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The Doppler Effect gave scientist the idea that satellites in space could be tracked from Earth by measuring the frequency of radio signals.
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It was built by the Navy to locate submarines.
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The Aerospace Corporation figured out that if you send signals continuously, moving vehicles and aircraft could be tracked.
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The branches of the military launch the first of twenty-four satellites into space which they refer to as NAVSTAR.
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The military launched 11 more satellites that carried atomic clocks to measure times more accurately.
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Used in commercial aircraft to increase safety and navigation.
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They launched it into space using a Delta II rocket.
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Magellan Corporation is the first to market hand-held navigation device.
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The first GPS system was completed when the last satellite was launched in 1995. The satellites circled the globe two times per day.
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Mobile phone manufacturer Benefon launched the first commercially-available GPS phone that was sold mainly in Europe.
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Private companies began producing personal GPS products.
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Cellular signal and GPS signal to locate the user to within feet of their destination. This is the way we think of GPS now.
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The two new satellites enhanced the existing GPS and allows the GPS to stay in operation in the next generation.
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At least 24 GPS satellites are operating at all times with three deactivated satellites that can be reactivated if necessary.