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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."
Or use differential GPS, and get accuracy to a few tens of millimeters.
Would be interesting to know what the EU would do with Gallileo at this moment in time. I dare say they would follow the US lead, I suppose...
...by having the satellites deliberately and randomly return inaccurate information on where they are.
;)
Isn't that supposed to be terrorism ?
Karma cannot be described by words alone.
My guess is that for high-precision locations, the Iraqis already measured them with high accuracy, while for, say, infantry navigation all you really need is 100m accuracy. (Even less for armored forces, of cource)
And given the air threat, I also doubt their forces will change their localtions too much; if it's camouflaged enough to survive the initial attacks, it will probably stay put.
Working for necessity's mother.
Civilian planes use GPS, don't they?
What about other critical systems like police, ambulance, fire brigades and so on??
There are plans for building a similar system to GPS in Europe so that we are not too much depending on the american empire. The following page nicely explains the concept. More is available here . This is technically very interesting and should open up new possibilities for navigation. Furthermore being constructed jointly by many partners and nations we can be reasonably sure that it can not be compromised by one weak leader.
Googlefight "Slashdot Troll" against "BSD is dying" 303:229. BSD thus cant die.
a) A sane person would rely on GPS because they may not be very good with compass and map, or they may have cordinates for something not marked on a map. When driving at speed the margin of error is negligible, and it enables you to navigate through featureless terrain such as desert playa which are impossible to use a map in.
v)Well...I would walk to a point which I knew the exact location of and then do 10 or 15 GPS location checks to see what the margin of error was.
Did you really not know these answers or am I just feeding a troll?
"To any truly impartial person, it would be obvious that I am right."
There is a better alternative to GPS named STDMA (Self-organizing Time Division Multiple Access). It is patented with U.S. Patent No. 5,506,587, which you may find HERE.
It is in use in marine navigation. See also HERE and for a tech overview HERE.
Apparently, the US has tried to suppress the system as it may well replace GPS because of better performance and other reasons; one can imagine wartime control may be of importance here.
There was a big discussion on one of the GPS newsgroups about this very fact - at the time of the last gulf war, civillian GPS units were cheaper, more plentiful, and had more features that the troops wanted/required than the more cumbersome military GPS units.
One of the soldiers was talking about it in the group and basically said the military units were limited to showing long/lat and doing goto-waypoint distance/direction operations. At the same time, civillian units had mapping capabilities, easy to use graphic displays, and were about 1/2 the size.
As other posters have said, it's possible to adjust the SA signal geographically, so they could degrade the signal in the middle east without changing anything in north america. This is the first step that seems logical.
Alternately, they could leave SA off alltogether, and just jam the GPS signal in the area that they are performing operations - the GPS signal is relatively weak and an ECM aircraft could easily block hundreds of miles of GPS reception while flying out of range of ground-based weaponry.
N.
"Nothing strengthens authority so much as silence." - Charles de Gaulle
Even if it was, it would still remain under the control of the Russian military, just as GPS is under the control of the Pentagon.
The whole point (well, one of the major ones, anyway) of Galileo was to create a network which wouldn't be under military control, and so could be relied upon not to be switched off at inconvenient moments.
I rather like to idea of getting a bunch of people together - going round to military HQ and saying - "can we have our bomb back?"
You know..if there was a medal for ignorance, I think you just would have won the gold.
A lot of countries don't have the technology to build satellites, or the money to research said technology..thus, they rely on the existing infrastructure. And some people rely -extensively- on accurate GPS measurements..sea-faring vessels, civilian aircraft, the list goes on. Think of how they might be affected if they weren't even aware this change was taking place; particularly if they were conducting research in a remote location, and relied upon GPS to..well..figure out where the hell they are.
Send up your own satellites indeed. I'm suprised an American can actually speak those words, yet still be amazed why they're so hated outside their own country.
On the contrary. The Iraqis' biggest weakness in the first Gulf War was their inability to navigate through the open desert. There's very little in the way of navigation aids out there, so it doesn't matter how well you know the country.
GPS is their ticket off of the roads, allowing them to do what we did-- go right through the unposted desert. My question is how much this signal will be degraded, and whether it will seriously hinder efforts at desert navigation.
Actually, most units have a 12-channel parallell receiver, so it can do a pretty job and narrow your
position within 9 meters. 4-channel GPS units are things of the past (or used sometimes when size
matters more than accuracy).
Also, there are a "new" addition to the GPS system called WAAS (wide-area-augmentation-system) which
uses differente sattelites (this ones being geo-stationary) to send differentials information about
the GPS's sattellites signals. This way, a civilian WAAS-enabled unit like mine (garmin etrex vista)
can have an accuracy of about 3 meters, in theory. I find WAAS pretty dodgy and dont tend to use it
much because of higher battery comsumption and higer CPU usage, for a small improvement in the
accuracy (I mostly use the GPS in the car, so...)
cheers.
``If a program can't rewrite its own code, what good is it?'' - Mel
THanks for the links. Very informative. In their it says that the US military has never degraded civilian service, neither during Gulf War I or during Kosovo. Though there are contigency plans to limit affectiveness for a specific area (from one of the links). Sounds good to me. But the important part is that it's never been done.
The interference sounds like a very serious issue as well.
Also, the US didn't annoucne anything--we still have no idea if the signals will be degraded or not. This all comes on the speculation of a German autoclub--no doubt the first group of people informed of US military policy.
