ECM in DCS

[Cmptohocah]

From my limited knowledge, which comes from that 1962 US Navy film, of ECM there are at least two types of ECM that affect radars:

1. Signal-multipliying 

2. Lock-breaking

 

My question: which effects are being simulated in DCS when it comes to ECM?

 

Interestingly the same movie claims that the performance degradation of the radars can be up to two thirds of normal operation, when ECM is on.

[QuiGon]

Depends on what is being jammed. Jamming in DCS behaves completely different against AI than it does against other players.

Against the AI it reduces their launch range. I'm not entirely sure if it does lock-braking as well, but at least with the Hornet's jammer this seems to be the case.

Against other players, the jamming effect entirely depends on the recieving aircraft that needs to simulate jamming effects on its own systems. In the jamming aircraft the implementation of jamming is very simple. It's just a boolean that is either true (jammer on) or false (jammer off). This status gets transmitted over the network in Multiplayer and it's on the recieving side (the aircraft that gets jammed) to simulate jamming effects.

Most aircraft in DCS that have jamming effects implemented show some kind of noise jamming when being jammed (e.g. F-15, MiG-21, F/A-18). It denies range and IFF information.

Other aircraft show some other effects, like deception jamming that shows false contacts (M2000C). And some aircraft don't even show any jamming effects (yet) making them immune to jamming (F-14, F-16).

Edited November 15, 2021 by QuiGon

[Cmptohocah]

Hi @QuiGon,

I didn't formulate my post properly. What I should have written was: what kind of ECM is DCS trying to simulate?

 

Also, I am not sure why what is exact mechanics (funny wording since everything is electronic) of this noise jamming? It sounds a lot like repeating the orginal signals and the sending them back amplified, but then a lot of other effects are missing for this type of jamming.

[Northstar98]

On 6/14/2021 at 9:18 PM, Cmptohocah said:

From my limited knowledge, which comes from that 1962 US Navy film, of ECM there are at least two types of ECM that affect radars:

1. Signal-multipliying 

2. Lock-breaking

My question: which effects are being simulated in DCS when it comes to ECM?

Pretty late to the party, but given ECM in DCS is more of a hot topic, I'll chime in.

That film concerns DECM systems; in DCS the only aircraft with any kind of DECM technique simulated (track-breaking) is the Hornet (EDIT: And now the F-16), which AFAIK only affects AI units (so far ground units and aircraft, haven't tested ships yet).

I'm guessing that how it works is that beyond the burn-through range, there's a probability that the jammer will break the lock within a certain amount of time. Inside the burn-through range, track-breaking is ineffective.

The only module that has DECM effects modelled on its RADAR is the Mirage 2000; when in the Mirage's PSIC mode (STT), it treats all other jammers as track-breaking DECM systems performing a range gate pull-off (at least according to the manual), causing the contact to erroneously migrate in range across the display, and sometimes dropping the lock (see page 313 of the manual).

 

Every other jammer in DCS is modelled as continuous noise jamming (which is more of an OECM technique, the film referred to it as 'the brute force method', and is perfect for HOJ missiles), this form of jamming blasts out white noise, increasing the noise floor for the RADAR, reducing the SNR of the contact, potentially drowning the contact out in the noise. If jamming is strong enough, you can blank out entire sectors with noise (exploiting sidelobes).

In DCS this is treated as a simple fag: ECM = on and ECM = off and is simplified.

How it's displayed however is as follows:

• In FC3 aircraft, it produces a strobe (essentially a continuous line of contacts, occupying the entire instrumented range at the azimuth of the jammer). Though in the F-15, it presents several, hollowed out contacts (5? 6?). In the MiG-29s and Su-27/33 it will also cause the RADAR to drop into RWS from TWS. Once the jamming target is inside the burn-through range (and can be resolved), it will display as a normal contact.
• In the F-16CM, F/A-18C and Mirage 2000 (HFR mode only), noise jammers that the RADAR can't resolve the range show up with an angle-on-jam indication, once the target can be resolved in range (inside the burn-through range), it shows up as a regular contact:
  • In the F/A-18C this is a target in the AoJ dugout (Unknown HAFU-like symbol with an 'A' in the middle showing the target is angle only, 'J' to the left indicating jamming, there may be a letter to the right indicating it's being tracked by the TGP ('F')). Once the target's range is resolved, it displays as normal. See this video.
  • In the F-16C it's marked by 2 stacked, yellow chevrons at the top of the display, at the azimuth of the jammer. Once the jamming target's range is resolved it displays like any other, but with the 2 stacked chevrons placed over it. See this post.
  • In the Mirage 2000C (HFR mode only), this is a group of asterisks at the azimuth of the jamming target, additionally the number of rows of asterisks indicates jamming intensity (see page 311 of the manual).
• In aircraft that display raw RADAR video (F-5E-3, MiG-21bis and Mirage 2000C (BFR mode only), a jamming strobe is displayed.
  • In the F-5E-3 this is essentially a continuous unstable line of target 'bricks', similar to the MiG-29s and Su-27/33. I believe the RADAR will drop out of its STT mode so long as the jammer is beyond the burn-through range (presumably because the ambiguous range causes the range gate to not function properly, thus dropping the track). Note that the real display should be much more granular (like the Mirage's BFR mode).
  • In the MiG-21bis, this is continuous thin line, with a large number of target 'bricks' randomly drawn on top of it, the positions of the 'bricks' changes in range with each sweep. The strobe appears at all ranges.
  • In the Mirage 2000C (BFR mode only), it blanks out a sector along the azimuth of the jammer (see page 312 of the manual).

