ECM / Radar Jamming Techniques and Effectiveness

[Tintruder]

I'm a former USMC pilot with experience in the A4 and A6.

I understand the theory behind all the ECM Gear and even had the chance to use it in combat.

But I still understand far less than I know.

So to the experts here, exactly what does all this stuff do?

If the F-35 and F22 are so magical, why are we buying F-18G "Growlers"?

What do Prowlers do? If F18s, especially the E and F models have such wonderful ECM Gear, why are the prowlers up there?

How effective is this stuff?

Because it sure seems to me that if the Prowlers and Growlers REALLY do what they supposedly do, you could just fly old non-stealth jets with a Prowler/Growler doing Escort Jamming.

When the USAF retired the EF111s, the EA-6B requirements went way up with the USMC expanding to 4 full squadrons from just 1 and control of the prowlers at the JCS / "National Asset" level.

So how about a discussion of the current State of the Art and Doctrine for the use of EA-6B and F-18G and what their absence or presence means to the individual aircrew with the gizmos on board the typical F15, F16, F18, Harrier, Helo (and the F22 & F35)

What is more important, Jamming or Stealth?

Why don't we have a missile that homes on Airborne Radar? I know the SA-6 supposedly had a Home-on-Jam function, but all you had to do with that is jam on a racetrack path about 30 miles from the emitter, watch them launch and fall under your nose. Hair-raising but functional.

Feel free to discuss other stuff like USAF assets, drones etc.

Perhaps someone can explain why, despite copious EW and ECM Gear, Jammers, Chaff and Flares, how guys managed to get hit by SAMs during the Gulf War and after??? AAA I can understand if you're flying low and too close, or just unlucky at altitude, but as I recall the ALQ-126B cost $1M each and the Intruder carried 2 of them. They are still loaded in the Hornets today. WTF good are they?

EW Experts, please comment.

 

[Jemiba]

Welcome Tintruder, nice to have people wich real flight experience here !
You've asked a number of questions, perhaps some will be answered in another section, for example
about the SA-6 or a home-on -jam A2A missiles. Don't know, if you already searched the forum here,
some answers may already be given in other threads, at least partially.
Just take your time looking around, a lot of things were already discussed, just be careful with keywords
like "F-35", it may mean to open a can of worms !

 

[Bill Walker]

Just a few general comments, based on some theory courses I sometimes teach. I'm not up enough on the EF-18 to go into details.

ECM takes several forms, including detection, and several forms of jamming. Most combat aircraft carry some classification gear, and short range, system specific, jamming. Nowadays system specific means not only specific to a given piece of bad guy hardware, but also specific to particular phases of operation of that hardware: scan mode, lock on mode, terminal homing mode, etc. Given weight and space limitations, the combat aircraft can only carry so many of these, based on what concerns you the most. This is usually short range stuff, geared for the "after lock on" phases of the scenario.

If you are not sure exactly what systems you may encounter, it takes a human in the loop, plus more extensive classification/detection gear to mount a defensive or offensive response. Hence aircraft like an EF-18: full time system operator, lots more gear, and lots more broadcasting power (which usually means physically larger antennas). More broadcasting power can also cover a larger area, allowing you to defend aircraft besides your own, and allow you to prevent lock on in the first place.

In any event, ECM is sort of statistical - it makes the other guy's electronics less effective, but rarely totally defeats them in each and every scenario. If you are close enough to the other guy's missile when it launches, it is more likely to penetrate your ECM. Also, if the other guy can launch multiple missiles, some per cent may make it through. Effective ECM lowers that percentage, but it rarely gets to zero.

IMHO, stealth and ECM are complimentary. Stealth helps you delay initial electronic detection by the other guy. Passive ECM can also help in this early stage, giving you information on the other guy's order of battle and his disposal of forces. Active ECM takes over after the other guy has determined you are there (electronically or otherwise).

Concerning homing on jamming, many active jammers present a spread or otherwise false target, rather than the pin-point you need for the relatively small war heads of modern missiles. When it comes to active jamming in the last phases of the approaching missile's flight, a miss is as good as a mile, so that is what many ECM systems are designed to create. The extreme example of this is the RF decoy. I suspect that in your stand off jamming example against the SA6 your equipment may have tricked the SA6 system range calculations, forcing a premature launch. In all these examples, you want the other guy to receive your jamming signals - instead of real returns from your aircraft.

