Global Positioning Systems - How They Work

The Global Positioning system (Gps) was originally developed by the Us soldiery who launched satellites (the first satellite was launched in 1978) into orbit. The system consists of a network of between 24 and 32 satellites orbiting the earth at about 7000 mph, in a accurate manner, two times every day. In the early days only the soldiery could track the signals but in the 1980's it was opened up to the normal public. Before we get into the specifics it is foremost to comprehend that the use of the satellite network is free, there is no subscription required.

The other advantage is the system is essentially unaffected by weather and it is accurate in any place in the world. Some might recall the Loran system which was favorite with boaters before Gps became popular. Loran was capable of providing a very accurate position but only in slight areas where the transmission of signals was adequate and in case,granted the weather was not adverse. Gps transmission satellites orbit the earth in a very accurate and constant manner. As they orbit 12,000 miles above, they transmit radio signals 24 hours a day, every day. The receivers we use simply receive the transmitted signals and assess the time the signal was transmitted against the time it was received. Knowing the signals tour at a fixed rate of speed makes it easy to intuit how far the satellite and the receiver are from each other.

Gps Boating

If this process were done with only one satellite the consequent would not be useful for us since it would only indicate a inherent arc of a position. To supply accuracy the receiver has to receive signals from a minimum of 3 satellites. In actual use, the receivers typically track the signals from many more satellites. In order to supply data like speed, direction, length traveled, etc. The receiver repeats the position calculation on a continual basis and thus updates the position and other data. The signal transmitted includes the satellites Id, the satellites position at any given time and the date and time. Accuracy of the receivers has improved with technology advances to an median of about 15 meters. In real custom it is base to see accuracy within a meter or two, at least at times.

Global Positioning Systems - How They Work

When Gps was opened up for social use the signal was intentionally degraded by the Government which was referred to as Selective Availability (Sa). Sa has been discontinued so civilians now enjoy full accuracy of the system. Technology referred to as Wide Area Augmentation system (Waas) ready with some receivers improves accuracy to about 5 meters. Receivers qualified with Differential technology apply corrections to the data based on other known references. The end consequent is accuracy and functionality of Gps receivers to the point we all can rely upon. As a consequent we now see and enjoy Gps watches, auto and boat Gps navigation systems, Gps cell phones.

Global Positioning Systems - How They Work

Relate Gps Boating Relate Video

On Target with GPS Video Clips. Duration : 9.33 Mins.

Learn more about GPS and how it works in this video produced by NASA and Air Force Space Command.

Tags: GPS, Air Force Space Command, AFSPC, NASA