Slashdot Mirror
U.S. May Reduce Non-Military GPS Accuracy
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."
Don't like it, but it's the army's stuff. They can degrade it that far if they want to. Don't like it? Send up your own GPS satalites.
Mod point free since 2001
Do they really know how much a captain depends on GPS these days, especially when it comes to passing in and out of harbors? I hope this won't wreck another tanker somewhere.
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.
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.
S/A has always been a bit of a farce. It can be circumnavigated (no pun intended) if you use Differential GPS.
Basically, you set one GPS receiver up at a known, surveyed location and program that location into the unit. Then when the receiver trilaterates its position based on the information the satellites provide, it does on-the-fly corrections (You say i'm here, but i know i'm here). It can then use that correction algorithm to correct the positions of other receivers.
Of course doing that part on-the-fly is a bit more difficult (read expensive) because now you have to invest in radio communications back and forth between the two or more receivers - but it's often done. There are even services that have base stations set up across the country that sell a subscription-based service for that purpose.
Most times, survey firms just log the data and correct after-the-fact back in the office from the base station (the differentiator) located in the same area.
All in all, S/A only imposes the error to systems that don't have the capability == money to do DGPS.
There are 01 types of people in this world. Those that understand binary, and me.
I guess we all just pospone that trip to the wilderness to get away from things..
Take a MAP ( remember those things? ) on your next road trip...
After the war the service will return to normal.
Besides, who said we had a right to use GPS anyway?
---- Booth was a patriot ----
GPS is much more important to the US military, which does not have on-the-ground knowledge there. The US should be more worried about the Iraqis jamming GPS signals and other communications.
Of course, so far, it looks like Iraq is pretty feeble militarily. I suspect the war will be over very quickly. Which brings up the question again: why are we going?
In the USian Army we required 100m accuracy for Armor, 10m accuracy for Infantry/dismounted folks. All of the instruction had these tolerances.
...).
Yes, but did you need these tolerences ? For infantry navigation, you usually don't (Except for some extremely bad terrain types, an infantry officer/noncom who loses himself in an 100mX100m sized square won't do any good anyhow
For precise indirect fire, you do, but then again, my guess is that the Iraqi artillery (both light and heavy) positions are already very well measured.
The US army doctrine probably requires these accuracies simply because they can get it relatively cheaply. Nothing wrong with that; in fact that's the correct thing to do. But that does not mean an army can't fight well with less accurate equipment.
Working for necessity's mother.
Well, it seems the US government isn't too comfortable with that and tries (german link) to make (german link) the EU abandon that project. Naturally the EU doesn't like depending on a US-monopoly for such an important system.
"By the way if anyone here is in advertising or marketing... kill yourself." -- Bill Hicks
The reality is that in the time period since S/A was turned off many businesses have become dependent on the GPS. If S/A were to be turned back on worldwide, then that would provide one more reason to oppose the war. COnsidering the current political climate, both in the US and worldwide, I can't see this happening.
Maybe the French has threathened to veto? ;)
All dumbs jokes aside, EU really really needs to get a GPS system of our own. We should of course let the US use it, and use the original GPS when appropriate (for example extra accurcy or if one fail etc). It is fairly dumb to give away so much power to a foreign military.
Isn't that a bit like saying. It isn't your car - the money used to buy it was given to you by your employer.
Well, no.. its more like you split the cost of your car and its maintainence with 200 million other people. And also you elected a driver and split the cost of this as well. You're not allowed to drive the car, but you can be one of the mechanics but you have to give up some of your rights as a passenger. You also have some input as to where the driver takes you, but this is split between all the people as well. This might have to be a larger vehicle, because 200 million people don't fit that easilly into a car; in which case everyone has to spend a little bit more.
#!/
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.
French Fries--> Freedom Fries--> Democracy Fries--> Democracy but don't vote against us Fries--> Dictatorship Fries!