Posted by andreas from dtm2-t9-2.mcbone.net (62.104.210.101) on Wednesday, January 15, 2003 at 4:06AM :
Jam session ahead ?
3 articles
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Iraq Can Jam Guidance Of US Smart Weapons
By Knut Royce and Earl Lane
1-14-3
Iraq has jamming equipment potentially capable of knocking some of America's "smart" weapons off course, according to a U.S. government official with access to intelligence reports.
The official said this week the Iraqis have obtained at least a limited number of transmitters that can jam signals from the satellite-based global positioning system or GPS. The satellite signals are used to guide bombs called JDAMs (Joint Direct Attack Munitions) to their intended targets with precision.
"The question is how will they (the Iraqis) implement this and how effective they would be" at sending U.S. bombs astray, said the official, who asked not to be identified.
"Of course we are concerned," said Air Force Maj. Gen. Dan Leaf, director of operational capability requirements for the Air Force. But, he added, "Any adversary or potential adversary of the United States betting their future on GPS jammers is making a serious miscalculation." He said he was confident the Pentagon has effective means to counter the jamming threat, including alternate weapons such as laser-guided bombs.
The use of precision-guided bombs and missiles has been cited by Pentagon officials as a way to minimise civilian casualties in any attack on Iraq, particularly in densely populated areas like Baghdad. If Iraq were able to send some of the GPS-guided weapons off course, it could increase civilian casualties and spur regional criticism of a U.S. attack on Iraq.
Specialists, in and outside of government, have long noted the potential vulnerability of GPS-guided bombs to jamming. "If I was going to be bombarded with weapons guided by GPS, I would be out there looking for jammers too," said John Beukers, a radionavigation expert in Vero Beach, Fla. "It's not rocket science to build these things."
A Russian designer unveiled a small, 4-watt jammer at the 1997 Moscow Air Show that is said to be capable of disrupting GPS signals over an area about 100 nautical miles in radius.
The global positioning system, developed for the U.S. military, consists of a constellation of 24 satellites that continuously beam navigation signals that can be used by anyone with the proper receiver. The satellites transmit two signals, one available to civilian users, including commercial airliners, to determine their position within a distance of a few metres. The second signal, for use by the military, is encrypted. The Air Force placed GPS receivers on previously "dumb" gravity bombs as a way to enhance their accuracy. Once dropped from an aircraft, the bombs use GPS signals to locate a specific geographical location up to 15 miles from the drop site. GPS-guided JDAMS bombs were used in Kosovo and also in Afghanistan.
The GPS signals from the satellites are weak and can be overwhelmed by a broadband transmitter that generates enough "noise" at the right wavelengths, experts said. "I would tend to believe that you could jam those encrypted signals with enough power," said Linn Roth, president of Locus Inc. of Madison, Wis., a maker of radionavigation products. "Those signal levels are so low."
The military also uses the civilian signal to help home in on the military signal, another complication that could make the GPS-guided bombs vulnerable, specialists said.
Leaf said the Air Force has given GPS jamming "a lot of thought for a long time." He said the Air Force has run tests, including two recently, to help better understand how aircraft and weapons perform in the presence of jammers.
While JDAMS are "GPS-aided," Leaf said, they also have backup inertial navigation systems that "will still be precise enough for almost any target that we face." But he said the Air Force prefers the extra precision that GPS provides. John Pike, director of GlobalSecurity.org, a military research group, said an inertially guided bomb has an accuracy of about 100 feet, substantially less than GPS.
Leaf said jamming can be countered by changing the location of GPS-receiver antennas on the bombs to make them less vulnerable. Pike said placing directional antennas on the bombs "will give you a hundred-fold improvement" in ability to receive the weak satellite signals. "It is not clear which, if any, platforms or munitions have been fitted with such antennas," Pike said. Leaf declined to go into detail on specific countermeasures.
Pike said the military also could use airborne sensors to locate any GPS jammers and quickly destroy them with homing missiles, he said. Leaf said there are methods for silencing jammers. "If my jersey said GPS jammer operator, I wouldn't be real secure of my future," Leaf said.
A longer-term fix is to substantially increase the power of the GPS signal to make it less susceptible to jamming, Pike said. But that will require launching a next generation of satellites, a costly proposition that has not been budgeted.
© Al Nisr Publishing LLC - Gulf News Online
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FOX SPECIAL REPORT WITH BRIT HUME January 10, 2003
Satellite Jamming
In-Depth Coverage
SNOW: Thousands of Marines from Camp Lejeune in North Carolina will be leaving for the Persian Gulf in the next few days as the U.S. military build-up continues. But there is a new wrinkle that may jam some possible U.S. war plans.
Fox News Pentagon correspondent Bret Baier explains.
BRET BAIER, FOX NEWS PENTAGON CORRESPONDENT (voice-over): The U.S. military is working hard to make sure its satellite-guided bombs could hit their targets in Iraq. Why? Senior defense officials tell Fox the Iraqis may have purchased several hundred jamming devices like this from a Russian firm. Electronic devices used to jam a satellite signal in order to make Smart bombs confused.
Fox News has obtained this photograph that comes from a Russian air show where the devices were being sold. The map on the left is of Iraq. And the circles on the map are potential placement options for the jamming devices. Senior defense officials concede that up to 80 percent of the bombs that is would be used in Iraq would be satellite-guided. Analysts say global positioning system jammers or GPS jammers could make a war with Iraq messy.
JOHN PIKE, DIRECTOR, GLOBALSECURITY.ORG: If the satellite signal is interrupted by these jammers, that the bombs are not going to be as accurate, you're going to hit fewer of the intended targets, more unintended orphanages and hospitals going to be hit, and I think that's basically part of Saddam's strategy.
