The GPS (Global Positioning System) has been fully functional for nearly two decades. GPS consists of 27 satellites positioned in a medium earth orbit. A satellite is considered to be in medium earth orbit when it is 35,000 kilometers above the Earth's surface, roughly 22,000 miles. The first experimental satellite was launched in 1972. It was not until 1995, 23 years after the launch of the first experimental satellite, that GPS bore fruit as a fully function satellite tracking system. Even then the system was restricted to military and airline industry use.

Once GPS was fully functional both the military and civilian implications were quickly recognized. In 1996, then President, Bill Clinton, opened the system to civilian uses as well as military uses. Due to limitations early civilian GPS was not very reliable and so its wide spread use had been severely limited. In 1998 and again in 2004 extra civilian signals were added to GPS. The net affect of the added civilian signals was that the quality and accuracy of the data were raised to a level that civilian GPS has now become a marketable product and service. Since 2004 GPS as a market technology has realized a boom in demand with no end in potential growth in site.

How GPS Technology Works

The 27 satellites that are collectively known as the Global Positioning System have flight patterns that make four satellites available to a GPS receiver at any time any where in the world. A GPS receiver must be able to contact and communicate with a minimum of 4 satellites to be able to calculate minimally qualified location data. The larger the number of satellites a GPS receiver can contact the better it will be able to calculate a location.

In order to triangulate a geographic position a GPS receiver calculates the time that it takes for the signal of the GPS satellite to reach the GPS receiver. From this data the GPS unit is able to calculate the distance to each satellite. The time distance information is then used by the mapping software on the GPS receiver unit to determine an exact location on earth.

Satellite signal degradation from both natural and man made obstructions can affect how accurate a GPS unit is. This is why GPS units will try to contact as many GPS satellites as possible. The more satellites the GPS unit is able to contact the more accurate the location.

Uses Of GPS

The purpose of GPS technology has not changed much over the last 30 years. Its primary purpose is still to as precisely as possible pinpoint a location anywhere on Earth. How GPS technology is used has not truly changed either. It is used for two primary functions tracking and navigation.

Growth in GPS technology has not come because of changes in use but because of an increase in signal quality, decrease in component costs of a GPS unit, increase in the quality and sophistication of mapping software, the bundling of GPS units with other services, and more sophisticated marketing to a broader segment of the population.

Today GPS units large and small can be found in airplanes, cars, attached to motorcycles, in cell phones, PDAs and hidden in freight to protect from theft.The shrinking of GPS unit component sizes has enabled the use of GPS to be limited only by your imagination.