Slashdot Mirror

Actually WAAS isn't what Clinton 'turned off'. He turned off selective availability or SA. SA basically injects false information into GPS timing you get a less accurate position.

more info here

In a joint statement yesterday, http://www.igeb.gov/2004-US-Russia-statement.pdf, the United States and Russian Federation announced "their commitment...to continue to provide the GPS and GLONASS civil signals appropriate for commercial, scientific and safety of life use on a continuous, worldwide basis, free of direct user fees."

Sounds as though they want to quench any arguement Europe may have in regards to the reinstatement of Selective Availability (although we must remember that SA was not reactivated even after/during the September 11th attacks). Not like this will make any difference though.. the EU has its heart set on implementing its own satellite navigation system - I for one will welcome the increased accuracy this will bring, especially in tight city streets where it is currently hard/impossible to get a good satellite lock("shooting the bird"). OTOH, at least it isn't American taxpayers footing the bill this time! :) Redundancy is good in any system.

I wonder when receivers will be on the market which lock onto GPS & Galileo? Perhaps firmware upgrades could suffice on newer models?

The correct links for the US-administered GPS satellite constellation, known as NAVSTAR:

NAVSTAR GPS Joint Program Office - responsible for operational maintenance of NAVSTAR GPS equipment, services, and infrastructure

Interagency GPS Executive Board - executive management of NAVSTAR GPS

GPS fact sheet - US Air Force facts about NAVSTAR GPS

US Naval Observatory NAVSTAR GPS home page

Further information:

FAS GPS background info

Global Security GPS background info

The official sites to monitor if you're worried:

www.igeb.gov: The IGEB is a senior-level policy making body chaired jointly by the Departments of Defense and Transportation. Its membership includes the Departments of State, Commerce, Interior, Agriculture, and Justice, as well as NASA and the Joint Chiefs of Staff.

Right after 9/11/01, they posted (still there) this: "GPS Selective Availability (SA) has not been used since its deactivation by the President on May 1, 2000. At that time, the United States Government stated that it has no intent to ever use SA again. There has been no change in this policy."

http://www.navcen.uscg.gov/gps/default.htm is the official source for notices to civilian GPS users about schedule satellite outages, etc. They have nothing related to S/A being turned back on, and they certainly would if it were going to happen.

We can jam or dither the civilian code over the theater if we need to.

The Interagency GPS Executive Board (IGEB) was established in 1996 by a Presidential directive to manage the Global Positioning System (GPS) and its U.S. Government augmentations. The IGEB is a senior-level policy making body co-chaired by the Department of Defense and the Department of Transportation.

The IGEB have a statement on their website about Selective Availability.

GPS Selective Availability (SA) has not been used since its deactivation by the President on May 1, 2000. At that time, the United States Government stated that it has no intent to ever use SA again. There has been no change in this policy.

Of course they could change this policy, but for the moment it looks like SA will not be turned on.

From the FAQ

With SA gone, do I still need differential GPS (DGPS)?
It depends on your specific user requirements. If you are using GPS for safety-critical navigation, you will still need to use the Coast Guard DGPS or Nationwide DGPS to get the higher accuracy (1-3 meter) and the integrity monitoring/warning service. If you are a surveyor requiring sub-meter positioning, you will still need some form of DGPS to achieve that level of precision. On the other hand, if you are a trucking company using GPS to track and manage assets, the

1. Civilian: this is what anyone can access. This was discontinued because companies were about to come out with units that compensated for the programmatic imperfections the satellites were feeding the receivers. It was accurate to within one hundred meters, and is still applied on a regional basis (for instance, Iraq still has Civilian-level GPS accuracy).
2. Military: this is now what both civilians and the general military share. It is accurate to within approximately twenty meters.
3. SpecOps: this is what the SEALs, DEVGRU and all their friends use. It is accurate to within approximately one meter.

The URL in the announcement was a moving-target pointer to the White House Press Releases,
so today's 0th press release is something about www.americasteens.gov, a Federal program to prevent the corruption of our kids' precious bodily fluids or something. If you dredge the pointers to previous days, you get a probably-moving-target pointer
http://www.whitehouse.gov/library/PressReleases. cgi?date=2&briefing=5 , which at least tonight points to the real site
www.igeb.gov

...consider a football stadium. With SA activated, you really only know if you are on the field or in the stands at that football stadium; with SA switched off, you know which yard marker you are standing on.
-Dr. Dennis G. Milbert
Chief Geodesist

...consider a football stadium. With SA activated, you really only know if you are on the field or in the stands at that football stadium; with SA switched off, you know which yard marker you are standing on.
-Dr. Dennis G. Milbert
Chief Geodesist