 

I'm unsure what the JF-17 does, (I remember contacts rapidly oscillating, possibly suggesting range ambiguity, but not sure).

Against AI, noise jamming decreases the lock-on and firing range of weapons by some amount.

 

Note: the burn-through range is the range at which the received power of the true skin return from the target = that of the jamming signal, inside the burn-through range, the received power from the skin return will be greater than the jamming signal. In DCS I'm unsure how this works exactly (whether it's just a preset range for a particular RADAR, or whether its actually doing the calculation).

Edited January 28, 2022 by Northstar98

[QuiGon]

16 hours ago, Northstar98 said:

Pretty late to the party, but given ECM in DCS is more of a hot topic, I'll chime in.

That film concerns DECM systems, in DCS the only aircraft with any kind of DECM technique simulated (track-breaking) is the Hornet, which AFAIK only affects AI aircraft, and ground based fire control RADARs (and maybe active RADAR seekers).

Every other jammer in DCS is modelled as continuous noise jamming (which is more of an OECM technique, the film referred to it as 'the brute force method', and is perfect for HOJ missiles), this jamming increases the noise floor for the RADAR, reducing the SNR of the contact, potentially drowning the contact out in the noise. In DCS this is treated as a simple fag: ECM = on and ECM = off.

I'm pretty sure the Hornet jammer doesn't do anything different than the other jammers and that ED just changed the behaviour of AI units reacting to this jammer.

But maybe I'm wrong and the Hornet serves as a testbed for a new API function for jamming that is not yet available for other aircraft and 3rd party devs. Even then ED had to implement new AI behaviour for he recieving units, telling them how to react to this.

Edited November 15, 2021 by QuiGon

[Lace]

Interesting stuff, it will be nice when fully implemented.

What about A-10C DECM vs Gun Dish (for example)? I've not really treated Shilkas as a real threat when jamming, as they always seem to track behind the a/c.

[Northstar98]

On 11/15/2021 at 9:25 AM, QuiGon said:

I'm pretty sure the Hornet jammer doesn't do anything different than the other jammers and that ED just changed the behaviour of AI units reacting to this jammer.

However the particulars are I don't know, but ECM in DCS should be more than a simple flag for ECM on and ECM off, we need to differentiate different techniques and different jammers, even if we have to have assumptions doing the heavy lifting when we don't know better.

It's a two-way street, both transmitters and receivers need improvement. How exactly it's implemented is another story.

On 11/15/2021 at 9:25 AM, QuiGon said:

But maybe I'm wrong and the Hornet serves as a testbed for a new API function for jamming that is not yet available for other aircraft and 3rd party devs. Even then ED had to implement new AI behaviour for he recieving units, telling them how to react to this.

That's what I hope, but as I said above, it needs to be a two way street for both ECM systems, the effects seen on the jammed RADAR and how the AI reacts.

On 11/15/2021 at 9:42 AM, Lace said:

What about A-10C DECM vs Gun Dish (for example)? I've not really treated Shilkas as a real threat when jamming, as they always seem to track behind the a/c.

AFAIK that RADAR IRL uses conical scanning where the beam is nutated about the target, producing an AM signal, the phase of which encodes position information that is used to make angle corrections in azimuth and elevation) and it's almost certain that track breaking DECM systems we have in DCS will be able to perform an inverse con-scan technique to defeat it (in this case, the RADAR will be driven away from the target).

That said the AI RADARs in DCS don't differentiate between how exactly they track targets (even if this is just a class, with the physical effects left as they are).

Also, the Shilka IRL has multiple modes of operation, in DCS though (well going by CA, no idea what the AI does) only one of these modes is simulated (as far as CA goes the RADAR doesn't actually seem to do anything beside trigger RWR warnings, as for the AI, the RADAR seems to act as a search RADAR, though the physical model doesn't seem to actually track targets).

• Fully automatic: RADAR tracks the target in both angle, and range, guns laid automatically.
• Semi-automatic: RADAR provides ranging, but target azimuth and elevation (and consequently azimuth/elevation rate) is tracked optically (this is done manually by the angle officer), guns laid automatically.
• Fully manual: target tracked optically, with range estimated, guns laid manually.
• Ground target mode (presumably this is like manual mode), guns laid manually.
• Memory mode: RADAR follows the predicted path of the target based on the last known parameters, guns laid automatically.
• Emergency mode (no idea what this entails), guns laid manually.

In CA we only have the fully manual mode available, with information about the target (range) and the aim point being controlled by difficulty options. In the 'target tracking mode' you're about half-way there to semi-automatic, but you have to update the range yourself (like a tank with an LRF), and manually lay the guns (with lead automatically introduced).

