Subject: [NEXTEL-1] Homemade GPS jammers raise concerns

From: Rick Parrish <[email-masked]>
Date: Sat, 18 Jan 2003 19:08:34 -0600

Homemade GPS jammers raise concerns

http://computerworld.com/securitytopics/security/story/0,10801,77702,00.html

By Bob Brewin

JANUARY 17, 2003

Government officials and communications experts are assessing the public
safety and security implications of a newly posted online article that provides
directions for making cheap devices that can jam Global Positioning System
(GPS) signals.

Information in the article that appears in the current issue of the online
hacker magazine Phrack potentially puts at risk GPS devices used for commercial
navigation and military operations, authorities said.

The Phrack article provides a detailed guide to building a low-cost, portable
GPS jammer out of components that can be easily obtained from electronics
supply houses. According to the article, the "onslaught of cheap GPS-based
navigation (or hidden tracking devices) has made it necessary for the average
citizen to take up the fine art of electronic warfare." Electronics and GPS
experts who read the article this week called it technically competent and
said amateurs with a certain amount of technical skill could build a GPS
jammer from the plans.

Although the article said the jammer is designed to work only against civil-use
GPS signals broadcast on the frequency of 1575.42 MHz and not the military
frequency of 1227.6 MHz, James Hasik, an Atlanta-based consultant and author
of the book The Precision Revolution: GPS and the Future of Aerial Warfare,
disagreed.

Hasik said that while the Phrack jammer is targeted at civil GPS signals,
known as the C/A code, it could also threaten military systems, since "almost
all military GPS receivers must first acquire the C/A signal" before locking
onto the military signal, known as the P(Y) code.

Hasik said that GPS receivers are especially vulnerable to jamming because
of low signal strength after traveling 20,000 miles through space from GPS
satellites.

The U.S. Department of Defense, which faces the possibility of having its
GPS-guided weapons come up against Russian-made GPS jammers in Iraq, has
antijamming technology at its disposal. Still, Defense officials viewed the
Phrack article with concern.

Air Force Lt. Col. Ken. McClellan, a Pentagon spokesman, said the implications
of homemade jammers described in the article are "somewhat serious" because
the use of such jammers "could disrupt commercial operations."

McClellan said GPS experts at the Pentagon do not "at the moment" view homemade
jammers as a hazard to flight safety for commercial aircraft or ship operations,
"but rather a nuisance."

The Federal Aviation Administration is developing a nationwide GPS-based
precision landing system. And the Coast Guard operates a GPS-based maritime
navigation system on both coasts, the Great Lakes, inland waterways and Hawaii.
Bill Mosley, a spokesman for the Department of Transportation, the parent
agency of the FAA and the Coast Guard, said his department is well aware
of the threat posed by GPS jammers.

The DOT's John A. Volpe Transportation Systems Center, in Cambridge, Mass.,
prepared a report in August 2001 that said, "Some jamming devices/techniques
are available on the Internet and proliferation will continue, because a
single device that could disrupt military and civil operations worldwide
would be attractive to malicious governments and groups."

As a result of that study, Mosley said, Transportation Secretary Norman Mineta
last March ordered an "action plan" to protect civilian GPS signals and users
by, among other things, "the transfer of appropriate antijam technology from
the military to civil use." Mosley was unable say whether that technology
transfer has occurred.

Richard Langley, a GPS expert and professor of geodesy at the University
of New Brunswick in Fredericton, New Brunswick, called the implications of
home-brew GPS jammers "scary." But he expressed doubt that the Phrack jammer
would be very effective against aircraft when used from the ground. However,
Langley noted that if a terrorist used the jammer from on board an aircraft,
it would extend the range and "hence the effectiveness of the jammer."

James Miller, program manager for GPS at United Air Lines Inc., said the
loss of a GPS signal in a commercial aircraft wouldn't "cause a catastrophic
event," because airliners operate with multiple navigation systems. But loss
of a GPS signal by general aviation aircraft flying solely on GPS could be
"quite challenging," he said.

Warren Morningstar, a spokesman for the Aircraft Owners and Pilots Association
in Frederick, Md., said general aviation pilots don't use GPS as their sole
navigation source and called the potential of jamming a "nuisance" rather
than a safety hazard.

"You need to take it seriously anytime there is publicity about things that
could disrupt the critical infrastructure," said Mike Swiek, executive director
of the U.S. GPS Industry Council in Washington. But, Swiek said, "there is
no need for panic. All the GPS systems are monitored for any type of interference."
Swiek noted that while "any garden-variety radio engineer" has the knowledge
to build a GPS jammer, there have been few reports of any attacks against
GPS systems.

Gabe Neville, a spokesman for Rep. Joseph Pitts, (R-Penn.), co-chairman of
the House Electronic Warfare Working Group, said news of the Phrack story
about jamming indicates that GPS jamming technology is "easily available"
and that the Pentagon needs to beef up its electronic warfare research and
development budget. But Neville said he doubts a homemade jammer could cause
as much damage or disruption as systems acquired and operated by foreign
governments.

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---

From: Rick Parrish <[email-masked]>
Date: Sun, 19 Jan 2003 03:19:30 -0600

Rick Parrish wrote:

By Bob Brewin

JANUARY 17, 2003

<SNIP>

Although the
article said the jammer is designed to work only against civil-use GPS signals
broadcast on the frequency of 1575.42 MHz and not the military frequency
of 1227.6 MHz, James Hasik, an Atlanta-based consultant and author of the
book The Precision Revolution: GPS and the Future of Aerial Warfare, disagreed.

Please note the following addendum to the original Phrack article mentioned
above ...

"This device is also frequency agile, though not mentioned.

The current PLL setup will lock to any frequency between about 1.3 and 2.3
GHz (run the synth chip at 9 volts) in 5 MHz steps. You'll need to remove
the BPF and power amp though. It could be useful as an exciter in a 1.9 GHz
CDMA jammer.

With a simple electret microphone and deviation pot on the EXTERNAL setting
it will also function as a microwave surveillance bug."

-rick

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