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... Leaving a trial of stones, marking trees and referencing mountains are examples of primitive navigational aids. ... The receiver when turned on measures the distance from the transmitter as 1000m. ...
GPS (Global Positioning System)
Left the Stones and now into Satellites
GPS is similar to star based navigation. ... GPS is composed of 24 satellites in 6 different planes located 11,000 miles above the earth that act as fixed reference points. By measuring the travel time of a signal transmitted from a satellites, a receiver can calculate its distance from that satellite. When receiving the signals from at least 4 satellites, a receiver can determine latitude, longitude, altitude, and time.
There are five master ground stations located at Hawaii, Ascension Island, Diego Garcia, Kwajalein, and Colorado Springs that continually track and correct the satellites for variations in position and time and errors. ... These panels capture energy from the sun which provides power for the satellite throughout its life. ... The signals generated by the radio transmitter are sent to GPS receivers via the L-band antennas. Each of the 24 satellites transmits its own unique code in the signal. Since GPS was developed by the Department of National Defense, each satellite emits two separate signals, one for military purposes and one for civilian use. ... Than standing at the receiver, you would hear two versions out of sync, one from the receiver and one from the satellite (delayed). If you wanted to see just how delayed the satellites version was, you could start delaying the receivers version until they fell into perfect sync. That delay time is equal to the travel time of the satellites version. ...
Picture from http://www. ...
How to make the clock in the receiver an Atomic Clock (Clock Bias)
Getting the time exactly right is very important in GPS. ... To solve for this error a 4th satellite is used to coordinate time by comparing the travel time in 3 satellites to the travel time of the 4th satellite. ...
Adjusting for clock bias is how GPS can not only tell you right where you are, but also exactly what time it is.
Approximate Word count = 1702
Approximate Pages = 6.8
(250 words per page double spaced)
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