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How Does A GPS System Work? |
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By Sebastian Marders
 A GPS, or Global Positioning System, is a navigation system which is satellite-based, and comprised of 24 satellites that the U.S. Defense Department placed into orbit. It was first intended for military functions and purposes. However, in the 1980s, the system was made available by the government for civilian service.
GPS works anywhere in the world, in whatever type of weather conditions, 24/7, making it very convenient to use. There are also no fees or charges for the setup and subscription to use it.
The 24 satellites of the GPS space segment navigation system are orbiting the earth at about 12,000 miles above us. They are continuously moving, and are traveling at the speed of roughly 7,000 miles an hour.
These satellites are powered by the sun. On board, they have extra batteries to serve as a backup and to keep them functional even in the event of a solar eclipse, when the satellites would not be able to extract solar energy from the sun. To keep these satellites flying along the right path, small rocket boosters are implemented.
The satellites used for GPS circle the earth in a very accurate orbit twice a day and broadcast signal information back to earth. The GPS receivers gather this information and utilize triangulation to compute and determine the user's definite location.
In actual fact, the GPS receivers evaluate the time a signal was put out by a satellite and compare it with the time it was acknowledged. It is the time difference that would indicate to the GPS receiver where the location of the satellite which transmitted the signal is and how far away it is. With measurements of distances from other satellites, the receiver can then establish the user's location and position.
A GPS receiver must receive at least three satellite's transmitted signals to be able to calculate and track movement, and establish the user's 2D position, that is, the longitude and latitude. The receiver can also determine the user's 3D position, which would include its altitude, latitude, and longitude, with four or more satellites in view.
Once the user's location has been determined, the GPS unit can compute other information. Examples of such information are track, distance to destination, trip distance, bearing, speed, sunrise time, sunset time and more.
These signals transmitted by the satellites are low power radio signals. They have been designated L1 and L2. These signals travel by line of sight, which means that they would not be able go through most solid objects such as buildings, but have the ability to pass through glass, clouds, and plastic.
A single signal contains three essential pieces of information - ephemeris data, a pseudorandom code, and almanac data. Ephemeris data tells the location-to-be of any GPS satellite during any time throughout the day. The pseudorandom code is basically an I.D. code. It is used to identify which satellite is the one broadcasting information back to the GPS receiver. The almanac data contains vital information about the satellite's status, either healthy or unhealthy, and the current time and date. This part of a signal is very important in calculating the location of a user.
Thanks to the parallel multi-channel design, GPS systems are incredibly accurate.
Sebastian Marders loves writing about a variety of things and sharing the website that inspires each piece with his readers. If you are interested in a GPS system on sale, including cheap Garmin GPS navigation, and TomTom GPS systems then please visit.
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