It's finally happened......
It’s finally happened. As if the advent of GPS itself wasn’t enough to fundamentally change the whole business of cruising, providing cheap, accurate position-fixing for even the most inept navigator, now the US Department of Defense has gone the whole hog: Selective Availability is no more.
It’s true. A system that used to give us 100m accuracy, and often better, is now ten times as good. Freely available in its unadulterated form, with no built-in errors to downgrade the military-standard signals for civilian use, standard off-the-shelf GPS is now good for accuracy of 10m or less.
Cynics like our navigation correspondent (we’ve got the full story in Bartlett on Naviagtion this month) will say that it’s because there’s an election coming up in the US, and both the automotive and mobile phone industries have been leaning hard on the US government: after all, 100m accuracy isn’t a lot of use if you’re navigating in downtown Manhattan. And they may well be right – but whatever the reason, the bottom line is that those GPS satellites no longer discriminate between cruisers and cruise missiles, and that is an extraordinary idea to conjure with.
If you’re one of those who spent the extra money on a differential receiver, don’t be too glum about it. The differential base stations still serve a purpose. The only errors available for them to iron out now are the rather arcane ones that occur naturally, but it still means a tenfold improvement. That’s right, 1m accuracy instead of 10m: or different, yet correct, position readings for the chart plotter at the navigator’s station and the GPS receiver at the helm.
And what possible difference is it going to make to us all? Well – none, obviously. But hats off to the US taxpayer all the same: this one’s on us.
