You may have heard of GPS at some point; it is just one of the many abbreviations that are used so frequently nowadays even though their meaning is by far not clear to everyone. You might also know that GPS stands for “global positioning system” and that it is pretty recent and useful technology. But do you know exactly how it works and what its uses are? If not, you might as well read this article to the end, because it will attempt to explain as plainly as possible what GPS is and what its uses are.

What is GPS?

Basically and put very simply, GPS works with the help of 24 satellites. A GPS receiver calculates where exactly it is by figuring out at what distance it is from a number of those satellites. Each GPS satellite circles the earth twice a day. Information from all of the 24 satellites might not be needed at all times; sometimes the receiver will be able to figure out its location based on its distance from just three or four of them. However, as of March 2008, there are 31 satellites around to support the GPS system. While the extra 7 of those are not strictly necessary, they are used to make GPS receiver measurements even more accurate by sending sometimes redundant information. Also, should one or more satellites fail, the system would still be available thanks to the larger number of satellites. GPS works 24 hours a day, independently of the location of the person, the weather conditions or other external circumstances. The position of the satellites in space needs to be controlled in order to ensure the accuracy of GPS. The instruments used for locating the satellites are carefully monitored at all times. Also, it is important that the time the signals sent from the satellites take to reach the earth is controlled for so that it does not influence the system. Originally, global positioning system worked with only five satellites, was by far less accurate and its purpose was meant to be helping the US army. The first satellite navigation system was successfully tested in 1960. Up until 2000, high GPS accuracy was still reserved for the US army; when this was stopped, the accuracy available for the average civilian was increased from about 100 meters to about 20 meters. Nowadays, GPS is available to virtually everyone and most cell phones have an integrated GPS receiver. But why?

How is it useful on a cell phone?

Imagine you are on a highway in the middle of nowhere in the United States of America. The car in front of you gets off track for whatever reason; spins around and finally comes to a halt. You pull over and open the other car’s door, only to find that one window is broken and the driver appears to be unconscious. As you dial 911 you suddenly realize you have no idea where you are. Luckily enough, the E911 program requires every cell phone to call 911 should be able to be tracked within 50 to 100 meters, meaning that your cell phone is almost certain to be equipped with a GPS receiver. The police will therefore be able to locate you almost instantly, and the other car’s driver will be very grateful for that. Not only in such extreme cases is GPS on your phone useful, you can also get driving instructions on your phone by subscription, or by integrated software. The GPS function can also provide a simple map that shows you where you are and where you need to be going. Some applications even list near-by businesses just based on your location. This can be extremely convenient; imagine you just got out of a business meeting in a place in town you don’t know and are dying for a cup of coffee – you can just ask your phone for the location of the nearest Starbucks or coffee shop. Some phones can also be used to locate family members; or your car in case it is driven by one of your kids for example.

As you can see, GPS is a very effective new system for tracking, and the fact that it is available even on cell phones makes its use even simpler for the average person.