But all this does remind me of a question I have had for some time - why is Russia spending so much time and money on long range anti-AWACS AAMs, while US/NATO doesn't seem to bother? What have I missed?

 

[lastdingo]

There are actually books about that;
EW101, EW 102 and I think even a third part.

Ask your library if it participates in interlibrary lending, for this may make reading these expensive books real cheap.

 

[SOC]

But all this does remind me of a question I have had for some time - why is Russia spending so much time and money on long range anti-AWACS AAMs, while US/NATO doesn't seem to bother? What have I missed?

Russian AEW platforms are primarily defensive assets tasked to support interceptors and assist in the air defense role. The E-3, on the other hand, is an offensive asset used to actively aid combat sorties in a given conflict. Russia is upgrading the A-50 and may well end up using it in a more offensive-minded capacity, but numbers are pretty limited. So, given that they recognize the Western reliance on assets such as AEW and ISR platforms, Russia coming up with a way to counter that advantage is logical. Plus, it's another toy they can sell on the open market.

The US did at one point spend some effort in trying to counter Soviet AEW platforms, but it was with nuclear war in mind. Two ideas involved armed SR-71As, there was an AAM project, and I think the F-117 might've briefly been considered but ultimately rejected.

 

[Sea Skimmer]

ECM comes in two basic flavors, noise jamming that simply attempts to drown out any relevant signal, and trickery techniques that distort returns in a half dozen or so different ways. Ideally you use both together. Noise jamming will let other forms of jamming become more effective, because the enemy radar single processing computers already have more bullshit to deal with. This requires that they turn down the sensitivity of the radar, making it harder to filter out the various tricks. It also just keeps the enemy busy, which is becoming less relevant as radars become more automated. Dated Soviet systems used in the Gulf War still required a lot of operator control.
At some level noise jamming will always work, given enough power compared to enemy radar power, range to target and the RCS of the targeted aircraft.
The trickery techniques depend on knowing something about the enemy radar. They can vary from being made useless by a slight change to enemy software, to completely negating tracking techniques. They often require specialist hardware features on the jammers.
The point of stealth was that raw jammer power is very expensive to field, and impossible to employ against the vast numbers of radars Soviet style air defenses employ. This was one very reason why the Soviets had so many and so many different radars. Trickery meanwhile required constant ELINT of new enemy radars, and constant fielding of new hardware, and now more so software, and constant testing all of which cost a colossal amount of money.
Stealth is dependent on the power and wavelength of the enemy radar, but not its precise operating function. If you are stealthy against one X-band radar, you’ll be about the same amount of stealth against another one of similar power-aperture. That’s very handy.
That was the idea in the 1970s too, to get away from a month by month struggle as the USAF and USN engaged in over North Vietnam to adapt better ECM and chaff techniques.
Jamming planes are required because they have the power to do raw power noise jamming, and they can jam lots of threats at once. The pod on a jet can only jam one a few threats immediately relevant to that aircraft and with fairly low power. Jamming plans also jam enemy communications, both voice radio and datalinks. The Prower and Growler have dedicated pods for this, the EF-111 and B-52 had internal gear for it. I can’t think of any fighter type pod with a claimed capability to do so.
Stealth reduces the radar signature of the plane, which means even if the enemy still can see it; less radiated jamming power will be required to effectively hide that plane. That means the jamming works closer to the enemy SAM site. Ideally it works so well you can fly between the SAM sites, and while fired on, you won't be hit. This is why jammers have often been used alongside stealth. It is not a one or the other situation, unless money is very short in which case you are most likely an air force which cannot afford either. Air power is absurdly expensive, this is why the world has never ever had more then a handful of top end peer air forces at the same time.
As for home on jam, this requires a missile to recognize that it is being jammed. That’s fairly easy against noise jamming, and early fighter jammers were not very advanced. This is also why jammer planes would prefer to stay way from enemy SAMs and jam from a distance, though this does make the jamming less effective at the same time. With deception-trickery types of jamming meanwhile the missile may never know it is being jammed, and fly off to hit an imaginary target in the sky. That's why home on jam didn't negate all jamming. Both sides got more advanced in a never ending cycle.
The missiles Iraq and the Serbs had were obsolete, in many cases had been physically exploited by US intelligence, and generally had only the most basic of home on jam functions if any at all. Modern missiles are a lot more capable. However a very simple countermeasure to home on jam has been to add towed decoys to fighters, which include the radio jammer antenna. The home on jam missile will blowup the towed decoy and leave the fighter intact. usually fighters equipped with such a system have two towed decoys so they can stream a second one if the first blows up.
Oh and the latest towed decoys now have control fins, so they can steer themselves towards the enemy missile and increase their chance of taking the hit instead of the jet.

