Slashdot Mirror

← Back to Stories (view on slashdot.org)

U.S. May Reduce Non-Military GPS Accuracy

Posted by timothy on from the geocaching-will-be-more-challenging dept.

ward99 writes "The U.S. government may be degrading GPS satellite signals, to cripple Iraqi forces' ability to use those systems during the war. This could potentially reduce accuracy from ~3 meters to over ~100 meters. Users depending on GPS systems may want to do sanity checks on any data returned by those systems during the war. The U.S. will do this by increasing the inaccuracies on the civilian C/A code, turning back on S/A (Selective Availability), by having the satellites deliberately and randomly return inaccurate information on where they are. S/A degrades GPS accuracy to only 100 meters 95 percent of the time and 300 meters the other 5 percent of the time. This will not effect the military P code."

4 of 654 comments (clear)

  1. There is no evidence of the claim by MyNameIsFred · · Score: 5, Insightful

    Let me understand this, the head of a German Autoclub says the U.S. military MAY, I repeat MAY, degrade GPS accuracy. No evidence. Just pure conjecture. Consider that GPS has woven itself into our lives. How, it arguably supports critical functions. I strongly doubt that they will do this. While I understand the world's fears concerning GPS because it is run by the military, I put this article in with all FUD.

  2. Alternatives by Bozovision · · Score: 5, Insightful
    And this is EXACTLY why the EU wants their own alternative civilian version of GPS, and why the US has argued against it. Suprise!

    Apparently the Pentagon sees no compelling reason for an alternative to GPS. Oops, that would be before they checked their GPS units round about now. Oh wait, I forgot, they have their fingers on the buttons, perhaps that why they can't see a compelling reason.

    Oops look; those pesky photons might interfere with each other

    On the other hand, to be fair, the US could have just degraded the signal without announcing it. At least now ships and planes probably won't be piloted into rocks.

  3. Re:Army's stuff by EzInKy · · Score: 5, Insightful

    Army doesn't own it. People own it. The money spent on the satellites came from people's taxes.

    And the people (through their elected representives) gave the money to the Army for military use.

    --
    Time is what keeps everything from happening all at once.
  4. Checking the official resources... by jvaigl · · Score: 5, Insightful
    It's an interesting discussion, but doesn't look like it's going to happen. The article they're referring to is just some German auto club that says the thing maybe it could happen when the war starts. Hardly authoritative.

    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.