ELINT
Electronic Intelligence — the SIGINT sub-discipline covering non-communications electronic signals, principally radar
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ELINT — electronic intelligence — is the SIGINT sub-discipline covering non-communications electronic signals. The standard US doctrinal definition (Joint Publication 2-0; the historical National Reconnaissance Office and Defense Intelligence Agency definitions) is intelligence derived from the technical and parametric characteristics of foreign electronic emitters that do not carry communications traffic — principally radar systems, navigation aids, identification-friend-or-foe (IFF) systems, fire-control radars, and the broader emitter infrastructure of foreign air defence, naval surveillance, and ground-based weapons systems.
The discipline divides operationally into two principal components. Technical ELINT (TechELINT) characterises the electronic parameters of emitters — the frequency, pulse repetition interval, scan pattern, modulation, and other technical signatures that uniquely identify a particular radar or emitter type and (often) a particular individual emitter installation. Operational ELINT (OpELINT) characterises the deployment, operational status, and operational behaviour of those emitters — where they are located, when they radiate, what their tracked targets are, and how they are integrated with other emitters into an air-defence or weapons-employment network.
The institutional history of US ELINT runs through the Air Force, Navy, and National Security Agency cryptologic components, the National Reconnaissance Office's airborne and space-based ELINT collection systems, and (from 1961) the Defense Intelligence Agency's analytical production. The principal documented Cold War ELINT systems include the U-2 reconnaissance aircraft's signals-collection variants, the RC-135 fleet of dedicated SIGINT aircraft (in service in successive variants from the 1960s to the present), and the long sequence of dedicated ELINT satellites (Canyon, Rhyolite, Aquacade, Magnum, Mercury, Mentor, Orion in successive generations) operated by the National Reconnaissance Office.
ELINT's relationship to MASINT is sometimes contested. The technical signature analysis of foreign emitters — the discrimination between specific radar types, the identification of specific weapons-system fire-control associations — sits at the boundary between the two disciplines. The convention that has emerged in US doctrine is that ELINT covers the radio-frequency electronic emitter signatures themselves and MASINT covers the broader category of physical-phenomenon signatures (acoustic, seismic, nuclear, optical, infrared, magnetic, chemical, biological), with the working overlap at radio-frequency MASINT handled case-by-case.
The principal operational consumers of ELINT have historically been the air-defence-suppression and electronic-warfare communities, where the parametric and locational data are required for the targeting and deception of foreign emitters during military operations, and the strategic-warning community, where changes in foreign air-defence and missile-system emitter activity have historically been a principal indicator of impending action. The post-2001 expansion of unmanned aerial systems and the continuing post-2014 evolution of foreign integrated air-defence systems have kept ELINT a substantial and operationally consequential sub-discipline.