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The first GPS: Global Positioning System

The first form of conventional portable GPS (Global Positioning System) was originally put up by the United States, initially as a military navigation system. However, it soon proved so useful for civilian purposes that it became "The GPS", and had widespread use globally. It had many things going for it, but had an unfortunate built-in error in the location, which it has been speculated was put in so that enemies of the USA would not be able to use the US-made GPS against its forces!

The term "GPS" of often used for referring to any Global Positioning System, but also specifically to the first system which was put into orbit. The term "GPS" has been routinely bandied-about to mean both things, making it difficult to refer to the later Galileo GPS without confusion.

The idea of introducing the error in the early US Military GPS was supposed to be enough to make missiles go a bit off-course. However, this didn't work. Even though the error signal was different every day, so people were inconvenienced on their way to work, it was not very effective against perceived enemies. Quite simply, any fixed structure with a GPS in it could average out the errors and find its real location, and then with each new day and new error signal, it could broadcast the correction factor to anyone within range who wanted to get an accurate position. This was "Differential GPS".

Because of the error signal, and because the whole GPS setup was switched off every now and then, and possibly for other reasons, the United States GPS became such that many countries did not trust US GPS! Countries in Europe also required a higher accuracy system, as well as being a system that wasn't controlled by the USA. Some countries, it is suspected, had a good degree of scepticism in the reliance on a United States system for other reasons. So, a European version of Global Positioning System, known as Galileo, is being put up. This was much more accurate, and did not have any built-in errors. Initially the United States didn't take much notice of the European system, but before the first of the satellites got into orbit, the United States threatened to shoot down the European system if it didn't comply with the US being able to jam it, or at least that's the rumour I heard. So, beware! The European Galileo GPS is still not Pure GPS, and could be cut off at any time to any region of the world, at the whim of political powers that think there's a reason, in other words, for almost no reason at all.