Fire up the space junk - Exterminate the brutes!
GPS Jamming No Silver Bullet For Potential Adversaries
An F-16 Fighting Falcon pilot with the 79th Fighter Squadron at Shaw Air
Force Base, S.C., releases a 2,000-pound Joint Direct Attack Munition.
JDAMs use the global positioning system for precision guidance. Iraq and
other potential adversaries may have the ability to jam GPS signals, but
Air Force war planners are not too worried about the effect of jamming on
precision munitions. (Photo by Tech. Sgt. Michael Ammons)
by Master Sgt. Scott Elliott
for Air Force News
Washington - Feb 21, 2003
Iraq and other potential adversaries may have the ability to jam global
positioning system signals, but Air Force war planners are not too worried
about the effect of jamming on precision munitions. In fact, it is a
challenge they have been anticipating for a long time, and they are
confident in their ability to overcome it.
"From the day we built GPS, we've been working on ways to overcome
jamming," said Lt. Col. John Carter, chief of space requirements at the
Pentagon. "We're very confident we can do that."
GPS is a constellation of satellites that emit electronic signals while
orbiting the Earth. A GPS receiver gathers the signals from multiple
satellites overhead, then triangulates those signals to calculate its
precise location. Those receivers can be hand-held or mounted in ships,
aircraft, vehicles and precision guided munitions.
The United States routinely installs GPS guidance packages in standard 500-
1,000- and 2,000-pound bombs to create the Joint Direct Attack Munitions.
The JDAM typically strikes within 13 meters of its target.
According to reports, Iraq has acquired several Russian-made transmitters
capable of jamming the GPS signal.
In general terms, someone could "jam" a radio signal by transmitting a more
powerful signal on the same frequency. Carter equates the practice with
trying to listen to a conversation on the other side of the room while
another person shouts in your face.
While the tactic may seem easy to accomplish, Carter said he would not
encourage anyone to take the job.
"Anyone who (transmits) on the battlefield can be found, and anyone who can
be found can be targeted," he said. "When the bad guys are picking jobs,
(they) don't want to pick 'GPS jammer.'"
A GPS jammer is not a silver bullet to prevent precision bombardment,
Carter said, because the Air Force has more than one way to put steel on
target.
"Oftentimes we get sucked into looking at individual engagements, and
warfare is not an individual engagement," he said. "It's the sum of all the
actions you take. We have a lot of arrows in our quiver."
Those include the inertial navigation system within the JDAM, its primary
navigation system, which is fully capable of guiding the weapon to its
target. The Air Force also employs laser- and optically-guided munitions,
as well as free-falling bombs.
The Air Force also is looking ahead to ensure future GPS satellites are
more jam-resistant, beginning with the current crop of modified GPS IIRs.
"One of the features of the modification is something called flexible
power, which increases the power level radiated from the GPS," said Peter
B. Teets, undersecretary of the Air Force and chief of the National
Reconnaissance Office.
That power increase will provide some anti-jam capability, but Teets said
the real improvement will come when the GPS III is introduced in about 10
years.
"We recognize the fact that GPS can be jammed," Teets said. "We're taking
steps to make it much more jam-resistant on the satellite side, on the
control-element side and on the user-equipment side.
"I think we're doing the necessary smart things to enable GPS to serve us
well," Teets said.
http://www.spacedaily.com/news/gps-03g.html
