LDIRCM (and DIRCM) can involuntarily affect multiple missiles at the same time

[Big_Djck_Sergey]

In this topic I will be debunking the common misconception and myth that LDIRCM systems can only affect one and only missile, which is wrong.

Many people think that laser beams emitted by LDIRCM systems are like ‘single photon’ wide, which is not the case.

You see, laser beams have Diameter (commonly called ‘Beam Width’). The Laser beam is not 1 photon or few millimeters wide.

In terms of LDIRCM systems, they usually have Beam Divergence from 0.1 to 5 milliRadians.

If you take 1 mrad Divergence as an example, a beam would grow by about 1 mm per meter of travel — over 1000 m that’s roughly 1 m across. Increase divergence to 5 mrad, and that spot becomes ~5 m wide at 1 km. And vice versa, smaller divergence like 0.1–0.5 mrad results in tighter, more concentrated beams over long ranges.
Another example: for 0.1 mrad Divergence at 5mm Beam Waist the spot diameter is 105 mm at 1 kilometer distance.

Now note the following:

If multiple missiles are fired from the same launcher, they will follow roughly the same trajectory to the target.

Meaning even though the LDIRCM system is trying to blind only the first missile from said salvo, the rest of the missiles can also be involuntarily blinded by the laser beam, due to its Divergence. This is especially true for scenarios where both the launcher and the helicopter are stationary in space.

Exactly the same can happen when DIRCM is working against incoming missiles. (Even though its emitter relies on different principle of operation).

Bottom line is:
Assuming such systems are modelled realistically ingame, we would often see situations where DIRCM/LDIRCM would be overwhelmed only in rare cases when for example a missile/s is/are fired from an SPAA at a helicopter, and at the same time another IR guided missile is fired from different direction by lets say an Airplane, or for example when two independent SPAA systems (for example located at different spawns and firing from vastly different bearing) engage the helicopter simultaneously.

Sources and reading materials on the topic:
https://www.researchgate.net/publication/284156197_Requirements_for_laser_countermeasures_against_imaging_seekers

document.pdf

Requirements For Laser Countermeasures Against Imaging Seekers | PDF | Optics...

[tripod2008]

@Big_Djck_Sergey

If you take 1 mrad Divergence as an example, a beam would grow by about 1 mm per meter of travel — over 1000 m that’s roughly 1 m across. Increase divergence to 5 mrad, and that spot becomes ~5 m wide at 1 km.

And what does that do to the average power per unit area, that jamming critically relies on? and based off the President-S effective ranges vary from 5,000 though 500 meters.

Of which the total energy of the system is 3500 kVA, or if we substitute the values for the CIRCM, average power is 200 watts, and Peak draw is 250 is delivered to the target.

Also it completely ignores the potential change in effected cross section (at the missile’s fixed optical aperture) of having a Focusing mechanism and having the Focal length wrong ( info is not perfect, and pointing error occurs)

[CollectorOfSins]

@Big_Djck_Sergey

In terms of LDIRCM systems, they usually have Beam Divergence from 0.1 to 5 milliRadians.

It’s actually more of 0.1-1 miliRadians.

@Big_Djck_Sergey

Bottom line is:
Assuming such systems are modelled realistically ingame, we would often see situations where DIRCM/LDIRCM would be overwhelmed only in rare cases when for example a missile/s is/are fired from an SPAA at a helicopter, and at the same time another IR guided missile is fired from different direction by lets say an Airplane

Yes you are right

@Big_Djck_Sergey

or for example when two independent SPAA systems (for example located at different spawns and firing from vastly different bearing) engage the helicopter simultaneously.

I would disagree with this, I think two SPAA firing at one side of the heli should not be able to be taken down with one laser as their trajectory will not be the same and the laser should only be able to take down multiple missiles if they came from the same SPAA and both the SPAA and Heli are not moving. Once the Heli moves or SPAA shoots from a different launcher, the trajectory of the missiles will diverge enough to not be defeated by one laser.

Now Gaijin should make the IRIS-T more resistant to DIRCM so I can shoot down those annoying little buggers.

[Sean74218]

Are you telling me that this is accurate?

[Armen_Lozone]

while your initial argument is sound you literally REEK of missing the point.

the common rant on this forum ISNT that a DIRCM shouldnt be able to affect multiple missiles within its FOV, but rather that a DIRCM shouldnt be able to affect multiple missiles within its ENTIRE FoR. Field of regard takes into account the turrets physical motion limits and the FOV of the DIRCM emitter/reflector.

so… you did all that for nothing

oh and need i mention…
with every single photon of divergence… the power of the laser trasnmitted to a target seeker is reduced.
thats one of the reasons why Blooming occurs. its not a single solid color.
but rather a gradient.