 

[Sea Skimmer]

Russian AEW platforms are primarily defensive assets tasked to support interceptors and assist in the air defense role. The E-3, on the other hand, is an offensive asset used to actively aid combat sorties in a given conflict. Russia is upgrading the A-50 and may well end up using it in a more offensive-minded capacity, but numbers are pretty limited.

They have 25 in service, that isn't very limited compared to the USAF with 32 x E-3s. The new upgrade is well, a completely new aircraft in any functional sense, while the US still has no real program to replace the E-3 and its less then totally modernized systems.


The US does have a very large number of E-2 Hawkeyes, but the performance of the UHF radar on Hawkeye over land is also pretty bad, and this is only partly mitigated with the new radar on E-2D. Since it only has a tiny mission crew a Hawkeye also needs to downlink its data to E-3 or warship to be decently exploited. That's the big limitation of the A-50 itself, the operator crew is limited, no word on if A-50U will change that or not that I've heard.

 

[lastdingo]

Let's not forget that there was still the F-14/APG-71/AIM-54 combo, and a detached flight of these supported by a fighter wing could have messed with Soviet AEW all over Central Europe.

--------

About numbers; the UK and NATO operate E-3s as well, and the USN covered much of the North Atlantic with E-2s and surface ship radars.
The Soviets were also more serious about strategic air defence, and Russia is huge even if we only take the seriously populated regions into account.

 

[Blaze1]

In any event, ECM is sort of statistical - it makes the other guy's electronics less effective, but rarely totally defeats them in each and every scenario. If you are close enough to the other guy's missile when it launches, it is more likely to penetrate your ECM. Also, if the other guy can launch multiple missiles, some per cent may make it through. Effective ECM lowers that percentage, but it rarely gets to zero.

You mentioned ECM being 'sort of statistical' and I was wondering a scenario of a missile be launched at an aircraft and the aircraft using jamming techniques in an attempt to defeat the threat. If this scenario was played out multiple time under the exact same conditions of range. altitudes, other kinematics, atmosphere, environment, background and solar radiation emission, would the results differ due to the statistical aspect you mentioned?

 

[Dragon029]

I'm not Bill Walker, but if you had everything the same (including the same orientation of emitter / receiver arrays, frequencies, power outputs, etc), then in practical terms, the results shouldn't differ by any noticeable degree. The more power you emit the more definitive the result should be too; if you hit them (a real, modern day system) with a megawatt maser, you'd have a pretty solid impact on the enemy's ability to fight; far more so than if you used a 5 kilowatt radar jammer.

 

[Blaze1]

I'm not Bill Walker, but if you had everything the same (including the same orientation of emitter / receiver arrays, frequencies, power outputs, etc), then in practical terms, the results shouldn't differ by any noticeable degree. The more power you emit the more definitive the result should be too; if you hit them (a real, modern day system) with a megawatt maser, you'd have a pretty solid impact on the enemy's ability to fight; far more so than if you used a 5 kilowatt radar jammer.

Would this also apply for deception techniques?

 

[Bill Walker]

I am Bill Walker, and from years of test experience it is VERY hard to duplicate everything you mentioned in a test set up. Yes, I guess if everything was EXACTLY the same the results of jamming or deception would be exactly the same. But trying to get into EXACTLY the same tactical situation (ranges, relative bearings, timing of launches and start of jamming, etc etc) would, to all practical purposes, be impossible. So, effectiveness of jamming and deception is often scored statistically.

