March 22,2008: The U.S. Navy has become the latest victim of electronic fratricide. In Iraq, its Silver Hawk UAVs [PHOTO] are getting disabled by interference from other military electronics. This problem was first noted back during the 1990 campaign to liberate Kuwait. There it was discovered that certain combinations of airborne jammer frequencies could trigger an involuntary launch of Patriot anti-aircraft missiles, as well as some less catastrophic, but equally unexpected events. Investigation of these incidents revealed something electronic warfare experts have been warning of for a long time. With so much exotic new gear, capable of putting out so many different signals, and in a huge number of combinations (which creates even more new electronic signals), there was no way to knowing what kind of impact this would have on existing military, and civilian, electronics. Throughout the 1990s, the problem only got worse. This became obvious as there were increased incidents of military electronics tests trashing, or playing with, nearby civilian electronic devices.

The military has been seeking solutions, because it's important for military equipment, especially communications and control systems, not to suffer electronic interference. In Iraq, is was quickly discovered that Warlock (a jammer that shut down enemy use of wireless signals to set off roadside bombs) also interfered with some military equipment, including some radios. This was not good.

The latest victim is the U.S. Navy Silver Fox UAV. This aircraft weighs 22 pounds (with a four pound payload) and can fly as high as a thousand feet. Its eight foot wings are easily removed from the fuselage and the UAV can then be carried around in a 60"x14"x15" container. If the wind is strong enough, the Silver Fox can be launched by hand, but normally it is propelled into flight via compressed air from a portable launcher. The UAV lands by just stopping the engine when it's low to the ground. The UAV is light enough to just bounce when it hits the ground. A model aircraft engine keeps it in the air up to five hours per sortie. The aircraft is maneuvered via radio commands via a laptop computer. It can either be controlled by the operator, or simply instructed to go from one way point to another (using an onboard GPS and flight control software.) It can fly at speeds of up to a hundred kilometers an hour (about 27 meters a second). It's small enough to provide a hard to hit target for enemy troops firing at it. In any event, it's engine is hard to hear when the UAV is higher than 500 feet. At night, it's pretty much impossible to detect from the ground. Each Silver Fox costs about $10,000.

The navy uses Silver Fox in Iraq to support its Riverine units. But most of the Riverine missions involve some truck convoy action, and that's where the Silver Fox is used to provide extra eyes for the sailors in the trucks. The Silver Fox did not always have problems with jammers and other electronic warfare equipment. But this stuff constantly changes, in response to whatever the enemy is using. The navy is looking at several fixes. In the meantime, there are some limitations on how Silver Fox can be used.