Page 173 - Radar Technology Encyclopedia

163 ELECTRONIC WARFARE EQUIVALENCE PRINCIPLE

In a broad sense EW typically incorporates the following ware usually referred to as hybrid simulators. SAL
constituent parts: electronic (warfare) support measures, sig- Ref.: Schleher (1986), p. 19.
nal intelligence, signal security, electronic countermeasures,
EW support measures (see ELECTRONIC SUPPORT
electronic counter-countermeasures, defence suppression, and
MEASURES).
electronic warfare simulators. SAL
Ref.: Schleher (1986). ENCODER, shaft angle (see CONVERTER, angle- to-
code).
EW intelligence refers primarily to measures used to gain
information on potential targets for ECM activities. Security ELEVATION (see ANGLE, elevation).
measures such as radio or radar silence and encryption,
intended to deny a potential enemy the opportunity to inter- ENVELOPE (see DETECTOR, amplitude).
cept one’s own signals, are sometimes included in the defini-
EQUALIZATION is the process of removing amplitude and
tion of EW intelligence.
phase distortions in radar channels (amplitude equalization
EW intelligence can be either tactical or strategic in
and phase equalization correspondingly). Typically, in hard-
nature. Tactical use of EW intelligence generally comes under
ware, the process of equalization is implemented by means of
the heading of electronic support measures (ESM), and refers
equalization filters which are designed by synthesizing an
to real-time collection and analysis of electronic intelligence
auxiliary transfer functions to produce flat amplitude and lin-
(ELINT) for the purpose of updating an electronic order-of-
ear phase transfer characteristics. The transversal filter is
battle (EOB) and for selecting ECM responses to a battlefield
widely used in the equalization of amplitude-phase distor-
deployment of air-defense systems. Such information may be
tions. An example of equalizing transversal filter based on
augmented by communications intelligence (COMINT) data,
wideband, dispersion-free, IF, tapped-delay-line used in pulse
derived from intercepts of radio transmissions that may reveal
compression radar is shown in Fig.E7.
tactical intent on the part of an enemy and battlefield deploy-
The necessity of equalization is especially acute in wide-
ments. Tactical combat aircraft are generally equipped with
band radars. SAL
passive ESM equipment interfaced with active ECM systems
Ref.: Skolnik (1990), p. 10.36; Wehner (1987), p. 59.
for automatic response to threatening air-defense systems.
ELINT and COMINT are subsets of the more general cate-
gory of signals intelligence (SIGINT).
SIGINT can be a major sources of strategic intelligence
that provides not only an up-to-date EOB, but technical data
that may reveal important information about specific radar
and radar weapon system capabilities.
Other categories of EW intelligence include operations
intelligence (OPINT), which are nonelectronic means of col-
lecting information that may reveal operational procedures, or
tactical movement of enemy forces on the battlefield, and
radiation intelligence (RINT), which is different than ELINT
in that RINT relies on the interception of spurious and unin-
tended radiation to derive information relative to the presence
and characteristics of hostile electronic systems, including
radar and EW systems.
Measures taken to deny an enemy knowledge of one’s
own presence and electronic systems capabilities include
emission control (EMCON), an operational state in which no Figure E7 Transversal equalizer for reduction of time sidelobes
radiation is permitted (radar and radio silence), use of data (from Skolnik, 1990, p. 10.36, reprinted by permission of
encryption, and employment of low probability of intercept McGraw-Hill).
(LPI) radar or radio systems. PCH
EQUIVALENCE PRINCIPLE. The equivalence principle
Ref.: Schleher (1986), pp. 6–9.
is the principle based on the assumption that radiation of
Electronic warfare simulators are the simulators used for antenna computed from the electric and magnetic current
training of EW operators in a realistic combat environment, sheets on the closed surface so that the fields inside a closed
test and evaluation. The main purpose of EW simulators is to surface are zero and supposing that a given distribution of
present EW data as would be encountered in an operating sit- electric and magnetic fields was substituted by appropriate
uation and simulate realistic threat scenarios common to distribution of electric and magnetic current sheets is identi-
modern EW environment. The basic types of these simulators cal (except for a difference in sign) to the radiation that would
involve the usage of pure hardware signal radiators, pure have been produced by the original sources inside the closed
computer simulation, and combination of hardware and soft- surface drawn about the antenna structure. The principle was