NOT TO MENTION IIR seekers are incredibly immune vs DIRLCM

[CollectorOfSins]

Lol if only Gaijin actually cared abut accuracy

[Big_Djck_Sergey]

Replying to Sean74218
If you look carefuly at the video you will see that all the missiles are following basically the same trajectory. Meaning it is possible for the LDIRCM to affect all of them, depending on its Beam Divergence.

That is why it is important to know all parameters of the system in order to be able to take everything into account when modelling it ingame.

[Big_Djck_Sergey]

@Armen_Lozone
Armen, at the moment the game does not simulate LDIRCM as it works in real life. The developers have explained this explicitly multiple times in the public domain. That is why at the moment, as you said, it is “affecting missiles with its entire FOV”

Note: the term FOV is used improperly, the correct term would be FOR - Field of Regard.

Field of Regard (FOR) is the total area the turret can cover by slewing/rotating.

“NOT TO MENTION IIR seekers are incredibly immune vs DIRLCM”

Wrong. An IIR seeker cannot process data if it has no valid image to use. Meaning: if the seeker is blinded or dazzled it will have no input image at all, or have input image without the necessary information to sample and process in order to be used as guidance data.

This is especially true for missiles fired by the IRIS-T: since the missile has no initial information on the shape, size and thermal signature of the data. The missile seeker’s capabilty to even take an initial image of the target can be denied before the seeker is even activated.

In detail bellow:
How IRIS-T’s IIR Seeker Works

1)The missile is typically launched with no prior image of the target.
2)Its Imaging Infrared (IIR) seeker is enabled only after launch, when it is within a certain acquisition range.
3)At that point, the missile begins to form a thermal image of the target and track it.

So initially, the missile does not know the target’s size, shape, or IR signature.

If the Missile’s seeker is Dazzled or Blinded before it could even take an initial sample image of the target,meaning before Step 3, then the IIR guidance of the missile is effectively supressed.

[Big_Djck_Sergey]

So many words, so many sentences, and not a single source of data.

Modern airborne DIRCM/LDIRCM sources are typically 10W ~100W optical output per head in the relevant IR bands (SWIR/MWIR).

Source:
https://aaltodoc.aalto.fi/bitstreams/3fca737e-244d-429f-be09-80a400bfdf26/download

Helsinki University of Technology
Department of Electrical and Communications Engineering
Applied Electronics Laboratory

And another reading material: 红外对抗：各类飞机定向红外对抗综述

[tripod2008]

@Big_Djck_Sergey

not a single source of data

Volume 7 of the Infrared Handbook, 3.3.5.1 Detector Damage

common-infrared-countermeasures-circm-datasheet.pdf

[BeautifulTai_wan]

@Big_Djck_Sergey

If the Missile’s seeker is Dazzled or Blinded before it could even take an initial sample image of the target,meaning before Step 3, then the IIR guidance of the missile is effectively supressed.

IRIS-T and pretty much all other IIR missiles have HOJ capability that will lead them directly along the path of the LDIRCM beam into the target. There’s no reality where LDIRCM beats IIR without becoming a DEW that can actually put holes in missile skin from decent distance.

[tripod2008]

Also with a 2 way datalink, some missiles can straight up ignore the seeker’s output wholesale and still complete an intercept.

[Big_Djck_Sergey]

The thing is, the Seeker does not see the Laser Beam as few pixels in a high quality, high contrast image.

When large area of the Seeker is Dazzled or Blinded, the whole image becomes a high-brightness mess or even blank image, therefore no valid guidance data can be processed out of it.
You dont have a dark image with a bright spot (the presumed laser beam) into it to guide on.
Your whole image is a blank and bright and you have no data to use.

That is exactly the reason why LDIRCM was developed: to ensure full disruption of the image.

[tripod2008]

@Big_Djck_Sergey

When large area of the Seeker is Dazzled or Blinded, the whole image becomes a high-brightness mess or even blank image, therefore no valid guidance data can be processed out of it.

No. you can most definitely get the Gradient back. If it was actually that bright you would have the sun shade activate or be a DEW class emitter not an IR jammer.

