Electronic Warfare

Authors 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 sources. The topic being so vast has not been covered in its entirety; it has not included land and ship based EW, as well as an analysis of Electronic Support Measures (ESM).
This topic mainly deals with airborne EW and that too not extensively with the Electronic INTelligence (ELINT).

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. Its 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.

WHAT IS ECM/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 are 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 ECM/EW is a complex and technological game of ping-pong; With one side trying to outdo the other.

Externally mounted and podded (sometimes internally fitted) jamming devices provide protection to aircraft against RADAR guided SAMs, RADAR guided Self Propelled guns etc.

Another major element in this aspect is the mission called Suppression of Enemy Air Defenses (SEAD). Aircraft sometimes called Wild Weasel aircraft fly these missions. They play a very vital role mainly in jamming and destroying enemy RADAR positions while accompanying formations of strike aircraft.
The equipment used on these modified aircraft (like the MiG 23BN, EA 6B,EF 111,Su 24 variants, Tornado ECR etc.) is very extensive and involves the use of Emission sensing pods, RADAR Warning Receivers (RWR), Self Protection Jammers (SPJ), automated countermeasures etc. These aircraft also carry specialized Air to Ground missiles like the ALARM, HARM, KH 31 P2, KH 25-MP, ARMAT etc which have sensitive seeker heads which "lock on" to Radiation emitting ground targets (with a targeting pod) and home in on the target.

There earlier were ways to evade ARMs. RADAR operators on detecting an ARM launch would shut off their RADARs to confuse and fool the incoming missile. However the ping pong game that ECM/EW is, Engineers soon found ways to target the missile even though the target RADAR had been switched off. The engineers had preprogrammed the missile to home into the RADAR's last known position and tactics even more ingenious discussed in the next topic.

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 Gulf War where the Tornado GR 1 could carry upto 7 at a time. The ALARM when launched and if the target RADAR is switched off climbs to ~40,000 feet and descends slowly using a parachute scanning to see if any RADAR has been switched on. Once detected, the missile releases the parachute towards the target.

RADAR WARNING RECIEVERS

A Radar Warning Receiver is one of the most basic fits on aircraft and helicopters. It is basically an ELINT device. It is a passive device and only has a very small weight, power, ands drag effect on the aircraft carrying it. RWR s can vary greatly in sophistication and hence price. To have an all round coverage the aircraft must have antennae at different locations to supply the RWR with signals. Each aerial is linked to a central processor through its own amplifier. The ARI.18223 used on RAF Jaguars and Harriers (Circa 1985) only lights up the part of a circular display to give the general direction of the threat. Most modern RWR s have a library of known threats, as well as direction finding equipment.

Modern RWR s are designed to ignore all non threat emissions (which are aplenty when a 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 this means that the enemy is well aware of the aircrafts presence and has locked on to our aircraft.

A good example of a modern RWR is the AN/ALR 56 M fitted to the F 15 Eagle which can detect, self classify and display the threat along with its distance and bearing to the pilot.

JAMMING PODS AND ECM PODS

Jamming and ECM pods are extensively used in many air forces today, covering a variety of bands (A = 250 MHz and below and B = 250-500 MHz, C = 500 - 1000 MHz,
D = 1-2 GHz and E = 2-3 GHz and F = 3-4 GHz and G = 4-6 GHz and H = 6-8 GHz,
I = 8-10 GHz and J = 10-20 GHz and K = 20-40 GHz and L = 40-60 GHz). They form the most basic past of a SEAD aircraft's SAM suppression ability. Jamming pods are in contrast with internal ECM more effective in the sense that they can cover an arc of almost 360 degrees. They also donot require antennae and transmitters scabbed to the wingtips, tailfins, on the belly etc. Also internal ECM does not have the kind of coverage of a belly-mounted pod.
However on the flip side, external mounted pods are heavier, occupy a hard point under the fuselage and are in most cases not aerodynamic. Sometimes it has also been noted that powerful pods like the AN/ALQ-131 caused problems to the aircraft carrying them! Jammers are also modular in design thus making them easily upgradeable.
There are some jammers that can "look through" while jamming capability. It is important in order that the jammer continue to obtain signals from the receiver that is being jammed. This is most often 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 receiver and must also not be long enough to decrease jamming effectiveness.

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, 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 mode, but best known, 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. However this method is not always useful the fighter cannot even hope to match the radiated power of a giant ground based RADAR.

"Transponder and repeater" 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.

The last mode used is namely, 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 "our" 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 our aircraft sees a large pulse
Which moves slowly away from our true position. Usually, the false position is astern of the aircraft, though, this must - of course - not always be the case. Such ECM pods are ideal for decepting radar-directed AAA, SAMs and AAMs and make them virtually harmless.

THE AN/ALQ-131

The AN/ALQ-131 is widely used on various US made aircraft like the A 10,F 16,F 15,F 4,C 130 etc.
It is a compact and complex pod consisting of receivers & transmitters which alter the path of missiles. The pods software 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.
However this pod is being replaced by the Raytheon An/ALQ 184 Shadowbox jammer.

