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 its 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 its 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.
