With Waveforms and Wits

June 1, 1987

In the world of electronic combat, skill and cunning are frequently as important as superior weapons and systems. The principle is illus­trated by the task assigned to Wild Weasel aircrews flying SAM sup­pression for Operation Linebacker II in December 1972.

The United States, seeking a con­clusion to the Vietnam War, sent its heavy bombers and everything else it could lay hands on to pound Hanoi and Haiphong relentlessly for eleven days. Hanoi itself was protected by the most lethal de­fenses in North Vietnam, including a cordon of SA-2 surface-to-air mis­siles deployed on all approaches to the city.

Suppressing the radar-controlled SA-2s was the job of the Wild Weasels, organized for that very purpose in the early part of the war. There weren’t many of the Wild Weasels, though, and with attacks continuing around the clock, only a few Weasels at a time could be over Hanoi to support the typical Line­backer II bomb run.

“If anybody had told me in pilot training that I’d be going to down­town Hanoi at night with only two bullets [Shrike antiradiation mis­siles] to cover five SAM sites for twenty minutes, I’d probably have turned in my wings right then,” says Tom Floyd, a Weasel pilot who was there. “But we did it.”

Sometimes they did it by straight­forward assault on the SAM sites, at other times with distraction, intim­idation, and maneuvering. The basic idea was to neutralize a part of the SAM defenses long enough for the bombers to get through and de­liver their ordnance. Sometimes the SAMs won the engagement, and sometimes the Weasels did.

Vietnam was the war in which electronic combat came of age. It introduced the use of surface missile defenses linked to target-track­ing radars to shoot down penetrat­ing aircraft. This war also saw large numbers of US fighters go into bat­tle with ECM (electronic counter­measures) pods slung under their wings to help them avoid engage­ments. B-66 bombers were given an E prefix and adapted to jam North Vietnamese communications and radars. And in 1965, the Wild Weasels were invented to stalk and fight the SAMs with lethal elec­tronics of their own.

Col. Sam Peacock, a former Weasel now working in the Pen­tagon, says that merely going into sequence for a Shrike launch was often enough to intimidate SAM batteries, making them shut off their radars. If the battery did fire, the Weasel might duck behind a hill to break the radar’s lock or “take it down” in the classic Weasel maneu­ver—an afterburner dive with a hard turn at the bottom that the mis­sile couldn’t follow.

Skill and cunning work both ways, of course. The SAM radar emitted a telltale signal when launch was imminent. The Weasels were alert for it. Consequently, the SAM operators learned to put up phony signals to fake the Weasels. They also surprised them by firing the missile in the general direction of the aircraft, then waiting until the last moment to turn on the tracking radar to correct the trajectory.

This deadly game of measures and countermeasures, feints and deceptions mixed in with an occa­sional bullet between the eyes, is the standard stuff of electronic com­bat. The objective is seldom to win a direct duel with the enemy. More often, the electronic warriors are satisfied if they can pull the enemy off balance sufficiently to allow some main battle event, such as at­tack of an enemy airfield, to succeed. Each side tries to preserve the electromagnetic spectrum for its own use while degrading, disrupt­ing, or—if the odds are right—de­stroying the opponent’s radar, com­munications, and other electronic assets.

A probing pulse from a ground radar can be either a threat or an opportunity. If the seeker stays on the air long enough, an antiradiation missile can be sent riding down his beam. A jammer can flood his radar screen with static. Alternatively, the penetrator might manipulate the sig­nal bouncing back to the defender’s antenna to feed him false informa­tion.

Measures and Countermeasures

In the 1960s, the radar-SAM com­bination forced penetrators to low altitudes where they could screen themselves behind natural terrain and the curvature of the earth. The fighters began to carry ECM pods routinely for electronic cover, then upgraded to “smart” frequency-hopping pods that adjusted auto­matically to the jamming require­ments of the moment. Defenders soon took the edge off low-level tac­tics with airborne pulse Doppler technology that could look down and pick out low flyers from the ground clutter on the radarscopes. The tactical electronic environment grew in density as well as in com­plexity. It is said that combatants in a European war would have to con- tend with a million pulses of electro­magnetic energy per second.

In the fifteen years since Line­backer II, the jammers and the Weasels have improved their weap­ons and added to their bag of tricks, but so have the Soviet-equipped shooters on the ground. This is es­pecially true along the Warsaw Pact border with Western Europe, where the Soviets have concentrated a thick barrier of their best mobile SAMs (see accompanying dia­gram) and state-of-the-art AAA guns like the ZSU-X, which can shoot on the run.