THE AN/ALQ 99

The AN/ALQ 99 extremely comprehensive tactical jammer, operating over a wide range of overlapping frequency bands, used on arguably the world's best ECM platform the EA 6B Prowler aircraft. It is a complex and very effective system capable of processing a large amount of RADAR signals and jamming different RADAR threats. The RADAR emissions detected are classified, prioritized and the necessary jamming process is initiated.
It is capable of operating in bands 1(VHF) to band 10.
The Prowler carries five ALQ-99 pods, two under each wing and one under the fuselage. 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 antennas are on board the aircraft in the tail cap, and the exciters and jamming transmitters are in pods under the wings.
It can also be carried on the EF 111 Raven where it's 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.

CHAFF AND FLARES

Chaff and flares are nowadays a common method of trying to evade an incoming missile or break a RADAR lock.
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 also exist 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, confusing it thus jamming the guidance of the incoming IR missiles.

SOVIET JAMMERS

Very little open information is available about the status of Russian jammers; there are however many like the SPS 141 etc. The designation of Russian jammers is unlike their American counterparts is not in any numeric order. The basic SPS 141 M was a jammer covering a single band and 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 combo were used on MiG 23 and MiG 25 RB.
The SM 1 system for the Su 17 Fitter and the Su 25 Frogfoot incorporate the use of the SPS 141 MVG jammer, the export version of which the SPS 141 MVG-E was acquired by the IAF to presumably fit the MiG 21.The SPS 141 MVG operates in 2 frequency bands.

FRENCH JAMMING PODS

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 IAF operates, but with what sort of upgrades is still anybodys 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 the 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 as the case with many other countries, the Gulf war of 1991-92 had a great impact on Chinese thinking in this field of warfare. They soon began 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 H6 Bomber, Y8 transport and J8 II (The E J 8 probably uses the KZ 900 pod.. unfortunately not much data is available) aircraft are used to name a few. The PLAAF at present has at least 2 Tupolev Tu 154 EW planes obtained with the "help" of the Russians. These planes are planned to be par of a national class C3I system. With a view of strengthening its ELINT assets the PLAAF has recently developed a HF reconnaissance system. This system is used to monitor enemy radio traffic during wartime. It can also supposedly record these HF signals. This system is said to be able to keep track of almost 500 targets and takes up the size of a small room.
China seems to have made advancements in leaps and bounds in collecting electronic information

ISRAELI EW

Israel is a one of the world leaders today in the field of providing complete EW solutions for the worlds militaries. 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 with an ESM receiver integrated into the pod. It is reportedly being used on MiG 21 93 fighters and Jaguar aircraft of the IAF and IN respectively. It is cooled by ram air. Thje pod contains antennae on the forward and aft parts of the pod 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).

ADVANCES IN EW TECHNOLOGY

TOWED DECOYS/ FREE FLYING DECOYS

Towed decoys are in concept similar to towed Torpedo decoys. The B 1B Lancer bomber, the F 16, for instance tows the ALE 50 and so does the soon-to-be-inducted F/A 18 E/F. The Little Buddy is said to have decoyed at least 10 Serb SAM s from B 1B bombers. It lures away an incoming missile by presenting a more attractive target.
The system is designed to protect the aircraft against RADAR guided threats. It is the most rigorously tested decoy in USN/USAF history.
France has the SPECTRE towed decoys on its Mirage 2000-5. Others include Aerial, BO2D, Sky Buzzer, 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.

The concept of Smart Jamming is being considered for the protection of high value and lumbering targets like the C 130, C 5 and AWACS. 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.

Missile Approach Warning System (MAWS) is a system designed to protect aircraft by warning him of an incoming missile.

PYLON MOUNTED DISPENSERS

Swedish company Saab has developed the BOP/B; a dispenser scabbed onto the rear of a weapons pylon that can release chaff, flares and expendable jammers.

AN EW EQUIPPED FIGHTER AND ITS COMPONENTS

A fighter in the same weight class as the Su 27/30 would have basically enough rounds of chaff and flare dispensers integrated with the RADAR Warning Receiver (RWR) and the EW system onboard. The fighter would also carry with it a under slung jammer pod, preferably power managed and having an integrated ESM receiver in it. The fighter would also carry a MAWS system and a Laser Warning system to boot all tied in to a central EW computer. All communications would be jam proof. All these would almost build a protective bubble around the fighter.

ECM PODS IN USE TA A GLANCE

COUNTRY: NAME: AIRCRAFT TYPE:

SWEDEN U 22/A A/JS Viggen

AXEL J/A 37

G 24

USA AN/ALQ-126 B F/A 18,F 14,EA 6 B

AN/ALQ 165 F 14 D

AN/ALQ 164 Av 8 B

AN/ALQ 167 F 14 D

AN/ALQ 135 bands1,2mod &3 F 15 C

AN/ALQ 135D(v) F 15 E

AN/ALQ 134/A84 POD

AN/ALQ 161 B 1B

AN/ALQ 131 C 130,F 16 A-D,A 10

FRANCE Thomson CSF DB 3163 Mirage F1

REMORA Mirage 2000,Mirage F1

BARAX Mirage 2000

BARRACUDA

CAIMAN Mirage 2000

RUSSIA SPS 130
SPS 140
SPS 141
SPS 142
SPS 150
SPS 160
SPS 161 Su 22 M4-K
SPS 170
L175V/KS418 Su 32
L005S Sorbtsya Su 27

OTHERS ELT-555 Amx
EL/73
ZEUS
ARI 23246
BOZ 100/103
SATT AQ 31
CEREBRUS III

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