, and tide times, etc.
These last two require maps and mapping software which differ vastly from
traditional GPS solutions, and as such can often be augmented with other
packages designed to allow the user to import paper maps or charts. The
mapsource software is one such industry standard package.
There are even GPS solutions for use on the golf course. Golf GPS systems
help the player to calculate the distance from the tee to the pin, or to
know exactly where they are with relation to features such as hidden
bunkers, water hazards or greens. Again, specific maps are needed for such
applications.
About the Author:
Guy Lecky Thompson is a successful freelance writer offering guidance and
suggestions for consumers regarding GPS
tracking, GPS,
GPS maps and tracking
devices. His many articles give information and tips to help people save
money and make smarter decisions.
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