history - History of the GPS system 1964 Navy Navigation...

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1 History of the GPS system 1964 – Navy Navigation Satellite System (NNSS), also called Transit, becomes operational Provide 2 dimensional fix using the Doppler shift of the signal ~5 satellites in low (800 km) polar orbit Primary purpose to help submarines navigate 1967 – first Timation satellite launched Precise time and time transfer Side tone ranging 1973 – Joint Program Office (JPO) formed 1978 – first operational prototype satellite launched 1988 – 10 satellites operational 1989 – first block II satellite launched 1994 – full constellation; 24 satellites
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2 GPS System Segments
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3 GPS satellites 21 23 28 3 15 31 17 26 5 9 19 12 27 7 2 16 • 24 satellites • 6 orbital planes • 55 degrees inclination • ~26,500 km radius Overview
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4 GPS Block II Satellite 820 kg three axis stabilized two Sun sensors, Earth sensor, & three gyros for attitude determination 22 thrusters and four reaction wheels for attitude control Solar panels, 7.2 m 2 , 800 watts 5 feet wide, 17.5 feet long (length includes solar panels) 12-helix-element phased array antenna
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5 GPS satellites Block I Proof of concept Block II Automatic error detection No autonomous momentum control Will tumble 28-45 days after last ground contact Block IIA Autonomous onboard momentum control Can function 6 months without ground control URE bounded by 10,000 meters after 180 days Block IIR AutoNav turned on or off by ground control AutoNav: maintain own ephemeris & clock for 180 days by ranging to other satellites URE bounded by 7.4 meters after 180 days
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6 GPS satellite status
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This note was uploaded on 01/15/2012 for the course EEL 6935 taught by Professor Staff during the Fall '08 term at University of Florida.

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history - History of the GPS system 1964 Navy Navigation...

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