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The Global Positioning System.

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Introduction

The Global Positioning System Anna Reoch The global positioning system (GPS) is a satellite-based navigation system, consisting of a network of 24 orbiting satellites travelling on six different orbital paths. These satellites, referred to as NAVSTAR satellites, are constantly moving, making two complete orbits around earth per day. The first GPS satellite was launched in February, 1978. Satellites now weight approximately 1 tonne, and are about 5 metres across with extended solar panels. GPS needs at least 24 satellites to provide full coverage of every point on the earth, all the time. To calculate one position on the earth, at least 3 satellites are needed. Currently, there are 28 working GPS satellites, out of roughly 750 currently in miliary, civilian and commercial use. GPS satellites, quite simply, broadcast data - each satellite knows two things: its exact location in obit, and exactly what time it is. It knows its position within a few feet, whilst moving a t 17 000 miles per hour, and knows the time within approximately 100 picoseconds (1 trillion picoseconds to a second). The satellite signal also contains a 'psuedo-random code' - its identification, ephemeris and almanac data. ...read more.

Middle

A process known as Differential GPS (DGPS) employs a second receiver at a fixed location to compute corrections to the GPS satellite measurements. A number of free and subscription services provide these DGPS corrections, which will considerably improve accuracy. Without the use of DGPS however, accuracy has been measured with a global average error less than 13m. It was war that was the first to bring GPS to the popular imagination: initially in the Gulf War, and then this year, in Iraq. The US military uses its GPS to deliver bombs, missiles and even individual artillery shells to targes with complete exactitude. This is actually just an extension of the original intention of GPS - to provide guidance and position information to the military. Now however, the commercial and civilian uses of GPS have outstripped the miliary uses. In 10 years, GPS has proved itself an indispensable tool. It's predicted that at the end of 2003, as many GPS devices of all kinds will be produced as in the previous 25 years that the satellites have been in orbit, and that in 2004 the number of devices will double again. Indeed, GPS is proving itself a genuinely transformational technology. ...read more.

Conclusion

Anything of value, that has the potential to be stolen, could be relocated through GPS - everything will know its location, and be able to report it. Insurance companies would be able to sell auto insurance based on how you actually use your car. They then review the GPS information on where you've driven, how far, how fast, and can bill you for the risks that you're taking. A trial has already been performed in Texas using such a system. Indeed, commercial companies are now using GPS for ultimate knowledge - knowing exactly where their units are, and what they are doing, in the mould somewhat, of Big Brother. Big Brother-esque again, is the fitting of GPS chips into mobile phones. By the end of 2005, all mobile phones sold in the US must be able to report their location. The GPS phone will know where it is and be able to report that information, if it is stolen, in an emergency, if you are lost. Further GPS research can only further the dominance of this technology, providing a future with greater awareness, greater knowledge, openness and even wider communication, making the world once more a smaller place. ...read more.

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