HOW DOES GPS WORK?

GPS or Global Positioning System is a constellation of 24 satellites (5 satellites plus a spare). The 24 satellites that orbit the earth at a distance of 20,200 km 2 times a day, with news broadcasting radio waves. U.S. Defense Department operates the GPS system has been set up satellite configuration such that all places on earth can receive signals from 4 to 10 satellites. As a timepiece, each satellite equipped with 4 atomic clocks that measure time with precision one-millionth seconds. GPS technology could determine any location on earth with an error less than 1 meter.

To take advantage of GPS, we must use the GPS receiver (GPS receiver). This tool will show you the location coordinates in the format, as usual on the map. If you notice, every map is always equipped with transverse lines and longitudinal. Based on the coordinates of latitude and longitude that we determine the position of a place. Well, GPS also has the same coordinates called Waypoint. Of course, the GPS Waypoint more thorough and more accurate than map coordinates.

How GPS receiver can display the coordinates we? The method used is very simple. If the GPS receiver in hand, we know the distance between our locations and 3 GPS satellites, and has information about the position of these satellites, the location we can easily be calculated. To be more clear, consider the following story.
Tommy wants to come to a birthday party of Michelle in the Building G. Unfortunately, Tommy does not know where that building. He only had information that the Building G is located 10 km from the University of X, 15 km from Market Y and 20 km from Terminal Z. Since Tommy has a brilliant ideas, He draws three circles centered at the University of X, Y and Terminal Market Z, each with a radius of 10, 15 and 20 km. At the third intersection point of the circle that is located Building G.

The way in which Tommy used is called three-literate method. The same principle is used in GPS. The difference, the GPS receiver will not draw a circle, but only with a row of numbers to calculate mathematical equations.
How does the GPS satellite positioning and knowing the distance? Satellite position easily known because each satellite will notify the coordinates through a special signal. The receiver can easily identify from where a satellite signal comes, and then match the satellite positioning table is always updated from time to time.
Distance satellite and the receiver is calculated with a clever way. At certain times, the GPS satellites transmit a digital code. At the same time, the receiver runs the same code. Having to travel far enough, the code from the satellite will be delayed compared to the code that runs the receiver. Time delay is considered as a signal travel time. Next easy. Distance equal to the time interval times the speed. By multiplying the signal travel time and speed of propagation of the signal (equal to the speed of light), the GPS receiver can know the distance to the satellite.
After knowing the distance between a receiver to each satellite, the receiver computer to start counting. To determine the 2-dimensional position (latitude and longitude), the GPS receiver to detect signals at least 3 pieces of the satellite. 3-dimensional coordinates that include altitude locations can be determined if the receiver got the signal from the satellite 4 pieces or more.