How GPS Tracking Systems Work
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The Skinny on GPS
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We can thank the military for the Global Positioning System (GPS). It was originally used in the Gulf War to aid troops in navigating the desert. Then in 2000, it became a service available for the public's benefit.
Navigation with the Aid of Space
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GPS is a system of navigation that depends on satellites for its information. The military bears the brunt of the expensive technology as it costs millions of dollars to keep up with the more than two dozen satellites circling around Earth.
For someone to access GPS tools they need a receiver---but they also need to be in an area that can receive signals, as it cannot always be read through walls. Signals can also be compromised by high buildings or trees and foliage interference.
In order for a location to be calculated, transmission information from at least three satellites needs to be tapped into. This process is called "trilateration." The GPS receiver needs to recognize the location of the satellites involved, plus the distance between the receiver and the satellites.
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How Fast is Fast?
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These variables are determined by identifying high frequency, low-power radio wavelength signals. Radio waves are forms of electromagnetic energy. This type of wave power frequency travels at about 186,000 miles per second, or at the speed of light. The GPS receiver is analyzing the journey between the satellite and itself.
Atomic Clock Accuracy
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An involved process, the satellite must be time-synced to an atomic clock. As the satellite transmits its "pseudo random code"---a digital pattern---the GPS receiver calculates the length of the signal's travel time, against the delay of reception. This information also factors in the satellite's orbits, their clock corrections and other system positioning.
Of course the receiver cannot possibly support an atomic clock because the costs would be prohibitive, but it does use a quartz clock that can constantly reset itself. All of this technology is a complicated procedure that we can break down to its simplest by saying the receiver is gathering and calculating a time value using the incoming signals broadcast from space that align with the satellite's atomic clocks that all intersect to a single point in space.
Thank the Department of Defense
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The receiver is programmed with a type of almanac that relays where every satellite should be at any given time. Changes in the pull of planets can alter satellite orbits, but it is all monitored by the Department of Defense who makes the necessary adjustments and corrections.
Gaining in Popularity of Usage
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The technology today is often found in cars but has been adapted to track pets, in wildlife research, law enforcement tailing and recovery of stolen vehicles, and can provide a "geofence" around expensive construction equipment or company assets, as a kind of theft prevention element.
Another popular application is for recreational use in helping hikers, skiers and other adventurers find their way. GPS technology has been used successfully in finding stranded and lost outdoor enthusiasts who get waylaid by the elements or even buried under snow.
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