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Note: The topic of electronic warfare is vast and in many countries a closely guarded secret. Hence the data in this article is not always from open or fully verifiable sources. The topic as vast as this can also not be covered it its entirety in full also fro the reasons of space. This article mainly deals with general description of airborne EW from the Indian standpoint.
Introduction
The concept of Electronic warfare or EW is not new. It was practiced as early as the WW II albeit in a different way. The Germans used EW effectively to confuse British RADAR operators and quietly slipped two battle cruisers through the English Channel. Winston Churchill even called it the "Battle of the beams" and 'Wizard war". ECM (Electronic Counter Measures) and EW (Electronic Warfare) are today of the most important aspects of warfare. It’s importance in aircraft and pilot survival can never be under estimated. This article attempts to describe the equipment and the principles behind their application.
Radio silence, the earliest form of EMCON was practiced by the Japanese fleet during their attack on Pearl Harbour. Japanese carriers were ordered to maintain total radio silence until the final few moments before attack to take the Americans by surprise. Even more, the Japanese did not fly any patrols before the attack to decrease the likelihood of a radio message from a pilot in an emergency.
Examples for use of the EW in History
Interestingly enough, the electronic warfare is almost as old as the use of electronic for military purposes. At the time of the Russo-Japanese War, in 1904-1905, the Russian and Japanese fleets were well equipped with WT (wireless telegraph) sets. The Japanese navy used the WT freely and effectively to control the fleet, even though such transmissions often alerted the Russians to the presence of Japanese ships. The Russian Navy on the other hand tightly controlled its use of WT and exploited its passive and active modes tactically: a number of Russian ships avoided trouble when they heard Japanese signals traffic before they were spotted, and the Russians disrupted Japanese operations on several occasions by jamming their communications with WT.
During the WWI the electronic warfare was mainly limited to listening of enemy communications and sporadic jamming, but during the WWII the EW experienced rapid development, foremost as the most important parties involved started using radars. By 1944 the use of EW became widespread within the RAF's Bomber Command. The main purpose of different devices used was to confuse and dilute German defences, make large bombers inconspicious and make small aircraft look like large bombers, or make aircraft to appear as moving at very low speeds.
Immediately after the WWII, the development of the EW was slow, but it received an immense boast during the US engagement in SEA, and also due to appearance of large numbers of Soviet-built SAMs in the Middle East, where these were continuously confronting the Israeli Air Force during the "War of Atrittion", 1968-1970. Initially during these conflicts, the western systems were foremost used to identify the threat and advise the pilot to take neccessary steps to counter it. Subsequently their sophistication increased, and the simple systems were made capable of not only detecting the threat, but also countering it by electronic countermeasures.
Already at this time - during the early 1970s - it became common for every new radar to soon be followed by a system of appropriate electronic countemeasures (ECM), and in turn every ECM-system to be followed by the system of electronic counter-counter-measures (ECCM), that in turn was followed by the further development of the radar and the ECCM-systems so these can counter the ECM. Initially, such modifications were crude, and problematic to deploy, but today it is possible to modify any of the three components - radar, ECM, and the ECCM - in a matter of few hours. That is, unless a new threat incorporates some new kind of fundamental advance in technology.
In 1973, the SA-6 caused a considerable surprise for the Israelis - and the West in total - as at the time these had no ECM-system capable of effective countermeasures against the CW (continuous-wave) radars. The SA-6 initially caused heavy losses to the Israeli Air Force, and caused it either to avoid flying into certain areas, or to fly in a very specific manner - which then exposed the Israeli aircraft to other weapons, foremost MiG-21 interceptors and ZSU-23-4 radar-guided guns, that caused even more losses. This situation - as well as the heavy overclaiming of the number of Israeli aircraft shot down by Arab SAMs - caused such a shock in Israel and in the West, that most of the observers failed to observe the fact that already a more careful choice of tactics decreased the rate of losses to SA-6 almost to nil by the end of the first week of the war. In fact, subsequently the MiGs and ZSU-23-4s scored more kills against Israeli aircraft than the SA-6s.
