GPS control contention – jamming and anti-jamming

The U.S. military needs to overcome the weakness of GPS jamming

GPS signal jammer work by sending a signal that interferes with the communication between a satellite and GPS receiver. It’s a relatively simple operation, with relatively short-range effects. Thus far, cell phones used by civilians and troops and some military equipment have been put on the fritz by the disruption attempts.

There are other, somewhat similar anti-drone tools in existence. West Point cadets used a demonstration cyber-rifle as part of training this summer, and the Battelle Drone Defender rifle was spotted in Iraq earlier this year. Jamming drone signals, and doing so with rifles, isn’t the only way to disable quadcopters. Other tools range from net bazookas to trained police eagles.

If it works just right, the GPS jammer can cut off a satellite-guided bomb’s ability to guide itself to target. The bomb simply continues hurtling towards the ground in the direction it was when it lost contact with a satellite.

However, these weapons have other means of guiding themselves in the event of jamming. Take the Joint Direct Attack Munition (JDAM), a guidance kit that’s strapped to older, “dumb” bombs to make them more accurate. In addition to GPS, the JDAM kit comes equipped with an Inertial Navigation System (INS), which measures a bomb’s acceleration and uses the information to plot its way to a target. In the event a JDAM’s GPS signal is successfully jammed, it can rely on its INS to guide it, although accuracy is reduced from 5 to 30 meters.

The U.S. Air Force itself has been conducting GPS signal jammer exercises — one such exercise is scheduled for March 10-14, 2003, in the Yukon MOA near Fairbanks, Alaska. There has been at least one well-documented case of unintentional jamming, and the U.S. Federal GPS Policy makes clear that GPS, while now supervised by a joint inter-agency governing board, is subject to control by the National Command Authority. That means the President can decide to jam the entire system if he decides it is necessary

A South Korean government source on Wednesday said they are keeping a close eye on the communist country as they understand that North Korea has developed a GPS jammer by copying a Russian device, and has been looking to export it to the Middle East.

The source added that North Korea has been promoting the GPS jammer to several Middle Eastern countries by offering a better price than the Russian device.