Electronic Countermeasures

Electronic Countermeasures 

(ECM), measures taken to deliberately disrupt the normal operation of radioelectronic equipment for military purposes by using electronic techniques. ECM is used to protect aircraft, including airplanes, guided and ballistic missiles, and helicopters, surface ships, submarines, and ground targets from enemy detection by electronic devices and from destruction by radio-controlled missiles or other weapons. Such measures are also used to disrupt other enemy activities involving the use of radio equipment, for example, to jam radio communications. ECM includes actions taken against the operation of radio and radar equipment (radio ECM), infrared equipment (infrared ECM), and optical-electronic equipment, including lasers.

Radio ECM directed against the operation of radar stations, remote-control and data-transmission radio lines, radio-navigation devices, and radio-communications devices is accomplished by creating deliberate radio interference, changing the characteristics of signals reflected by objects, forming dummy targets, and using missiles that home in on targets that emit radio waves. Deliberate radio interference is one of the most common and effective radio-ECM techniques, particularly in countering the normal operation of radar equipment (see). Changes in the characteristics of reflected signals are achieved by reducing the intensity of reflection of radio waves or by distorting the structure of the radio waves when they are scattered by targets. Such changes of echo signals may also be achieved by using special coatings that absorb radio radiation, artificially changing the configuration of objects to camouflage distinctive features, or altering the propagating medium of radio waves, for example, by changing the properties of the plasma layer surrounding a ballistic missile.

Dummy targets are used to overload electronic systems that process data and sort targets, or they may be used to jam the reception of information on the attitude and movements of the target. This makes it difficult or impossible to launch a missile against the true target, or it can divert guided missiles or other means of destruction away from targets. Dummy targets are equipped with radio-wave reflectors or radio-interference transmitters; they include towed or self-propelled dummy missiles used in the protection of aircraft, and dummy targets located in the final stage of a missile or dummy warheads that separate from a launch vehicle used in the protection of ballistic-missile warheads. Radio equipment can be destroyed or damaged by missiles that home in on the radio waves emitted by the equipment.

ECM techniques employed against devices operating in the optical band are basically the same as those used in radio ECM. Infrared countermeasures primarily involve the use of dummy targets and camouflage. The dummy targets create artificial infrared radiation and divert enemy devices used for detection and weapons guidance from the true targets. Infrared camouflage reduces the heat contrast between the camouflaged objects and the surrounding environment. This is done by reducing the intensity of infrared radiation emitted by the camouflaged objects using special shields, heat-insulating coatings, and aerosol curtains, such as smoke, that absorb infrared radiation. For military weapons and equipment operating in the visible part of the optical band (for example, aerial bombs equipped with laser and television guidance, laser range finders, and lidar), ECM techniques are being developed that are similar to those used in radio and infrared ECM.

REFERENCES

Vakin, S. A., and L. N. Shustov. Osnovy radioprotivodeistviia i radiotekhnicheskoi razvedki. Moscow, 1968.
Kriksunov, L. Z., and I. F. Usol’tsev. Infrakrasnye sistemy obnaruzheniia, pelengatsii i avtomaticheskogo soprovozhdeniia dvizhushchikhsia ob”ektov. Moscow, 1968.
Petrovskii, V. I., and O. A. Pozhidaev. Lokatory na lazerakh. Moscow, 1969.
Radiotekhnicheskie sistemy v raketnoi tekhnike. Moscow, 1974.
Palii, A. I. Radioelektronnaia bor’ba. Moscow, 1974.

B. D. SERGIEVSKII