September 23, 2007: The U.S.
announced that it can now degrade the GPS signal in a small area, and will no
longer buy GPS satellites equipped to degrade the signals planet wide. The
degraded signal (originally the "civilian" signal) is only accurate to within
100 meters, while the most accurate signal (originally the "military" signal)
is accurate to ten meters (31 feet) or less (with additional ground equipment.)
The newly announced capability can degrade the civilian signal to a different
degree. Since 2000, the only signal available has been the military one, so
that more commercial applications could be implemented. To access the military
signal, you need special codes. But since 2000, everyone got the military grade
signal, without needing special access codes.
Russia, the European Union and
China have been developing competitors for GPS, but so far these efforts have
spent a lot of money, and not produced any real competition. This new
announcement about GPS accuracy was meant to reassure non-U.S. users that they
would never have to worry about losing the 10 meter signal. The U.S. Department
of Defense has also spent a lot of money on developing ways to deal with enemy
attempts to jam the GPS signal, and creating the ability to degrade the signal
for non-U.S. users in a combat zone.