@Sandwich1776

Jammers abuse aspects of the Guidance methodology to break the optical lock

[Big_Djck_Sergey]

Jammers abuse aspects of the Guidance methodology to break the optical lock

That is not the case for LDIRCM. As I said it before, the main idea behind LDIRCM is to completely blind the missile’s seeker, so that no useful data can be extracted and processed out of the image.

You are mistaking modern LDIRCM for earlier DIRCM systems.

Edit: even the sources you provided explain that the Seeker itself or even the dome’s surface can be permanently damaged.

Also bear in mind that the book you provided is from 1993. In that period LDIRCM was in early stages of research and development, and no LDIRCM systems were officially adopted in any country.

[tripod2008]

@Big_Djck_Sergey

even the sources you provided explain that the Seeker itself or even the dome’s surface can be permanently damaged

How much energy does it require? It’s well outside of what a L-DIRCM jammer is rated for, let alone what a Helicopter could spare for it’s onboard electronics.

Remember the President-S for example is only rated for 3.5 kVA.

@Big_Djck_Sergey

Also bear in mind that the book you provided is from 1993. In that period LDIRCM was in early stages of research and development, and no LDIRCM systems were officially adopted in any country

Physics do not change suddenly or the mechanics behind a Threat system alter all to much.

you aren’t suddenly increasing performance by an order of magnitude. And if you are that’s a DEW, not a Jammer.

[Big_Djck_Sergey]

The fancy words you put to it don’t really matter. Jammer, countermeasure, call it how you like.

What matters is how it works, and why it was designed in the first place. Conventional DIRCM was not enough to deter modern IR and IIR missiles.
Creating false target Silhouettes, Shapes, at different places around the target, emitting pulsating IR signatures in order to achieve an oscilated or dithered Target Centroid that constantly shifts along the image, and therefore generates oscilating steering outputs was simply not enough, since modern missiles can analyze the image in real time and ignore such areas of the image to keep the Centroid steady.

Therefore a completely different approach was needed: complete occlusion of the Seeker’s sensor. Blind it, flash it, burn it if you want to, its ability to capture and process image has to be affected in order to achieve the desired result.

[Jεcka]

@Big_Djck_Sergey

Conventional DIRCM was not enough to deter modern IR and IIR missiles.

Neither is LDIRCM and Gaijin’s implementation is complete fantasy.

Meaning even though the LDIRCM system is trying to blind only the first missile from said salvo, the rest of the missiles can also be involuntarily blinded by the laser beam, due to its Divergence. This is especially true for scenarios where both the launcher and the helicopter are stationary in space.

Total power output is spread across the whole beam, if the beam expand that much, the amount that hits the seeker will lower and thus be unable to do anything…

[tripod2008]

@Big_Djck_Sergey

Conventional DIRCM was not enough to deter modern IR and IIR missiles.

Yes, because if you look at the ALQ-144A(V), it’s an all analog system that use two spinning interrupters to impart the proper waveform to an incoherent Arc source that is projected broadly into the scene.

So it’s very energy inefficient, and is a Passive system and is always emitting which is very bad for IR signature reduction (RAH-66 used bays to hide it like the F-22 and it’s Sidewinder bay).

This eats up a huge portion of the energy budget, let alone the wasted energy radiated into space.

Laser based systems are much more energy efficient, are Actively cued by the MAWS, and have an extended range due to being carefully directed in an actually useful direction.

They still use the same defeat mechanisms, though being properly digital there’s more that can be achieved, and with the potential for full identification of the threat a specific waveform could be generated tailored to defeating it instead of needing to cycle though generically effective waveforms.

[Big_Djck_Sergey]

The ALQ-144A(V) has NOTHING to do with modern DIRCM or LDIRCM systems that we are discussing in this topic.
It is first-generation omnidirectional IR jammer, and it only works against first generation pin-scan or conical-scan reticle seekers.

And no, laser based systems do not use the same defeat mechanisms. You need to learn the basics before diving in the deep. Laser based systems do not
-rely on injection of false temporal modulation signal into the seeker, (like 1st generation systems)
-Create a false spatial hotspot in space around the helicopter

They:
-Project a directed spot
-Shift the perceived centroid position (depending on seeker’s algorithm sophistication)

Additionally the laser can completely Blind or dazzle the seeker making the image unusable.

It does not require micron-level precision painting upon the seeker. It requires maintaining sufficient irradiance within the seeker’s instantaneous Field of View.
Which is understandable, since it would be impossible to precisely move a tiny beam upon the seeker’s internal focal plane array, while both the missile and the aircraft are moving relative to each other.