GPS What is GPS? GPS consists of three components:-
The signals from the satellites say very accurately where the satellite is, and what time it is. How does it work? Knowing that the signals travel at the speed of light, the time differences allow the receiver to work out how much closer it is to each satellite compared to the others. With some clever mathematics, and the information of where the satellites are, the receiver's position in 3 dimensions is calculated. The time and the speed the receiver is travelling at are also worked out. Incorrect explanations A predecessor of GPS, the DECCA system was a two dimensional version, with ground-based transmitters. The earliest DECCA systems only worked out the time differences, and left the user to work out the position. The charts to help with that had curves overlaid, called hyperbolae, which were lines of all the points a certain distance further from one DECCA transmitter than another. The principal is the same as GPS, in that difference in distance from the transmitters is what is measured. If it was distance from each transmitter that could be measured, the DECCA charts would have had circles not hyperbolae drawn on them. |
819516344 positions tracked
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