The comment about megawatt lasers vs, kilowatt jammers is interesting. The variables we are talking about will change the energy put on the target (from jammer or directed energy weapon). If you have a big energy margin (i.e. at very close ranges) this becomes less of an issue. But even the megawatt laser will still have a "fuzzy" boundary between kill and not-kill. It will just be a bit further out that an RF jammer.

 

[Maury Markowitz]

If the F-35 and F22 are so magical, why are we buying F-18G "Growlers"?

One reason, oft forgotten, is that aircraft aren't the only targets for radars. I understand that much of the EF-111 work during GF1 was aimed at Iraqi artillery radars, not anti-aircraft systems. No amount of stealth on your side will help you defeat them tracking their own rounds outbound.

That said, one can imagine few platforms worse suited to the ECM role than the F-18. The ECM role demands long flights so you can track the radars over the "time dimension", and the F-18, even the E, has a laughably short loiter time even in the fighter role (there's one reason the Navy wanted to keep their F-14's).

But I guess I'm tiling at windmills. It appears the Navy is intent on reducing their fleet, so I expect future CV's will be armed with a single E/A/R/K/F-18G that is the size of a C-5.

 

[Blaze1]

I am Bill Walker, and from years of test experience it is VERY hard to duplicate everything you mentioned in a test set up. Yes, I guess if everything was EXACTLY the same the results of jamming or deception would be exactly the same. But trying to get into EXACTLY the same tactical situation (ranges, relative bearings, timing of launches and start of jamming, etc etc) would, to all practical purposes, be impossible. So, effectiveness of jamming and deception is often scored statistically.

The comment about megawatt lasers vs, kilowatt jammers is interesting. The variables we are talking about will change the energy put on the target (from jammer or directed energy weapon). If you have a big energy margin (i.e. at very close ranges) this becomes less of an issue. But even the megawatt laser will still have a "fuzzy" boundary between kill and not-kill. It will just be a bit further out that an RF jammer.

I hear that announced with authority


Thanks for explanation Bill.

 

[stealthflanker]

Greetings.

Hmm and good to see ECM related topics, wish i could contribute something. But for now all i have is a question.

Can one use cross eye technique as standoff jammer ? E.g jamming from over hundreds of kilometers against SAM engagement radar instead of being only as "self protection" By jamming homing seekers or short range systems.

I asked because of my recent discussion with someone regarding effectiveness of cross eye jamming against today's monopulse radar. I agree with most of his points except when it comes to long range SAM engagement radar. Based on my readings at some books (Introduction to Electronic Defense by Filippo Neri and EW-101) The Cross eye requires quite high Jammer to Signal Ratio in order of 20 Db (Though i know that there's paper stating that figure is conservative, 10-15 Db is "enough") Without preceeding "pull" (RGPO or VGPO or perhaps simple amplified replica of the signal) To seduce tracking radar away from target's skin return.

With preceeding "pull" According to Barton and T Sherman's book about monopulse, this J/S ratio can be reduced to be about 6, but this is not practical for self defense scenario where time is short.

But well this is standoff jamming question.

In my view however with "pull" There might be possibility that standoff cross eye is possible. However modern radar is expected to have some form of anti "seduction" Technique like leading edge tracker to sniff real target return, which later can be responded with change of tactics or Home on Jam missiles complimenting conventionally guided missile.

Hmm thoughts and additions are welcome.

 

[KJ_Lesnick]

Doesn't noise jamming increase the odds of being attacked by home-on-jam technology?

 

[stealthflanker]

Doesn't noise jamming increase the odds of being attacked by home-on-jam technology?

From my view at least, yes.

Thus why noise jamming is usually a job for large stand-off jamming aircraft with high power jammer and jam from beyond the range of enemy weapons.

 

[KJ_Lesnick]

Russian AEW platforms are primarily defensive assets tasked to support interceptors and assist in the air defense role. The E-3, on the other hand, is an offensive asset used to actively aid combat sorties in a given conflict.

Why didn't we use them for both?