The Soviet Integrated Air De­fense System (IADS) has 7,000 ra­dars for early warning and ground-controlled intercept, 13,000 SAM launchers, 12,000 antiaircraft artil­lery pieces, and 5,300 fighter-inter­ceptor aircraft. Part of this is older equipment. Even the SA-2, up­graded several times since Line­backer II, is still in service at some 350 sites. But some of the newer SAMs are controlled by frequency-hopping monopulse radar, which reads range and direction from the same return and which welcomes a garden-variety jammer strobe as one more bit of useful information. Vietnam-era tactics will not beat this grid.

“There’s nothing today that I’d call a Soviet death dot—a weapon that can follow you into the bowels of the earth—but it takes more than maneuvering to survive,” says Col. Richard M. Atchison, Director of Electronic Combat Operations in the Office of the DCS/Plans and Op­erations at Hq. USAF “There is no one thing you can put on an airplane that is sufficient by itself to protect you. It takes a mix of equipment, strategy, and tactics.”

It’s an open question whether the modern Weasels with their F-4G air­craft and High-Speed Antiradiation Missiles (HARMs) would be able to intimidate these SAM operators.

Soviet doctrine prescribes emission control, but does not leave the op­erators much discretion to interpret orders. If they shut down at an unau­thorized time, they face a firing squad. But that’s the next day or the next week. The threat of the Wea­sels is immediate. After a few near­by sites are blown away, the disci­pline of the SAM operators would be tested severely.

To screen its own forces in battle and to degrade the opponent’s com­mand and control, the Soviet Union is prepared to conduct large-scale jamming of radars and communica­tions. Its main airborne platforms would be the 11-20 Coot-A and the An-12 Cub-C and D—modified ver­sions of turboprop transports—and the J and K models of the Mi-8 Hip medium helicopter. Ground-based jammers, assigned to radio-elec­tronic combat battalions of the Army, proliferate.

The New “Mainstay” AWACS

The old Soviet airborne warning and control system, the Tu-126 Moss, is limited in effectiveness and has not been a major concern for the West. The new Mainstay AWACS, topped by a “Flat Jack” radome, seems to be another matter. “Now in production, this modified I1-76TD has a true overland look-down capa­bility,” says the latest edition of So­viet Military Power, published by the US Defense Department in March. “In addition to a new identi­fication, friend or foe [1FF] system, this aircraft may have a comprehen­sive electronic countermeasures complement.”

The Russians have been practic­ing this game, which they call “radio-electronic combat,” since the time of the czars (they jammed a Japanese radio with a spark trans­mitter in 1904), and they are adept at it. Their better systems rank with the best.

Soviet technology in this field sorts into three time categories, says Brig. Gen. John A. Corder, Di­rector of Electronic Combat for Air Staff R&D. Systems brought out in the 1960s and early 1970s were “poor to fair,” but were produced in large numbers.

“Beginning in the mid- 1970s, with the advent of monopulse and pulse Doppler processing, the ability [of their airborne radars] to look down and find things in the clutter was improved,” General Corder says. The Soviets had not yet mated these radar returns with weapons for a look-down/shoot-down capability, but “no longer could you run around at low altitude and not be found. And with monopulse processing, the ability to hide yourself in angle [azimuth and elevation] was de­graded. I’d start calling this pretty good technology, and the numbers were still there.” The MiG-23 inter­ceptor represents this category.

In the 1980s, General Corder says, “we begin to see excellent technology in terms of look-down/ shoot-down from an airborne threat. The numbers are fairly low right now. They probably won’t be significant until the early 1990s, and there won’t be as many of them as we’ve seen before, I don’t think, because they cost a lot of money.”

Soviet Military Power also re­ports progress by the USSR on ra­dio-frequency (RF) weapons. Sev­eral applications are possible, one of them being the degradation of military electronics. Soviet re­searchers have generated single pulses of better than a billion watts and have sustained repetitive pulses of greater than 100 million watts.

