Editing Signals intelligence (section)

==Electronic signals intelligence==
Electronic signals intelligence (ELINT) refers to [[list of intelligence gathering disciplines|intelligence-gathering]] by use of electronic sensors. Its primary focus lies on [[non-communications signals]] intelligence. The Joint Chiefs of Staff define it as "Technical and geolocation intelligence derived from foreign noncommunications electromagnetic radiations emanating from sources other than nuclear detonations or radioactive sources."<ref name =JP1-02 />

Signal identification is performed by analyzing the collected parameters of a specific signal, and either matching it to known criteria, or recording it as a possible new emitter. ELINT data are usually highly classified, and are protected as such.

The data gathered are typically pertinent to the electronics of an opponent's defense network, especially the electronic parts such as [[radar]]s, [[surface-to-air missile]] systems, aircraft, etc. ELINT can be used to detect ships and aircraft by their radar and other electromagnetic radiation; commanders have to make choices between not using radar ([[EMCON]]), intermittently using it, or using it and expecting to avoid defenses. ELINT can be collected from ground stations near the opponent's territory, ships off their coast, aircraft near or in their airspace, or by satellite.

===Complementary relationship to COMINT===
Combining other sources of information and ELINT allows traffic analysis to be performed on electronic emissions which contain human encoded messages. The method of analysis differs from SIGINT in that any human encoded message which is in the electronic transmission is not analyzed during ELINT. What is of interest is the type of electronic transmission and its location. For example, during the [[Battle of the Atlantic]] in [[World War II]], [[Ultra (cryptography)|Ultra]] COMINT was not always available because [[Bletchley Park]] was not always able to read the [[U-boat]] [[Enigma machine|Enigma]] traffic. But [[high-frequency direction finding]] ("huff-duff") was still able to detect U-boats by analysis of radio transmissions and the positions through triangulation from the direction located by two or more huff-duff systems. The [[Admiralty (United Kingdom)|Admiralty]] was able to use this information to plot courses which took convoys away from high concentrations of U-boats.

Other ELINT disciplines include intercepting and analyzing enemy weapons control signals, or the [[identification, friend or foe]] responses from transponders in aircraft used to distinguish enemy craft from friendly ones.

===Role in air warfare===
A very common area of ELINT is intercepting radars and learning their locations and operating procedures. Attacking forces may be able to avoid the coverage of certain radars, or, knowing their characteristics, [[electronic warfare]] units may jam radars or send them deceptive signals. Confusing a radar electronically is called a "soft kill", but military units will also send specialized missiles at radars, or bomb them, to get a "hard kill". Some modern air-to-air missiles also have radar homing guidance systems, particularly for use against large airborne radars.

Knowing where each surface-to-air missile and [[anti-aircraft artillery]] system is and its type means that air raids can be plotted to avoid the most heavily defended areas and to fly on a flight profile which will give the aircraft the best chance of evading ground fire and fighter patrols. It also allows for the [[Radar jamming and deception|jamming]] or [[Spoofing attack|spoofing]] of the enemy's defense network (see [[electronic warfare]]). Good electronic intelligence can be very important to stealth operations; [[stealth aircraft]] are not totally undetectable and need to know which areas to avoid. Similarly, conventional aircraft need to know where fixed or semi-mobile [[anti-aircraft|air defense]] systems are so that they can shut them down or fly around them.

{{anchor|ELINT and ESM|ESM|Electronic Surveillance|Electronic Surveillance Measures|Electronic Surveillance System}}

===ELINT and ESM===
'''Electronic support measures (ESM)''' or '''electronic surveillance measures''' are ELINT techniques using various ''electronic surveillance systems'', but the term is used in the specific context of tactical warfare. ESM give the information needed for '''electronic attack (EA)''' such as jamming, or directional bearings (compass angle) to a target in ''signals intercept'' such as in the [[High-frequency direction finding|huff-duff]] radio direction finding (RDF) systems so critically important during the World War II [[Battle of the Atlantic]]. After WWII, the RDF, originally applied only in communications, was broadened into systems to also take in ELINT from radar bandwidths and lower frequency communications systems, giving birth to a family of NATO ESM systems, such as the shipboard US [[AN/WLR-1]]<ref 
name="WLR-1">{{cite web|url=https://fas.org/man/dod-101/sys/ship/weaps/an-wlr-1.htm|title=AN/WLR-1|date=1999-01-01|access-date=2015-09-27}}</ref>—[[AN/SLQ-32 Electronic Warfare Suite|AN/WLR-6]] systems and comparable airborne units. EA is also called '''electronic counter-measures (ECM)'''. ESM provides information needed for '''electronic counter-counter measures (ECCM)''', such as understanding a spoofing or jamming mode so one can change one's radar characteristics to avoid them.

===ELINT for meaconing===
[[Meaconing]]<ref>{{cite web|last=US Army|author-link=US Army|title=Chapter 4: Meaconing, Intrusion, Jamming, and Interference Reporting|work=Field Manual 23–33, Communications Techniques: Electronic Counter-Countermeasures|date=17 July 1990|url=https://fas.org/irp/doddir/army/fm24-33/fm243_5.htm|id=FM 23–33|access-date=1 October 2007}}</ref> is the combined intelligence and electronic warfare of learning the characteristics of enemy navigation aids, such as radio beacons, and retransmitting them with incorrect information.

===Foreign instrumentation signals intelligence===
{{Main|Foreign instrumentation signals intelligence}}
FISINT ([[Foreign instrumentation signals intelligence]]) is a sub-category of SIGINT, monitoring primarily non-human communication. Foreign instrumentation signals include (but not limited to) [[telemetry]] (TELINT), tracking systems, and video data links. TELINT is an important part of [[national means of technical verification]] for arms control.

===Counter-ELINT===
Still at the research level are techniques that can only be described as [[MASINT#Research programs: Smart Dust and WolfPack|counter-ELINT]], which would be part of a [[SEAD]] campaign. It may be informative to compare and contrast counter-ELINT with [[Electronic counter-countermeasures|ECCM]].