"GPS is a humanitarian weapon system" says Dr Bradford W Parkinson, Chief Architect of Global Positioning System http://mycoordinates.org/his-coordinates-2/ "Just before the first Iraq war, the US had turned on the GPS Selective Availability feature. But the irony was that, as soon as the war started, they decided to turn it off since many of the soldiers had civilian GPS sets. It was hurting themselves. We never should have done it in the first place." "Incidentally, I was very instrumental in getting that turned off; my argument always was that wiggling the signal with selective availability was only going to speed up the introduction of differential systems and that is exactly what happened. By 1978 we had already demonstrated differential GPS that could reduce errors to about 2 meters, so I said why on earth would you try and put something in place that is so trivially defeated." ------------------------------