Measure the intrinsic importance of GPS to both national and global infrastructures by this gauge: after a year or more of careful planning, it will take a further 12 years to wean a community of more than 300,000 professional, industrial users from a technology that was never intended in the first place. Not designed-in, nor ever officially announced, sanctioned, or promulgated.
That’s the state of affairs for real-time kinematic GPS, dual-frequency as we know it today, semi-codeless or carrier-phase use of the highly precise military P(Y) code on L1 and L2.
Jason Kim of the National PNT Coordinating Office used this analogy to describe it: “Think about a person who owned a piece of land and who planted an apple tree in the corner of his lot for personal use. As seasons went by, some apples fell to the ground, and he wouldn’t use those, he’d just harvest the ones on the tree, but the kids in the neighborhood would come along and pick up the apples. They asked for permission, and he said no problem, it doesn’t hurt me to allow people to pick up these apples that have already fallen, as long as they’re not picking the ones off the tree. Years go by, more and more people start coming by, and soon they’re selling the apples that fell on the ground at little roadside stands and making a living off this apple tree — which was never really intended in the first place. Then if the owner wants to make any modifications to that land where the tree stands, people are going to get upset. So all of a sudden you have almost a requirement to maintain the tree, which reduces the owner’s flexibility, just to keep these people happy who are picking up apples off the ground.
“To take this further, we’ve planted two or three more trees in another part of the land, and we’re saying, we want to help you guys because we realize that this is very important to you, so we’re dedicating trees for you to exploit in the future. We’re giving you notice that we want to you to stop using the first tree, because we’re going to use that piece of land for something else. Maybe we’re going to build a shed or who knows what, doesn’t really matter, but we own this land so we’re going to be taking back that part of it. We’ve already built all this other stuff for you.”
Just offhand, I can’t think of another industry or community in which this scenario might play out. First of all, that such a widespread and ingrained practice, essential here to surveying, construction, aviation, agriculture, and all high-accuracy augmentation systems, would develop simply from civil engineering ingenuity and adaptability.
Second, that an arm of government would take such elaborate care to nurture it, “bending over backwards until we have at least two other civil signals,” as Air Force Col. Mark Crews puts it.
Is GPS a great community or what?