But, the damage was already done, and the appearance of the SA-6 was a reason for a large number of important developments that were to follow, one of which was the deveopment of "low-observable" - or "stealth" - aircraft, while others were a fast series of new technologies developed in the arena of ECM and ECCM.
This development is characteristic for the "ping-pong" game the EW actually is, and which - for all practical purposes - is being continued right into our days. The only difference now is, that the electronic warfare today is less a matter of "East vs West" conflict, and far more the question of competittion between different companies from the defense sectors of different states.
What is EW?
Electronic warfare can be defined as any military action involving the use or manipulation of electromagnetic radiation to control the electromagnetic spectrum.
Electronic counter-measures (ECM) on the other hand are ways that the opposition tries to deny the use and advantage of the use of the electromagnetic spectrum. In simpler terms EW/ECM is a complex and technological game of ping-pong; with one side trying to outdo the other.
EW is a major facette in every area of a modern air warfare campaigns, including close air support (CAS), air-to-air, battlefield air interdiction (BAI), strikes against command and control targets, and destruction or suppression of enemy air defeces (DEAD and SEAD). Among all these, it is the last two that simply cannot succeed without ECM.
The objective of DEAD and SEAD is to destroy or suppress enemy air defence units and networks. SEAD is THE opening move employed by any capable air force initiating an air campaign in which the aircraft are to fly into enemy territory where essentially all enemy ‘eyes’ will be on them. Today there are two basic methods employed for this task: the deployment of stealth - or "low-observable" aircraft which are problematic to detect with the radar, or aircraft of conventional construction supported with specialized aircraft equipped for electronic warfare, preferrably supported with aircraft equipped with anti-radar missiles (ARMs).
Specialized EW-aircraft are often called "Wild Weasels", and their missions ‘Iron Hand’. They play a very vital role in jamming and disabling/destroying enemy RADAR positions (or just forcing them to shut down) while accompanying formations of strike aircraft. Probably the best known is the US-built Grumman EA-6B Prowler, currently the only dedicated EW-type in use; other air forces use modified standard airframes, like Tornado ECR (German and Italian Air Forces), MiG-23BN (in the Indian Air Force), and different Su-24-variants (Russian, Ukrainian, Algerian, and Iranian Air Forces), while one such dedicated type - the Grumman EF-111A (actually F-111A-airframes built by General Dynamics, and fitted with automatized versions of the same equipment carried by the EA-6B), was meanwhile taken out of service. The equipment of dedicated SEAD/DEAD aircraft is very expensive and extensive, and involves emission sensing pods, radar warning receivers (RWRs) or radar warning and homing systems (RHAWS), self-protection jammers (SPJ), automated countermeasures etc. These aircraft also carry specialized anti-radar missiles, like the ALARM, HARM, KH-31-P2, KH-25MP, ARMAT and others, which have sensitive seeker heads that can "lock on" to radiation emitting ground targets and home in on them.
The difference between SEAD and DEAD is that the SEAD operations manly sought to suppress enemy air defenses, foremost by causing them to shut-down their radars or risk destruction of these by ARMs. Th radar-operators could detect an ARM attack and would shut off their radars (and often turn the antennas the other way) to confuse and/or fool the incoming missile, causing it to miss. If successful, such tactics caused the radar would went off the air, but remain intact. Therefore the weapons needed for DEAD were developed, which has increased capabilities, in so far that now the ARMs memorize the position of the radars they are about to attack and ensure hitting the targeted radar antenna regardless if this is not emitting any more. Even more so, the SEAD aircraft are now teamed with other fighters, which strike enemy radars and SAM-stations with guided missiles and bombs, destroying them in the process.
Obviously, the side confronted with SEAD/DEAD tactics will start developing countermeasures, foremost by changing the way it uses its radars and other air defense systems. This, in turn, will cause changes in the way the SEAD/DEAD assets are deployed. Such ping-pong "games" are developing right since the WWII, with both sides trying to find ways how to counter each other. For example, the engineers found ways to home the missile even though the target RADAR had been switched off: they preprogrammed the missile to home into the RADAR's last known position. There are also SEAD/DEAD tactics even more ingenious discussed in the next topic.