BAIER: Secretary of State Colin Powell asked today about the possible Iraqi purchase of the GPS Jammers, said he has seen the reports and, if true...
POWELL: We, of course, would be concerned.
BAIER: Concerned, but not deterred, according to senior defense officials. They say the Air Force has been working hard on the GPS jamming issue for months and is looking for ways to overcome the effects. Weapons like the satellite-guided J-Dams have their own internal navigation to at least partially be able to overcome even effective jamming. And laser- guided bombs are also an option like the ones used extensively in Afghanistan.
MAJ. GEN. DAN LEAF, U.S. AIR FORCE: I would not put much stock, if I were any potential adversary for the United States, in betting the farm, if you will, on GPS jamming. We're ready right now to encounter and address and be successful even in a GPS jamming environment.
BAIER: Meantime, more of the military is on the move. Three Navy ships left Norfolk, Virginia today to pick up thousands of Marines in North Carolina this weekend. Seven thousand Marines from Camp LeJeune have been ordered to embark and prepare to deploy to the Persian Gulf.
Meantime, psychological operations continue in Iraq. We have seen a number of different ways for this to happen. For example, leaflets, commando solo radio broadcasts in Iraq, even direct telephone calls to Iraqi military personnel. Tonight, senior defense officials confirmed to Fox News that the U.S. military is e-mailing some of those Iraqi military agents, military soldiers saying that they should defect, they should not be on Saddam's side, and whatever they do, they should not use weapons of mass destruction or they will be tried after a potential war with Iraq -- Tony.
SNOW: Bret, thank you.
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January 11, 2003
A Weapons Jam?; Saddam may be able to knock U.S. 'smart' bombs off course
In-Depth Coverage
By Knut Royce and Earl Lane
Washington - Iraq has jamming equipment potentially capable of knocking some of America's "smart" weapons off course, according to a U.S. government official with access to intelligence reports.
The official said this week the Iraqis have obtained at least a limited number of transmitters that can jam signals from the satellite-based global positioning system, or GPS. The satellite signals are used to guide bombs called JDAMs (Joint Direct Attack Munitions) to their intended targets with precision.
"The question is how will they [the Iraqis] implement this and how effective they would be" at sending U.S. bombs astray, said the official, who asked not to be identified. "Of course we are concerned," said Air Force Maj. Gen. Dan Leaf, director of operational capability requirements for the Air Force. But, he added, "Any adversary or potential adversary of the United States betting their future on GPS jammers is making a serious miscalculation." He said he was confident the Pentagon has effective means to counter the jamming threat, including alternate weapons such as laser-guided bombs.
The use of precision-guided bombs and missiles has been cited by Pentagon officials as a way to minimize civilian casualties in any attack on Iraq, particularly in densely populated areas like Baghdad. If Iraq were able to send some of the GPS-guided weapons off course, it could increase civilian casualties and spur regional criticism of a U.S. attack on Iraq. Specialists, both in and outside of government, have long noted the potential vulnerability of GPS-guided bombs to jamming. "If I was going to be bombarded with weapons guided by GPS, I would be out there looking for jammers too," said John Beukers, a radio-navigation expert in Vero Beach, Fla. "It's not rocket science to build these things."
A Russian designer unveiled a small, 4-watt jammer at the 1997 Moscow Air Show that is said to be capable of disrupting GPS signals for more than 100 miles in any direction.
The global positioning system, developed for the U.S. military, consists of a constellation of 24 satellites that continuously beam navigation signals that can be used by anyone with the proper receiver. The satellites transmit two signals, one available to civilian users, including commercial airliners, to determine their position within a distance of a few meters. The second signal, for use by the military, is encrypted.
The Air Force placed GPS receivers on previously "dumb" gravity bombs as a way to enhance their accuracy. Once dropped from an aircraft, the bombs use GPS signals to locate a specific geographical location up to 15 miles from the drop site. GPS-guided JDAMs bombs were used in Kosovo and also in Afghanistan.
The GPS signals from the satellites are weak and can be overwhelmed by a broadband transmitter that generates enough "noise" at the right wavelengths, experts said. "I would tend to believe that you could jam those encrypted signals with enough power," said Linn Roth, president of Locus Inc. of Madison, Wis., a maker of radio-navigation products. "Those signal levels are so low."
The military also uses the civilian signal to help home in on the military signal, another complication that could make the GPS-guided bombs vulnerable, specialists said.
Leaf said the Air Force has given GPS jamming "a lot of thought for a long time." He said the Air Force has run tests, including two recently, to help better understand how aircraft and weapons perform in the presence of jammers.
While JDAMs are "GPS-aided," Leaf said, they also have backup inertial navigation systems that "will still be precise enough for almost any target that we face." But he said the Air Force prefers the extra precision that GPS provides. John Pike, director of GlobalSecurity.org, a military research group, said an inertially guided bomb has an accuracy of about 100 feet, substantially less than GPS.
Leaf said jamming can be countered by changing the location of GPS-receiver antennas on the bombs to make them less vulnerable. Pike said placing directional antennas on the bombs "will give you a hundred-fold improvement" in ability to receive the weak satellite signals. "It is not clear which, if any, platforms or munitions have been fitted with such antennas," Pike said. Leaf declined to go into detail on specific countermeasures.
Pike said the military also could use airborne sensors to locate any GPS jammers and quickly destroy them with homing missiles. Leaf said there are methods for silencing jammers. "If my jersey said 'GPS jammer operator,' I wouldn't be real secure of my future," Leaf said.
A longer-term fix is to substantially increase the power of the GPS signal to make it less susceptible to jamming, Pike said. But that will require launching a next generation of satellites, a costly proposition that has not been budgeted.
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