Chris Lee FRS April 2004 Prof. Groth

GPS Basics Made up of a constellation of 27 satellites Each of these satellites are about 12,000 miles from the Earth Set up so that at any given time, at least four satellites can be picked up for navigation Originally developed by the U.S. military, but quickly branched out into civilian use

Communications Two things need to be communicated 1. The locations of at least three satellites above the receiver. 2. The distance between the receiver and each of the satellites. Sent in form of radio waves, traveling at the speed of light Waves are high in frequency, but low in power.

GPS Satellite

Distances Distances are found by measuring the amount of time for the signal to travel from satellite to receiver. It measures the time delay of pseudo- random code. NAVSTAR

Civilian Jammers An article in hacker mag Phrack reported how to make a low-cost GPS jammer. The materials for this product could be easily obtained from electronics stores.

“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." -Phrack Magazine

D.O.D. This article made a big enough impact that the Defense personnel even issued statements. Not a current threat to aircraft or military functions. Can affect commercial use.

The “But” Richard Langley, a GPS expert and professor of geodesy at the University of New Brunswick in Fredericton, New Brunswick said that these jammers would not be effective against aircraft from the ground. BUT if used onboard a plane, it would increase the range/effectiveness of the jammer.

Why shouldn’t it affect military operations? Civilian GPS operates at MHz Military GPS operates at MHz. --Statements by Phrack Magazine

James Hasik Consultant/author of The Precision Revolution: GPS and the Future of Aerial Warfare disagrees with Phrack. Says the Phrack jammer is targeted at GPS signal, known as “C/A code.” Could be a threat to military GPS because they must get C/A signal before getting military, “P(Y) code.”

The Pentagon They don’t “at the moment” view these jammers to be a threat. Pentagon GPS experts do not believe that they will affect flight safety for commercial operations.

Iraqi Military Jammers There have been reports that the Iraqis have acquired 200 jammers from Russian firms. These would instantly cause civilian casualties.

Will they affect U.S. operations? Some say yes, but the fact is that the U.S. has anti-jamming technology. We surely have other things to combat these jammers. Odds are it’s basic anti- jammers. Then I started thinking, maybe it’s something really cool that I don’t even know about yet.

Is the U.S. worried about these jammers? NO! The Iraqi jammers are literally broadcasting their locations. If we were worried about them, we could take them out with relative ease.

Tricks for Iraq There is one trick that the Iraqis could play with these jammers. They could put jammers on top of mosques and residential buildings. If we tried to attack the jammers, we would be taking the lives of civilians. This would also give the Iraqis propaganda to use against the U.S. since they wont win a military war. Can we handle this type of situation? Of course…

Aviaconversiya Ltd. Reportedly is the Russian company which sold Iraq their 200 jammers. In March 2003, U.S. Army awarded about $200,000 in contracts to this company. We bought jammers in order to test their capabilities

How do we get around jammers? Boeing has developed anti-jamming technology. That was back in Imagine what we have now.

JDAM Tail Kits JDAM (Joint Direct Attack Munition) Use GPS and Inertial technology. May be more navigation systems in them that haven’t been made public.

The Bottom Line There is no realistic way that Iraq, or Russia for that matter, could jam our GPS system in a way that would significantly affect the accuracy of our JDAMs.