RWRs and RHAWS
The RWR is one of the most basic fits on all modern aircraft and helicopters. It is basically a simplified ELINT device, passive by nature, and very small in weight, power, and drag effect on the aircraft carrying it. RWRs can vary greatly in sophistication and hence price. To have an all round coverage the aircraft must have receiver antennas mounted at different locations around the airframe to supply the RWR with signals. Each aerial is linked to a central processor through its own amplifier, which in turn is linked with the indicator in the cockpit. Most such indicators are relatively simple. A good example is the ARI.18223, used on RAF Jaguars and Harriers (Circa 1985), which has a circular display, with the lights turning showing the general direction of the threat.
Modern RWRs and RHAWs are designed to ignore all non-threat emissions (which are aplenty when the strike aircraft flies over hostile urban areas) and warn an aircraft only when a high Pulse Rate Frequency (PRF) has been established for a given period of time - which means that the enemy is well aware of the aircraft’s presence and has “locked on” to our aircraft.
A good example of a modern RWR is the AN/ALR-56M fitted to the F 15 Eagle, which can detect, self-classify and display the threat along with its distance and bearing to the pilot.
In order to be capable to show the threats, the RWRs must also be capable of recognizing them, and therefore they are constantly updated and upgraded. With an increased number of potential threats, and their sophistication, the RWRs were developed into RHAWs, which are far more complex systems that do not only give a clue about the side from which the potential threat is being faced, but also the types of the threat, the bearing to them and also show at the most dangerous. The RHAWs have usually a whole library of threats as well as sophisticated direction-finding equipment. They are usually also couppled with the - meanwhile largerly automatized - EW-suites of the aircraft, and enable them to react depending on the threat. In a consequence, the RHAWS are particularly expensive, and can today be found foremost on most modern tactical fighters and bombers.
Jamming, ECM-pods, and internal EW-installations
There are basically two types of ECM-installations on modern combat aircraft: internal and external. Certain services, like the USN, or the Russian Air Force, prefer to use internally mounted systems. Others - foremost the US Air Force, prefer external systems, the so-called ECM-pods. Due to USAF-influence, ECM-pods are extensively used in many air forces today, covering a variety of bands, including:
A = 250 MHz and below
B = 250-500 MHz
C = 500 - 1000 MHz
D = 1-2 GHz
E = 2-3 GHz
F = 3-4 GHz
G = 4-6 GHz
H = 6-8 GHz,
I = 8-10 GHz
J = 10-20 GHz
K = 20-40 GHz
L = 40-60 GHz.
The capability to cover several different "bands" is important, because different radars work in different "bands" of frequencies. The higher the number of the bands one pod can cover - especially if the installation can cover several bands simultaneously - the higher its capability will be. However, this must then be "mixed" with a sophisticated hardware and software, as well as emitting power. The "Noise", which is the least efficient - but best known - jamming mode tries to jam the enemy radar emitting signals on the same frequency as the radar, but which is stronger than that of the radar, thus "blotting" the radar returns out. This method is not as often used today as before, as installations on modern tactical fighters cannot even hope to match the radiated power of ground-based radars or those carried by AEW aircraft and helicopters, and AWACS.
"Transponder and repeater" jamming mode, which are triggered by the incoming hostile signal, and - though it is never quite possible to match the hostile frequency pulse for pulse - degrade the value of the enemy equipment by sending back a lot of closely related signals that will smother the return of the aircraft, or send back something that looks like a return from the aircraft but is not quite accurate.
Another frequently used jamming mode is the RGPO or range-gate stealing. This mode uses a transponder, which sends back a "reflected" pulse much larger in amplitude than the natural return of the aircraft. Such systems are automatic, i.e. they are triggered by enemy radar signals. The result of their work is that the enemy instead of seeing the return from the aircraft sees a large pulse which moves slowly away from the true position of the aircraft. Usually, the false position is astern of the aircraft, though, this must - of course - not always be the case. ECM-installations using these jamming modes are ideal for decepting radar-directed AAA, SAMs and AAMs and make them virtually harmless.