Edited January 25, 2022 by Northstar98

[QuiGon]

On 11/15/2021 at 12:48 PM, Northstar98 said:

However the particulars are I don't know, but ECM in DCS should be more than a simple flag for ECM on and ECM off, we need to differentiate different techniques and different jammers, even if we have to have assumptions doing the heavy lifting when we don't know better.

It's a two-way street, both transmitters and receivers need improvement. How exactly it's implemented is another story.

I'm totally with you there! DCS really needs proper ECM simulation! Unfortunately I don't see this happening in the foreseeable future.

Edit 12/28/2021: I can see this happening now

Edited December 28, 2021 by QuiGon

[Cmptohocah]

This also just crossed my mind:

Isn't the jammer supposed to blind your own radar too? I could be totally wrong on this one.

I also wonder, where did ED get the burn through distance? Does anyone have an idea?

[Harker]

This also just crossed my mind:
Isn't the jammer supposed to blind your own radar too? I could be totally wrong on this one.
I also wonder, where did ED get the burn through distance? Does anyone have an idea?

No idea where the burn through distance came from.

As for the jammer blinding your own radar, IRL, radars and jammers operate in discrete frequency channels (each channel is a collection of different frequencies), not all over their frequency spectrum. In most cases, the jammer can be set to operate outside the channels the radar is currently using (Radar priority) or the radar can be set to operate outside the the channels the jammer is using (Jammer priority). Prioritizing one system might compromise the other.

Take the following, extremely simplified scenario: You're tracking a target, with channel 5 (C5) selected and you are in Jammer priority. Your and your target's radars and jammers are different and may not use the same channel definitions. They start tracking you on a frequency that falls inside your C5. Thus, your Jammer goes online on C5 and your Radar is either blanked or forced into another channel, say C6. It tries to re-acquire the target with the frequencies in C6, but maybe your target's Jammer covers those, so your radar tries with C7 and manages to re-acquire the target, if their Jammer can't keep up or if your radar is able to use a range of frequencies they can't jam.

The opposite of that is that you're in Radar priority, on C5 and your target also tracks you with frequencies that fall within C5. Your jammer is not allowed to operate on C5, because of Radar priority, so it has little to no effect on your target's radar.

[GGTharos]

On 11/15/2021 at 1:13 PM, Cmptohocah said:

Isn't the jammer supposed to blind your own radar too? I could be totally wrong on this one.

Maybe, especially given that opposing forces can be operating near the same frequencies as your own radar.   This is why RWRs blank when the radar or jammer is operating and why radars blank during ECM operation.   That way everyone gets their little time window and it's transparent to you, the pilot.

On 11/15/2021 at 1:13 PM, Cmptohocah said:

I also wonder, where did ED get the burn through distance? Does anyone have an idea?

There's math for it out there but I don't think in-game burn-through has anything to do with it.  Also, it's heavily nuanced for a number of reasons, it's different for different systems and different techniques, etc.

[_Hoss]

There is a WRA in the Hornet (almost the same one in the Harrier) called an Interface Blanker. It turns on and off all RF emitting equipment in the aircraft, this determines their Duty Cycle. This keeps RF equipment from transmitting and receiving over each other. The ALQ-126 and the ALR-67 have a circuit card inside that is a memory for a threat library. It gives the DECM system a data base of "known" search, and fire control RADAR systems (surface and airborne), each have a distinct PRF/PW which is it's finger print. The system prioritizes, each for its effective range how lethal it is, and gives it a deception technique to Break lock, on a pulse for pulse basis. It raises the gain of the received pulse. That buries the actual return echo in the enemy RADAR receiver's noise so its not seen and injects the deception pulse in its place. Now the threat library knows NATO "western" radar systems and will not respond to them. But it will put an icon on the RHAW display, so you can tell if your wingie accidentally locks you up. Just because you put the system in Xmit/Repeat, does not mean it's going to transmit, the received signal has to have a signal strength strong enough to overcome the set sensitivity in your receiver to make it start repeating. DCS does not model DECM or ECM correctly in game, so debating on whether or not it's acting the way it should would be a exercise in futility. So being in a F/A-18 going up against a Iranian Tomcat, or Phantom you would need an AN/DLQ-3B to decieve their RADAR. That's not modeled right either.......

Cheers

Hoss

6641/6645/6639

[F-2]

AD0526139 Evaluation of ECM Pod Performance with Various Formations (Phase 1) 5/1/1973

TACTICAL FIGHTER WEAPONS CENTER NELLIS AFB NV 109 pages

ADB186362 U.S. Japan FS-X (FSX) Program Technology Bibliography: IEWS (Integrated Electronic Warfare System)

126 pages

 

ADB199302  U.S. Japan FS-X (FSX) Program Technical Abstracts, Volume 2, Subject: 17. Integrated Electronic Warfare System (IEWS). 
 

AERONAUTICAL SYSTEMS CENTER WRIGHT-PATTERSON AFB OH FS-X PROGRAM (JAPAN)

5/1/1995 6 pages

 

 

requesting these documents might provide some useful info for modeling