Before the arrival of the General Positioning System (GPS) technology, having a trip was certainly the most daunting experience in our life. For instance, it was perfectly acceptable to see a situation where someone was driving his car, another one was looking at the map to find the right direction, quite funny! Nowadays, this situation is obsolete and ridiculous for GPS systems have drastically changed the way we used to deal with route finding during a trip. Indeed by just installing a GPS device in your car, you can accurately and safely get the right direction.

Usually when someone mentions GPS, he is referring to the GPS receiver even if the GPS architecture is actually more complex than this small device installed in your car. In short, GPS systems are a cohort of 27 satellites rolling around the center of the Earth. Only 24 satellites are fully functional while the remaining ones are just used for storage purposes. The military industry pioneered the technology before being used for general purpose by the public.

Each GPS satellite powered by the Sun rotates around the center of the Earth completes a distance of about 12,000 miles which is equal to 19,300 kilometers. The actual trajectories of these satellites are made so that at least four satellites are available in the space at any time. The GPS receiver is responsible of finding these available satellites, working out its distance to these satellites and finding its position. This process makes use of a mathematical model called trilateration.

The GPS signals are hindered by weather conditions. Nowadays, there are many research projects aiming at finding ways around this issue in order to increase the correctness of GPS systems. Having located the satellites, the triliteration is used to work out its distance and reduce these errors.

Briefly speaking, GPS systems are used for several purposes mainly as guiding aid. The user simply needs to input his final destination and the GPS receiver will do the rest of the job. GPS systems can also be used for tracking purposed as it is noticed in the automobile industry.

The GPS technology is also used for many other purposes. For instance, in the automobile industry, GPS systems are used to deter car thieves. Private investigators are also making use of the GPS technology in order to monitor a cheating wife. The GPS technology is also extensively used in the military industry as it was pioneered by the army. Some military usages include navigation, target tracking, missile and weapon guidance, search and rescue lost soldiers and acknowledgement and map creation. The possibility to keep track of a vehicle position every time is an appealing feature of the GPS technology. Other systems can furthermore keep track of a driver. This feature is of great help to anxious parents who are concerned about their children's ability to safely drive.

Another use of the GPS for civilian purpose is to help prevent civilian GPS guidance from being used in an enemy's military or improvised weaponry, the US Government controls the export of civilian receivers. A US-based manufacturer cannot generally export a GPS receiver unless the receiver contains limits restricting it from functioning when it is simultaneously at an altitude above 18 kilometers and traveling at over 515 m/s.