How Does GPS Operate?

Do you know how GPS works?  First, You need to know that GPS is an acronym for Global Positioning System. The Global Positioning System is a satellite-based positioning system developed and operated by the U.S. Department of Defense (DoD).

The global positioning system is comprised of three main components that enable the system to work as a high technology navigation system. People have used stars for navigation for thousands of years. Now GPS operates with satellites and microwave beams.

The Three Main Components of GPS

The primary components of the Global Positioning System include a network of NAVSTAR satellites, ground control stations and receivers.  There are 24 operational GPS satellites (plus 3 as reserves) currently orbiting the planet that each transmit a unique coded digital signal. The solar-powered, geostationary NAVSTAR satellites orbit twenty thousand kilometers above the Earth arranged to provide 24 hour global coverage. These satellites transmit a continuous stream of data.

Next, there are control stations and satellite upload facilities on the ground that are maintained by the U.S. Air Force. This includes one master control station, five monitoring stations, and ground antennas. The satellites are continuously tracked by the monitoring stations. Any changes in the satellites' positions are calculated and transmitted by the ground antennas to each satellite on a daily basis. This way each satellite is will transmit correct location data.

The third component of the Global Positioning System are the receivers that can be used by both civilians and military personnel.  The receiver functions as its name implies by receiving the satellite's signals.  There is no limit to the number of receivers that can use the GPS at any given time. 

Locate Your Position Using Satellites Twenty Thousand Kilometers Above

A user can locate his position by making a request through a receiver which uses a unique code sequence. Then, three or more satellite signals (four or more if elevation is requested) are acquired simultaneously to determine the distance between the satellites and the receiving unit. Using these distances, an accurate position is calculated by trilateration.

Each receiver is pre-programmed with the coordinates of the satellites. Depending on the type of receiver, the reported position may be accurate to within ten to twenty meters. Differential GPS (DGPS) receivers which compare there calculated position to a known location are much more accurate than other hand-held GPS units. Differential and stationary GPS receivers can be accurate to within one meter. 

How the Global Positioning System works is a wonder of our technological age. It is an amazing achievement that these GPS receivers can communicate simultaneously with satellites in geosynchronous orbit twenty thousand kilometers above the Earth and give us an almost instantaneous answer to where we are at any given moment.