The satellite arrangement is such so constantly a minimum four satellites are focused on earth.
The primary function of car GPS systems is to give driving directions.
GPS is useful tool for map-making, land surveying and tracking.
From night star reading to ground track studying, then to the compass and now to the GPS, definitely the methods for directions and for not getting lost have been improved significantly. Nowadays it is possible to go into the nearest shop with electronic accessories and get a little thing that can tell us at anytime our exact position on planet earth. If you would like to know how a GPS receiver can do that, then go through this article.
The letters GPS stand for Global Positioning System and basically it is an arrangement of 27 earth-tracking satellites. These satellites move constantly around the earth (at about 12,000 miles) completing two turning rounds each day. The satellite arrangement is such so constantly a minimum four satellites are focused on earth.
A GPS by identifying the position of four or more of those satellites and understanding the distance to each one, then analyses that information and figures out its own position. This analysis comes out from a not so complicated mathematical theory called trilateration.
Every GPS satellite sends data that show where they are located at that moment. This is done simultaneously by all the satellites with their transmitted signal being received by the GPS receiver more or less the same time, depending on the location of each satellite. To determine how far the satellites, the time for the signal to be received is estimated. The GPS device then calculate how far it is form no less than four GPS satellites it can calculate its position in three dimensions.
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Although three dimensional and two dimensional trilateration appears not to be an easy mathematical principle, even if mathematicians argue with that, what is important is that finding a location nowadays could not be easier. And more importantly thanks to the assistance of such tracking systems many people’s lives have been saved.
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