Punching Holes in IADS

Meanwhile, the US Air Force has been making some progress of its own. It still has some shortcomings, but, all in all, is probably better pre­pared for electronic combat than at any time in the past. Its major elec­tronic combat aircraft have come into service in the past ten years. Most of its countermeasures equip­ment has been upgraded or is being upgraded now. Indications are that the United States will be able, in the years ahead, to stretch out the slim lead it now holds over the Soviet Union in this area. Electronic com­bat has also become a regular part of USAF training and exercises, which contributes both to aircrew preparation and to the mindset it takes to win in the game of measures and countermeasures.

The improvements that meet the eye most readily are those in the area of offensive electronic combat, systems and tactics that prevent the enemy’s use of his radars and ra­dios. Individual airplanes in the tac­tical fleet would go into battle with some countermeasures on board: jammers good enough to set up a local electronic fog, chaff to foil ra­dars, and flares to counter threats from the infrared portion of the electromagnetic spectrum. The F- 15 has its countermeasures equip­ment tucked neatly inside as part of its Tactical Electronic Warfare Sys­tem (TEWS), but most aircraft car­ry their ECM equipment in external pods. These pods, like the radars they work against, are agile fre­quency hoppers.

Jamming is a matter of how much electronic energy the source can blast into the contested frequency. The jammer can focus his power for intensity or diffuse it for broad cov­erage, but either way, it takes con­siderable power to dominate the en­emy’s large emitters on the ground and control the spectrum over a lot of territory. It isn’t practical for fighters to carry jamming sets big enough to do all this. That’s a job for escort aircraft that specialize in jamming.

The EF-111A Raven, operational since 1981, can reach out for long distances and disrupt early warning and GCI radars. It is effective against the densest electronic de­fenses known. Raven can act as a stand-off jammer, or it can escort the penetrating force into the battle area. It took part in last year’s US action against Libya. The EC-130H Compass Call, introduced in 1983, is a communications jammer that would work from standoff range against the enemy’s command and control net. These two jamming platforms perform extremely well, but there aren’t many of them. Only forty-two of the EF-111As were ever assembled. The Air Force has just ten Compass Calls, with six more coming.

“First in, last out,” according to their motto, will be the Wild Weasels. They have been flying the F-4G variant of the Phantom since 1978. Weasels still carry the Shrike and can employ several other mis­siles, but preferred ordnance is the AGM-88A HARM, on which the Air Force is currently taking deliveries. HARM has three times the range of the Shrike, plus supersonic speed. To augment the Weasels, the Air Force is outfitting some F-16s to launch Shrikes and HARMs.

The Less-Noticed Side

Defensive electronic combat is the less-noticed side of the busi­ness, but vital to the combat pilot who looks to his radar warning set to tell him when he’s being “paint­ed” by the bad guys. Current RHAW (radar homing and warning) gear does a pretty good job of alert­ing the aircrews to danger and re­porting the nature and bearing of the threat. These sets identify enemy equipment by scanning, their stored memories for an emissions sig­nature that matches what the receiv­ers are picking up. Reprogramming these systems consumes time, which could be critical. Conse­quently, a program to provide Area Reprogramming Capability (ARC) in the field is being followed with considerable interest.

Several systems normally re­garded as belonging to the domain of C3 are quite relevant to electronic combat as well. These include the Have Quick tactical radio, whose transmitters jump to a new frequen­cy every tenth of a second to stay ahead of enemy jammers. The Mark XV IFF (identification, friend or foe) system has finally cleared a multinational tangle of delays, and its installation in thousands of plat­forms will begin around 1993. It will meet a long-standing need for a bet­ter way to sort out, electronically, who’s who. One of the most impor­tant aircraft in any combat theater will be the E-3 AWACS. With its antijam radar, massive tracking and data-processing power, and deep look at the air battle, the E-3 would have a profound influence on the various jammers, jammees, pen­etrators, interceptors, and ground-based defenders.

Good as these forces and systems are, they cannot defeat the entire electronic order of battle arrayed against them. The emitters and ra­dar-controlled weapons are too nu­merous for that. The Air Force would not be able to attack all of them at once, even if that were the strategy, which it isn’t. The function of the electronic warriors in a Euro­pean war would be to punch holes in the Soviet IADS.

The concept of taking on enemy emitters incrementally is seen, for example, in the Air Staffs current thinking about how to deal with the problem of Soviet monopulse ra­dars. Technological responses are possible, and some countermea­sures are nearing full-scale develop­ment. A pure “systems” solution, however, would be too expensive to provide for the large tactical force. New countermeasures will be em­ployed, as feasible, along with exist­ing countermeasures, tactics, the inherent capabilities of modern fighters, skill, and cunning. This strategy looks at the problem in a total context.