There are some jammers that have the "look through while jamming" capability. This is important in order for the jammer to continue to obtain signals from the receiver that is being jammed. Most often, this is done by stopping the jamming for brief periods of time for the receiver to "look through". The time that the jamming is stopped must be precise so that the look through receiver has enough time to record the jammed target and must also not be long enough to decrease jamming effectiveness.
As already indicated, there are two different types of ECM-installations: internal and the so-called ECM-pods. In contrast to internal installations, jamming pods are usually more effective in the sense that they can cover an arc of almost 360 degrees. They also do not require antennae and transmitters scabbed to the wingtips, tailfins, or elsewhere on the fuselage. On the flip side, however, externally-mounted pods are heavier, occupy a hard point under the fuselage and cause aerodynamic drag. It also happened often enough that powerful pods were causing problems to the avionics of the aircraft carrying them!
Nevertheless, the ECM-pods are usually modular in design, which makes them very easily upgradeable. This capability is important for multiple reasons, as the history of electronic wearfare showed that the means can swiftly chanbe. Consequently is there a constant need for simple and swift replacement of whole parts of EW-systems. This is where the ECM-pods excell: due to their modular system, they can be easily upgraded, their capability increased, reinforced, or specialized for a specific task.
A good example of an ECM-pod in widespread use is the US-built AN/ALQ-131 pod, carried by F-16s, C-130s, A-10s and some other types. The ALQ-130 is a compact but complex pod, consisting of receivers & transmitters which alter the path of missiles. The software of the pod is said to be altered/updated every two years or so. The pod is manually and automatically operated. It has sterling performance characteristics and is upgradeable. And still, in the USAF service it is being replaced by the Raytheon AN/ALQ 184 “Shadowbox” pod.
Far more powerfull and effective than such pods like ALQ-130 or ALQ-184 is the AN/ALQ-99. This installation, now exclusively carried by EA-6Bs (previously the ALQ-99 was also mounted on EA-6A and the EF-111A) is a combination of internal installation and external ECM-pods. The ALQ-99 is an extremely comprehensive tactical jammer, operating over a wide range of overlapping frequency bands. It is a complex and very effective system capable of processing a large amount of electronic emissions simultaneously. The ALQ-99 and associated sub-systems classify, prioritize, and initiate necessary jamming process of detected electronic emissions and can simultaneously cover five different bands. It is capable of operating in bands 1(VHF) to band 10. The Prowler can carry a maximum of five ALQ-99 pods - two under each wing and one under the fuselage (although, the more usual load-out are three), and has another "pod" mounted in the aerodynamical housing on the top of the fin. Each pod houses two powerful continuous wave (CW) transmitters which use beam steering to direct the jamming signal at the threat. The AN/ALQ-99 receivers and antennae are on board the aircraft in the tail cap, and the exciters and jamming transmitters are in pods under the wing. It also used to be carried on the Grumman EF-111A Raven where its emission-receiving system is carried on the tail fin. The ALQ 99 is invariably accompanied by Electronic countermeasures dispenser, radar countermeasures dispensers, self-protection and terminal threat warning systems.
Soviet Jammers
Very little open information is available about the status of Russian jammers. The main difference is that the designation system of exSoviet and Russian jammers is unlike their American counterparts: it is not following any alpha-numeric order, even if some of the designations tend to indicate this being the case. The other difference was, that the Soviets also preferred internal ECM-systems to ECM-pods, but that in some cases they developed podded-versions of their internal systesm.
Probably the most widespread exSoviet/Russian ECM-system is the basic SPS-141M; this was a jammer covering a single band, and usually used as a part of the SM-1 system, whose primary goal was to jam the venerable Nike Hercules and the MIM-23 Hawk SAM systems. The SM-1 and the SPS-141 combination are used on MiG-23 and MiG-25RB. The SM-1 system for the Sukhoi Su-17s and the Su-25s are already equipped with the SPS-141MVG jammers, which was also produced for export as SPS-141MVG-E, and as such acquired also by the Indian Air Force, probably for use on MiG-21s. The SPS-141MVG operates in 2 frequency bands.
One of the best-known modern Russian ECM-systems is the Gardeniya, usually used by Su-27s, but meanwhile also known to be in use on MiG-29s, as well as specialized Mi-17s, where it is also connected with chaff&flare dispensers.
