New GPS Standard Published

jeffy124 writes: "The Dept of Defense has released a new standard for GPS. The new standard will go into become available for use starting in 2003 when the first satellites are launched. Full completion is estimated to 2014. The new standard allows for greater horizontal accuracy of 36 meters instead of 100 meters, and also sets a new baseline for transmission protocols that circumvent ionic interference."

Current GPS can do better than that...

[Cerlyn]

A civilian differential GPS reciever always was able to do better than what selective availabilty should have allowed. These units gave (and still give) accuracies within 15 meters or so. Given a Loran compensation reciever (used to pick up posititioning signals meant for boats), one can improve on this accuracy by using additional known transmitters located at ground-based reference points.

If you want "new" GPS units that were recently releaesd in the past year or so, look for units with the Wide Area Augmentation System (WAAS). Implemented alongside with the FAA, these units rely on two additional satilite signals for an average accuracy of three meters.

Obligatory manufactuers links: Garmin's GPS description page [garmin.com] and Magellan [magellangps.com], another GPS supplier.

hate to break it to you but...

[Anonymous Coward]

this is nothing new at all. You're being a bit vague when you say it's a "new standard." Think of it more like a report on the current state of GPS for civil users; the DoD is simply saying that their old estimates of average performance were off and they're correcting themselves. The numbers in that report only reflect what can be done right now with GPS (in terms of a stand-alone receiver, no differential GPS).

The next real improvement in GPS accuracy will come with the launching of the next few blocks of satellites (IIR, IIF, III). The Block III satellites aren't slated to be deployed until at least 2010 [gpsworld.com] and will include the new M code for more accuracy. Even sooner, the Block IIF satellites will support the new L5 channel for civil users which will give the public sector a big improvement in their accuracy. The C/A code (for public users) will be turned on L2 in the release of the IIR satellites starting in a couple of years. Up to now, the L2 channel was only for P(Y) code which public GPS users didn't have access to (P(Y) is the military PPS code (precise positioning service) and is heavily encrypted). And more improvements will be made as the OCS (operational control segment - the Air Force group that monitors and controls the GPS constellation) that will make GPS even more accurate and reliable.

But don't expect any more significant improvements in GPS accuracy until these new blocks of satellites are launched. Of course, these improvements exclude things like WAAS and other differential GPS solutions which will give a much more precise position solution than any single receiver can accomplish.

Here's a good page [navy.mil] describing some basic GPS terms I used. Also, for a good summary of the lastest GPS modernization efforts, read this article [gpsworld.com].

t.

Re:Furthermore this won't change non military use

[nathanm]

Despite these artificial limitation posed by the the US and Australian DoD, apparently everyone who's wanted to has been able to get accuracy to within fifteen meters for quite some time now.

It's not an "artificial" limitation. When they say GPS has a 36 m accuracy, they mean there is a 95% Circular Error of Probability (CEP) that it will locate your horizontal position on the Earth's surface any day within a 36 m sphere. It's quite possible that the position is more accurate. Some days, the accuracy with a 95% CEP has been as low as 7.8 m, and the 50% CEP as low as 2.9 m (both with only single frequency receivers).

Do the sattellites give bad readings which can be easily re-set to their true value, is some kind of interpretarion of multiple results possible (a kind of triangulation)? Either way, this has been the case for over five years.

Before May 1, 2000 "Selective Availibility" introduced a timing error that limited the 95% CEP accuracy to 100 m for civilian receivers. It's been turned off for good now, but the DOD has reserved the right to degrade the signal in a specific region, probably by jamming it.