IADS must first pick up the pen­etrators, then feed the information through the command and control network to the interceptors, SAMs, and guns. The interceptors and the firing batteries have to choose their targets, acquire, track, lock onto, and hit them—all while the fast-moving aircraft are within range of the weapons. This chain of events is a critical path; each function must succeed for the intercept to suc­ceed.

“If we can break the chain at any point, we will defeat the air de­fenses,” says a recently cleared Pentagon briefing. “However, monopulse angle tracking is em­ployed only during radar tracking and missile guidance, and counter­ing it is, therefore, only part of the problem we must solve. We are cer­tainly not always compelled to at­tack whatever might be the stron­gest element of the process at a given point in time. Nor must we necessarily attack all of the seg­ments at once. . . . This broad ap­proach is expected not to defeat any segment of the air defense process completely, but rather to reduce its effectiveness to the point where our mission success is maximized.”

Inside and Integrated

The Air Force’s top procurement priority for electronic combat is self-protection equipment. Over the years, the Air Force has bought nu­merous specialized systems to meet specific threats and now owns an extensive assortment of warning, jamming, and dispensing gear. Most of the fleet carries this equipment in external pods, which ties up weap­on stations and creates drag. Never­theless, pod mods will continue for awhile because the cost of retrofit­ting all of the airplanes with internal ECM is prohibitive. Aircraft of the future, however, will have internal, fully integrated countermeasures suites.

The F-15 already has internal ECM with its Tactical Electronic Warfare System (TEWS), and the Advanced Self-Protection Jammer (ASPJ) will provide it for some F-16s and several types of Navy air­planes. But the real vision of the future is the Integrated Electronic Warfare System (INEWS), which the Air Force and the Navy are de­veloping jointly for their next gener­ation of tactical fighters.

Whereas countermeasures have traditionally been add-ons or retro­fits, INEWS will see everything built together to work together, with the electronics almost as organic to the aircraft as the engines and the airfoils. “INEWS emphasizes jointness and commonality so that parts of the system will be usable in the Army’s LHX [new light helicop­ter family] and other Air Force sys­tems besides ATF,” says Col. George R. Winters II of the Depu­tate for Reconnaissance, Strike, and Electronic Warfare at USAF’s Aeronautical Systems Division.

The technologies, especially VHSIC (very-high-speed integrated circuitry), that underlie INEWS may enable the United States to stretch out its lead again in the mea­sures-countermeasures game. Gen­eral Corder says that Soviet tech­nology in electronic combat now trails the US by a year or two, with the biggest lag seen in packaging. When designers are limited in their ability to combine components in tight spaces, they are forced to make their airframes larger or resort to other ways of compensating.

Even for US designers, who lead the league in that regard, it is not easy to get countermeasures suites down to pocket size. The ASPJ pro­gram, for example, gives fighters about the same ECM capability as that in B-52 bombers. In the BUFF, this equipment weighs 700 pounds and occupies fourteen cubic feet. ASPJ does it with 300 pounds in three cubic feet. At 100 pounds per cubic foot, it’s a snug fit. (By com­parison, a cubic foot of solid alumi­num weighs around 112 pounds.)

The Game Goes On

Between wars, the measures-countermeasures struggle con­tinues in less violent form, with each side seeking new advantages and probing for revelations about the electronic progress of the op­position. “You don’t wait to learn his capabilities and vulnerabilities in the field,” Colonel Atchison says. One subset of the game, Electronic Support Measures, consists of fer­reting out such information.

The Soviet Union took note in 1986 when HARM missiles fired by US airmen scored direct hits on Libyan air defenses. And Soviet use of radio-electronic combat in Af­ghanistan has been of tremendous interest to US intelligence. This part of the game does not stop with observation. Some of the Soviet systems of most concern to the West are based on technology stolen from the United States.

On the technology front in the cold war of measures and counter­measures, the warriors also win some and lose some. An apparent casualty—although not yet certified as a fatality—is the Precision Loca­tion Strike System (PLSS). Its role was to be deep-look detection and targeting of enemy radars. “Unfor­tunately, the complex task of pro­cessing and analyzing the vast number of signals picked up during fast-paced combat operations has proven to be more difficult than an­ticipated,” the Defense Department reported to Congress earlier this year.

