Electronic counter-countermeasure

Ever since electronics have been used in battle in an attempt to gain superiority over the enemy, effort has been spent on techniques to reduce the effectiveness of those electronics. More recently, sensors and weapons are being modified to deal with this threat. One of the most common types of ECM is radar jamming or spoofing. This originated with the Royal Air Force's use of what they codenamed Window during World War II, which Americans referred to as chaff. It was first used during the Hamburg raid on July 24-25, 1943. Jamming also may have originated with the British during World War II, when they began jamming German radio communications. These efforts include the successful British disruption of German Luftwaffe navigational radio beams. In perhaps the first example of ECCM, the Germans increased their radio transmitter power in an attempt to 'burn through' or override the British jamming, which by necessity of the jammer being airborne or further away produced weaker signals. This is still one of the primary methods of ECCM today. For example, modern airborne jammers are able to identify incoming radar signals from other aircraft and send them back with random delays and other modifications in an attempt to confuse the opponent's radar set, making the 'blip' jump around wildly and become impossible to range. More powerful airborne radars means that it is possible to 'burn through' the jamming at much greater ranges by overpowering the jamming energy with the actual radar returns. The Germans were not really able to overcome the chaff spoofing very successfully and had to work around it (by guiding the aircraft to the target area and then having them visually acquire the targets). Examples of electronic counter-countermeasures include the American Big Crow program, which served as a Bear bomber and a standoff jammer. It was a modified Air Force NKC-135A and was built to provide capability and flexibility of conducting varied and precision electronic warfare experiments. Throughout its 20-year existence, the U.S. government developed and installed over 3,143 electronic counter-countermeasures to its array of weapons. ==Specific ECCM techniques==

The following are some examples of EPM (other than simply increasing the fidelity of sensors through techniques such as increasing power or improving discrimination): This method is also useful against barrage jamming in that it forces the jammer to spread its jamming power across multiple frequencies in the jammed system's frequency range, reducing its power in the actual frequency used by the equipment at any one time. The use of spread-spectrum techniques allow signals to be spread over a wide enough spectrum to make jamming of such a wideband signal difficult. The jamming in this case effectively becomes a beacon announcing the presence and location of the transmitter. This makes the use of such ECM a difficult decision – it may serve to obscure an exact location from non-ARMs, but in doing so it must put the jamming vehicle at risk of being targeted and hit by ARMs. Some modern fire-and-forget missiles like the Vympel R-77 and the AMRAAM use a combined approach, by using radar in the normal case, but switching to an antiradiation mode if the jamming is too powerful to allow them to find and track the target normally. This mode, called "home-on-jam", actually makes the missile's job easier, as the jammer usually puts out more power than normal radar return would. == See also ==