U.S. Government May Reduce Non-Military GPS Accuracy



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.


Drivers whose cars are equipped with a global positioning system (GPS) may be the first to know when war breaks out against Iraq, a German automobile club said Tuesday.
The satellite-based system, funded and controlled by the US Department of Defense, provides specially coded signals that can be processed to enable the receiver to compute their position, speed and time.

Its primary function is in navigation for aircraft, ships and vehicles such as taxis.

But while there are thousands of civil users of GPS worldwide, the system was designed for, and is operated by, the US military.

The German automobile club AvD said experts fear that just before military action against Iraq, which seems likely to start later this week, the signals will be encoded in order to make them less accurate.

The argument is that by doing so, the enemy -- in this case Iraq -- would not be able to exploit the system to pinpoint US-led forces sweeping into the country.

Currently, the GPS system has an accuracy to within around five metresfeet), but AvD said it could be reduced to more than 100 metres.

Not a big problem for a ship at sea, perhaps, but bad news for drivers in crowded cities.

"German drivers could potentially notice the start of the war quicker than the chancellor," AvD spokesman Jochen Hoevekenmeier quipped.

He said some two million German cars are equipped with a navigation system, most of them newer versions which would be unaffected.

However around a third, particularly those fitted with an older or updated GPS system, could find it has gone haywire.

It urged drivers to take precautions and bring along an old-fashioned map.



Off 'Motherfuckin' Topic Elite
Fucking intelligent, but does seem to be taking the fairness out of war too.


New Member
I actually have an FAA adivsory for a GPS approved approach here where I am that addresses the accuracy issue...

....GPS accuracy is not affected and any units approved for such approaches are still "legal" for the approach....

..this from a briefing post at DM Aviation (where I fly out of).