Scott
that the US turned off SA in the first place to neuter the Galileo project by reducing its perceived need.
Well, the second time the US turned SA off was for that reason.
This article is really amusing because of the fact that the government actually turned SA OFF for the last Gulf War, as there was a shortage of military GPS receivers and soldiers were ordering civilian units mail-order.
retrorocket.o not found, launch anyway?
Is it really worth the money and the effort to send up an entire system so that coverage can be ensured during the say 2% of time when the GPS signals are distorted for military reasons?
Yes!! I work for a USA company that is working on Gallileo receivers. The higher precision and reliability of the Gallileo system will likely entirely supplant the other two GNSS systems.
In the FAA air traffic simulator where I work, we have recently done studies preparing for what would happen if the GPS satellites were disabled (on purpose or jammed from a terrorist). NATCA (the controllers union) has developed procedures for what to do when this happens. Most aircraft would fall back to their backup navigation systems, assuming such systems would work on the route they were currently on. Less than 2% would even need attention, and it would be minor intrusion at that -- just enough to get then to where they can fly on their own. Even in the future, when some of the current systems are removed, it won't be much more of a problem.
;)
So you can feel just as safe flying as you currently do
----- I hate sigs.
The method described does some signal conversion to extract useful information from the P code even when the A code (encryption) is not known. It uses an approximation of the A code and summing over time to extract useful information.
I for one couldn't care less if hikers' GPS accuracy is reduced to 100m, but for the industry I work in (Precision Agriculture), this presents a huge problem. Many of our clients used DGPS back in the day, and in some areas where it is freely available (along the coast, mostly), still do. However, most do not. 3m was already bad enough, but 100m is a real problem. I'm sure there are other industries being affected by the use of SA as well.
I've built up so much character I have an alter-ego
Here's the dirty little secret. Many soldiers use their own civilian GPS devices, b/c they have better features. So, I'd bet there are more American and British soldiers using civilian GPS than there are Iraqis. I doubt GPS will be degraded, and if so, it will be brief.
Or during full night either, except using an artificial horizon on your sextant (bubble sextant), requires a big ship's stability.
"Night" sights for celestial navigation are usually made when the sun is some (5~10) degrees under the horizon, so that both the stars and the horizon line are visible. This allows (with ex. 3 stars) a full position to be determined in a few minutes.
The moon may also be used, but precision is usually bad, because of unprecise (complex and rapidly evolving) ephemerids (almanac) and raised horizon (glare) under the moon at night.
By day, if both the ship's and sea current's course / speed are steady, the classical method of the running fix allows the ship's position and course to be determined using only sun sightings.
This may be performed (provided that sun and horizon are clearly visible) using only a precise timepiece, a sextant and special "sight reduction" tables. The latter item is preferably replaced with a programmable calculator, which will run for tens of hours on a single set of batteries, although the tables should be on board and understood.
This old technique is not as fast or as precise as the GPS, and requires a clear sky, but does not depend on the ship's power supply or on the fast-emptying batteries of a hand-held GPS unit, and because of this is mandatory for navigation on Class 1 yachts (allowed on the high seas).
This follows the sailors' habit of never discarding old-but-working methods, especially if they are more robust than new-fangled ones.
I don't think the army is too worried about DGPS. It would solve the civian problems of accessing accurate GPS data, but not the military problems. Why? Because the DGPS station would need to have a transmitter, and it would have to remain at a very precisely fixed geographic location, and transmitters don't last long in war - especially if they are in fixed locations.
I know the US is actively looking to find ways to deny potential enemies access to 3rd party satellite services. If the EU launces their own GPS system, they would be expected to play ball with the US and turn it off in areas where the US military is operating. If they don't the satellites could be considered a military device (since they would be used by a military), and they would probably be jammed at the least, and if that doesn't work then they could be targetted. I'm guessing most corporations that own satellites would just play ball - those satellites cost big money and I doubt their insurance protects against US anti-satellite weapons. Government-owned satellites might be a different story - depending on whether the foreign government wants to make the political move of standing up to the US.
Keep in mind that providing targetting data to a military is hardly a neutral stance. If the US provided military GPS receivers to Chechen rebels, you can bet the Russians would be ticked.
www.faa.gov has already got NOTAMs posted regarding inaccurate GPS readings and not to rely solely on GPS for IFR flight.
sPh
Now correct me if I'm mistaken here, but wouldn't deliberately decreasing the accuracy of GPS signals essentially create a further handicap for this person who uses the equipment in his day to day life to function more like a "normal" person. Somehow that just seems wrong to me.
And on the up-side, it's great news for people who don't want the rental car companies tracking where they drive.
File under 'M' for 'Manic ranting'
The early news discussions were predicting the war would cost about $200 billion. That's about $1000-2000 per American taxpayer. Of course, that doesn't count the cost of taking that money out of the civilian economy, which had better things to do with it. If they'd really wanted to take out Saddam because he was a mean nasty ugly guy, a Mossad hit squad could have probably done it for $5-10M, and the CIA could have probably done it for well under a billion, without the need to kill thousands or hundreds of thousands of Iraqi civilians or risk the lives of large numbers of US soldiers.
Bill Stewart
New Fast-Compression-only CPR http://preview.tinyurl.com/dy575ks