The Tu-22M3 bomber has got the Miass EW suite, of which little is known. The PVO and the VVS also operated many specialized EW aircraft like the Yak-28 and the Tu-22P. The Yak carried the SPS-5-2X Fasol airborne search radar jammer, that was later used on the Su-24MP and Tu-22P EW-support aircraft. The SPS-22-2X Airborne radar jammer is also part of the Buket semi-automatic jamming suite fitted to the Yak-28PP.
The Soviets - and now the Russians - have also developed airborne infrared jammers, such like L166BIA, for use on their Mi-8MT/Mi-17, Mi-24, and Mi-25 helicopters. The L166BlA comprises a 365 x 463-mm transmitter-radiator unit which weighs ~20 kg and a 95 x 70 x 45-mm, relatively light cockpit control box. The L166BIA is quoted as offering protection against a range of threat missiles such as the Sidewinder, IR Falcon, and Mica, Strela 2M, Redeye and Chaparral.
French Jamming Pods
The French have started building ECM-pods already in the 1970s, but are developing internal suites only since the late 1980s. The Thomson CSF DB-3163 was the first of the French pods in service. It operated in only one band and later the DB evolved into the smaller Remora pod that the IAF operates, but with what sort of upgrades is still anybody’s guess. The Remora can jam in two bands.
The Barax, first seen in 1980 (l= 3.3 mts wt= ~80kg) was capable of covering two bands (two aerials). Another pod called Caiman is also in service. The Barracuda is the latest pod with at least two-band coverage.
Chinese EW
As is with the Chinese military, very little is known about advances made by the Chinese in this field. However it is well known that the II Persian Gulf war had a profound impact on Chinese thinking in this field of warfare. They soon undertook a massive upgrade and re-organization plan to develop and deploy ELINT and EW systems on various platforms including ships and military aircraft. Versions of the H-6 Bomber, Y-8 transport, and the J-8II fighter are known to have been developed to one degree or the other (the EJ-8 probably uses the KZ-900 pod). The PLAAF at present has at least two Tupolev Tu-154 EW-planes obtained with the help of the Russians. These aircraft are planned to be part of a national C3I system.
For the time being, however, the Chinese seems to be foremost interesting in collecting informations about the systems in use by the others.
Israeli EW-systems
Already during the early 1970s the Israelis started developing own versions of US-systems supplied to them. Today Israel is a one of the world-leaders on the topic of electronic warfare, and their defense sector is well-known for being capable of providing complete EWsolutions.
The Israeli-developed jammer pods and RWR s are in service with many countries worldwide, including India. One of the earliest pods developed/modified was the AN/ALQ 119(V)-17 pods which could supposedly jam even early model MiG-29s. This was followed by the ELTA 8202 used on the Kfir fighter.
The ELTA-8222 “Self Protection Pod” is a power-managed jammer, air-cooled system with an ESM receiver integrated into the pod, known meanwhile as being integrated in the MiG-21–93 project and also Jaguar/Shamsher fighter-bombers of the IAF. The pod contains an antenna on the forward and aft ends, which receive the hostile RF signal and after processing deliver the appropriate response. The EL 8240 is an example of a ram air-cooled, light (300 lbs), highly integrated system combining the RWR and the jammer fitting internally in an aircraft.
The EL/L 8247 is a highly compact and integrable RADAR Warning and Jamming System (RWJS), which can be integrated with a Missile Approach Warning System (MAWS) and a Laser Warning Receiver (LWR). Receiving frequencies range from
2-18 GHz and transmitting frequencies from 6.5 to 18 GHz.
The EL/L 8262 is a comprehensive EW suite which includes RWR, MAWS, LWR, EM jammer, chaff and flare dispensers and an EW central computer. The entire system can be controlled via a Multi Function Display (MFD).
