Page 172 - Radar Technology Encyclopedia

ELECTRONIC INTELLIGENCE (ELINT) ELECTRONIC WARFARE 162

radar modifications and new radar capability. In addition, the tage, as it ensures the security of operation and permits to
electronic order-of-battle, if kept current, can be used to detect the sources of radiation at ranges greater than even the
ensure that the appropriate sets of ECM equipment are avail- range of intercepted sensors (radars, lasers, etc.). The disad-
able and deployed as the situation requires. Such knowledge vantage of the passive mode is that the range to the source of
can often mean the difference between success and failure radiation must be generally obtained using multiple ESM
when air attacks against the radar air-defense systems are fixes on the target (for example, by means of triangulation).
contemplated. PCH To accomplish the comprehensive analysis of the intercepted
Ref.: Schleher (1986); Wiley (1982). sources including detecting, locating, classifying, and identi-
fying the sensors, ESM system must have a threat library rep-
ELECTRONIC INTERFERENCE (see INTERFER-
resenting the main features of the enemy’s electronic order-
ENCE).
of-battle stored in its microprocessor. The main ways to
ELECTRONIC JAMMERS (see JAMMER). reduce the efficiency of ESM is to decrease the time when the
active sensor that may be intercepted by this system is turned
ELECTRONIC JAMMING (see JAMMING). on to minimize warning time, and to use when possible com-
pletely passive weapons, such as antiradiation missiles and
ELECTRONIC RECONNAISSANCE (see ELEC-
heat-seeking missiles. Typically, the ESM subsystem and
TRONIC SUPPORT MEASURES).
ECM subsystem are the integrated parts of the same EW sys-
ELECTRONIC SIGHT (see SIGHT). tem, and the link between them is often automatic. SAL
Ref.: IEEE (1990), p. 16; Barton (1991), p. 12-2; Skolnik (1990), p. 9.2;
ELECTRONIC (WARFARE) SUPPORT MEASURES
Schleher (1986), p. 6; Neri (1991), p. 279.
(ESM) are “actions taken to search for, intercept, locate,
record, and analyze radiated electromagnetic energy for the ELECTRONIC WARFARE (EW) is “a military action
purpose of exploiting such radiations in support of military involving the use of electromagnetic energy to determine,
operations.” The main difference between ESM and signal exploit, reduce, or prevent hostile use of the electromagnetic
intelligence is that the first requires immediate actions while spectrum and action while retains friendly use of the electro-
the latter gathers the intelligence information which can be magnetic spectrum.” EW is divided into three classic catego-
processed later. The major constituent parts of ESM systems ries: electronic (warfare) support measures (ESM), electronic
are radar warning receivers and appropriate antennas. Typi- countermeasures (ECM), and electronic counter-countermea-
cally, an ESM system is completely passive and it locates the sures (ECCM). The structural tree depicting basic EW areas
sources of electromagnetic energy (e.g., radars) only in angle is shown in Fig. E6.
by measuring the angle of arrival. It is an important advan-

Figure E6 Electronic warfare areas (from Schleher, 1986, Fig. 1.1, p. 7).