GPS jamming no 'silver bullet' for potential adversaries
by Master Sgt. Scott Elliott
Air Force Print News
WASHINGTON -- 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
In fact, it is a challenge they have been anticipating for a
long time, and they are confident in their ability to overcome
"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
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
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
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
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
"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
"I think we're doing the necessary smart things to enable
GPS to serve us well," Teets said.