Chaff and Flares
Chaff and flares are nowadays a common method of trying to evade an incoming missile or break a radar lock on. Chaff is mainly aluminum coated fiber glass (or Kevlar strip) slivers. Chaff was first used in WW II and is still used today. {During the Falklands war of 1982, RN Harriers did not have a ready set up for chaffs and used to carry the chaff jammed in between the airbrakes and stuffed between the pylons and bombs. The chaff was deployed by a rather rudimentary and stop-gap method of releasing the air-brake for a very short period of time whenever required.}
Flare cartridges like the Vympel fit on the MiG 21-93 are pyrotechnics used to fool the seeker head on Infra red-guided SAMs and AAMs.Flares are usually magnesium Teflon based. There are also Infra red jammers like the Russian Hot Brick jammer carried most probably on IAF MiG 27 MLs and Mi 24 Hinds. The infrared jammer can generate highly controlled high intensity bursts of energy which saturate the seeker, and confusing it, thus jamming the guidance of the incoming IR missiles.
Finally, for jamming laser-guided missiles, aerosols are used. It is known, for example, that the IAF deploys aerosol-dispersing devices as self-protection measure against the RBS-70 SAMs in Pakistani service.
Most of the chaff&flare dispensers today are mounted somewhere on the fuselage of different aircraft. Some, however, are mounted in separate pods. A good example for installations of this kind is the Swedish company Saab's BOP/B; a dispenser scabbed onto the rear of a weapons pylon that can release chaff, flares and expendable jammers.This system thus saves valuable space in the aircraft and also a pylon is freed up for more weapons or fuel.
Modern tactical fighters, especially those in the size- and weight-class as the Su-27/30, have their chaff&flare dispensers integrated with the RWR/RHAWS and the EW-systems, or the ECM-pods. Such complex systems are preferably power-managed and have an integrated ESM receiver. In ideal case, such fighters will carry also a missile-approach warning system (MAWS), as well as a Laser-Warning system, as well as a towed-decoy - so to be defended against all possible threads, and - of course - also have jam-proof communication suite.
High-value assets - foremost AWACS - are today foremost defended by the systems based on the concept of “smart jamming”e protection. It involves the oncoming missile being detected and classified presumably by identifying its seeker signature and then sending a jamming signal in a particular band to break its lock.
Anti-Radiation Missiles
The British ALARM (Air Launched Anti-Radiation Missile) is a good example of a modern-day ARM. It was used to success in the II Persian Gulf War, where the slightly modified PANAVIA Tornado GR.Mk.1s could carry upto 7 at a time. Upon launch, if the targeted radar was switched off, the ALARM would climb to ~40,000ft and descend slowly using a parachute, with the seeker head scanning to see if the targeted radar or any other target with similar emission characteristics has been switched on Once detected, the missile releases the parachute and flies toward the target.
Towed Decoys/Free Flying Decoys
Towed decoys are in concept similar to towed Torpedo decoys. The B-1B Lancer bomber and the F-16 figher, for instance, are known to have been equipped with ALE-50 and so does the F/A-18E/F. This system - sometimes referred to as “Little Buddy” - is said to have decoyed at least ten Serb SAMs from B-1B bombers. The ALE-50 was designed to protect the aricraft against radar-guided threats by luring an incoming missile away by presenting a more attractive target. It is the most rigorously tested decoy in USN/USAF history.
France has the SPECTRE system on its Mirage 2000-5. Others include Aerial, BO2D, Sky Buzzer, and AN/ALE 55.
Free flying decoys are on the other hand are released and not towed behind an aircraft they have the advantage of not being a drag inducing body in a high performance fighter aircraft. Also a self propelled decoy has a fairer chance of enticing away a missile than a towed decoy and no matter how good the decoy, if it is towed it presents a greater risk to the crew.
EW in the Indian Air Force
As is the nature with the Indian armed forces in general, the air force is very secretive about the use of Electronic Warfare in its ranks. The following is a tabulation based on the what little information is available.
The main RWR used is the Tranquil, an indigenous system, developed by the DRDO. It has direction finding capability and is known to have a programmalbe threat library. Tranquil is known to have been fitted on the MiG-21UPGs and a reworked and modified version will be fitted to the Su-30 MKI.
The Tempest is a jammer system capable of barrage-, continuous-wave-, and pulse-repeater jamming. It will be fitted to the MiG-21UPGs of the Indian Air Force.
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