The Global Positioning System (GPS) was originally developed by U.S. military satellites were launched (the first satellite was launched in 1978) is moving towards employment. The system consists of a network of 24 to 32 satellites orbiting at about 7,000 mph, in a way, twice a day.

In the early days, the soldiers could not trace the signal, but in the 1980s, was opened to the public.

Before going into details, it is important to recognize that the use of the satellite network is free, no subscription required.

Another advantage is that the system is essentially independent of the weather and it is everywhere in the world. Some recall the Loran system, which was popular with circular saws, before GPS popular.

Loran has a very precise, but only in limited areas where transmission of signals of May and if sufficient time was not harmful.

GPS satellites orbiting the earth, the transfer of a very precise and consistent. As they orbit about 12,000 miles sparks 24 hours a day, every day. The receivers we use only receives broadcast signals and the time to compare the signal against time is sent. Knowledge of the signal travels at a fixed rate of speed, it is easy to calculate how far away the satellite and the receiver of the other.

If this process were done with only one satellite, the result would be useful for us because this is the only possible explanation of the situation. To ensure the accuracy of the receiver has received signals from at least 3 satellites.

In practice, receivers under typical signals from several satellites.
To enter data such as speed, direction, distance, etc. of the receiver repeats the calculation of the position on a continuous basis and therefore an update of the position and other data. The signal is transmitted by the satellite ID, the satellite position at a certain time and date and time.

Accuracy of receiver is improved with advances in technology to an average of about 15 meters. In practice, general practice, see the precision of one to two meters, at least temporarily.

When the GPS was opened to the public, the signal was intentionally degraded by the government, which is known as Selective Availability (SA). SA has been established so that citizens have a total accuracy of the system.

Technology as the Wide Area Augmentation System (WAAS) improves available with a number of beneficiaries on the accuracy of about 5 meters. Reception technology are equipped with a differential corrections to the information based on other known references.

The end result is the functionality and accuracy of GPS receivers so that we can all trust. Accordingly, we now see and enjoy GPS watches, boats and navigation systems GPS car GPS integrated.