Electronic countermeasure
An electronic countermeasure (ECM) is an electrical or electronic device designed to trick or deceive radar, sonar, or other detection systems, like infrared (IR) or lasers. It may be used offensively and defensively to deny targeting information to an enemy. The system may make many separate targets appear to the enemy or make the real target appear to disappear or move about randomly. It is used effectively to protect aircraft from guided missiles. Most air forces use ECM to protect their aircraft from attack. It has also been deployed by military ships and recently on some advanced tanks to fool laser/IR-guided missiles. It is frequently coupled with stealth advances, so the ECM systems have an easier job. Offensive ECM often takes the form of jamming. Self-protecting (defensive) ECM includes blip enhancement and jamming missile terminal homers [Pucker, p. 23].
The first example of electronic countermeasures applied in a combat situation occurred during the Russo-Japanese war. On July 13, 1904, Russian wireless telegraphy stations installed in the Port Arthur fortress and onboard Russian light cruisers successfully interrupted wireless communication between Japanese battleships. The spark-gap transmitters in the Russian stations generated senseless noise while the Japanese were making attempts to coordinate their efforts in the bombing of a Russian naval base. Germany and the United Kingdom interfered with enemy communications along the western front during World War I. At the same time, the Royal Navy tried to intercept German naval radio transmissions [Polmar, p. 121]
Polmar, N. (1979). The U. S. Navy Electronic Warfare (Part 2). Annapolis: United States Naval Institute Proceedings.
Pucker, L. (2009). Electronic Counter Measures. Spectrum: Signal Processing. Victoria: Vecima Networks.