Most known developments are going well, though, and it’s gener­ally assumed that still more are in progress behind the cover of se­crecy. Countermeasures tend to be perishable once the enemy has seen them used, so electronic warriors often keep their best tricks hidden until they can spring them with sur­prise at a telling moment.

Sometimes the most effective countermeasures are the simple ones, perhaps not from the world of advanced technology at all. Colonel Atchison describes such an in­stance where ingenuity was the an­swer. When the heat-seeking SA-7 missile was introduced, it gave North Vietnamese ground troops a potent weapon against aircraft.

An AC-130 gunship crew over Fire Base English in 1972 knew about the SA-7 and was ready for it. As the SA-7 rose up from the trees and homed on the airplane, one of the crewmen fired a round from a Very pistol out the rear door. Sure enough, the missile swung toward the hot-burning flare and away from the gunship, which proceeded about its business. Score one for skill and cunning, and stand by for the next move.

Works in Progress

• EF-111A Upgrade. Updates the pro­cessing and jamming subsystem of the EF-111A Raven radar-jamming aircraft. Contractor is Eaton AIL. Flight tests begin in January 1988.

• F-4G Wild Weasel. Only certain E-model Phantoms can be converted to F-4Gs, and available airframes are getting scarcer. USAF will buy eighteen more in 1988. A Performance Upgrade Program (PUP) is developing a new signal pro­cessor for additional memory and speed, and a new direction receiver group will add to the F-4G’s capability to process and handle threats of the 1990s. Prime PUP contractor is McDonnell Douglas, with Sperry and E-Systems subcontracting.

• ASPJ. The Airborne Self-Protection Jammer will provide internal counter­measures for USAF’s F-16 and several types of Navy aircraft. The Pentagon says the program is now on track and that test results look good. Deliveries begin in 1990. Contractors are ITT and Wes­tinghouse.

• INEWS. Supposedly the wave of the future, the Integrated Electronic Warfare System will equip USAF’s ATF and the Navy’s ATA. A fully integrated and versatile electronics suite that pulls everything to­gether. Two joint-venture teams: Sanders! GE and TRW/Westinghouse.

• ECM Pods. The older of USAF’s two main ECM pods, the ALQ-119, is getting a kit upgrade, after which it will be re­designated the ALQ-184. Contractor is Raytheon. Production of the newer ALQ-131 ECM pod continues by Wes­tinghouse.

• EC-130H Compass Call. The Air Force has ten of these aircraft for communica­tions jamming and will acquire six more in 1987. Contractor is Lockheed.

• AGM-136A Tacit Rainbow. Joint-ser­vice ECM drone in development by Nor­throp. The Air Force has the lead on the air-launched version, and the Army is working on a ground-launched one.

• Area Reprogramming Capability (ARC). Will give theater commands the much-needed capability to reprogram electronic software locally as the threat changes. Reprogramming must currently be done Stateside.

The ABCs of Electronic Combat

• EW. Electronic Warfare. The use of electromagnetic energy to determine, ex­ploit, reduce, or prevent hostile use of the electromagnetic spectrum. Subsets in­clude ECM, ECCM. and ESM.

• ECM. Electronic Countermeasures. Jamming and deception of enemy elec­tronics. ECM systems include EF-111 jam­ming aircraft and jammers, flares, and chaff carried by individual fighters.

• ECCM. Electronic Counter-Counter­measures. The response to ECM Seeks to protect ones own use of the electromag­netic spectrum and avoid radar-controlled attack by the enemy. Examples include Have Quick antijam radios.

• ESM. Electronic Support Measures. Use of a systems electronic signature to learn the enemy’s electronic order of battle, including location and capability of his emitters. ESM systems include RF-4C TEREC aircraft.

• SEAD. Suppression of Enemy Air De­fenses. Physical and electronic measures to neutralize, degrade, or destroy enemy radar emitters, SAM sites, and gun-laying assets. SEAD systems include F-4G Wild Weasels with AGM-88A High-Speed Anti-radiation Missiles (HARMS). Also AGM-136A Tacit Rainbow drone, now in devel­opment.

• C3CM. Command Control and Com­munications Countermeasures. Actions to deny the enemy information and to de­stroy or degrade his C3 network. includes Operations Security (OPSEC) measures and EC-130H Compass Call communica­tions-jamming aircraft.