How does RWR know friendly radars from enemy radars?

[WelshZeCorgi]

It seems to me that the RWR is able to filter out friendly radars, as I never seem to see friendly radars unless the RWR is set to friendly or a friendly is locking or firing a missile at me. In servers that have F14 on both sides, the RWR seems to understand which f14 radars are enemy and which f14 radars are hostile, as I seem to only get warnings when enemy 14s ping me but none when friendly 14s ping me. 

So how does this work? Anyone know?

[Repth]

From my understanding of a similar thread it is basically coded into the sim as a logic check or query from the offending aircraft. @Naquaii could probably explain it better though.

 

Basically it looks for code from the other aircraft. 

 

is entity same coalition?

Is entity(aircraft/radar type)?

is entity transmitting?

what direction is entity?

is self in entity radar cone?

display symbol y/n

 

I'm sure it's probably more complicated than that. I'm no coder, but that was what I got from it.

 

Edited March 17, 2021 by Repth

[Super Grover]

DCS offers ability to mission creators to shape the coalitions to their needs. For example, it means that an F/A-18 from USA can fly against a Canadian F/A-18. From the electromagnetic signal point of view, it's impossible to distinguish between the two, so we decided to use the following procedure:

1. We check the mission content. For each known emitter type, we record the countries (sides) which have at least one unit of this type in the mission.

2. In the second step, we create a custom threat library for this mission. If a given type is present only in the friendly forces, the type is marked as friendly.

3. When an EM signal from a known emitter is registered, it is compared with the threat library. If a given type is known as friendly, it will be displayed only when locking you or when the RWR is set to prioritise friendly emitters. If a type is not registered friendly, it is always displayed using normal prioritisation rules.

 

Let me explain it on an example.

Mission A: US F-14 vs Iran MiG-29 (only those types are present). All F-14 will be treated as friendly.
Mission B: US F-14 vs Iran MiG-29 and Iran F-14. All F-14 will be considered as potentially hostile and all F-14 will be always present on the RWR display.

 

This way we try emulating threat libraries prepared and uploaded to the RWR based on the current geopolitical/theatre of operation situation.

Edited March 17, 2021 by Super Grover

[QuiGon]

12 hours ago, Super Grover said:

DCS offers ability to mission creators to shape the coalitions to their needs. For example, it means that an F/A-18 from USA can fly against a Canadian F/A-18. From the electromagnetic signal point of view, it's impossible to distinguish between the two, so we decided to use the following procedure:

1. We check the mission content. For each known emitter type, we record the countries (sides) which have at least one unit of this type in the mission.

2. In the second step, we create a custom threat library for this mission. If a given type is present only in the friendly forces, the type is marked as friendly.

3. When an EM signal from a known emitter is registered, it is compared with the threat library. If a given type is known as friendly, it will be displayed only when locking you or when the RWR is set to prioritise friendly emitters. If a type is not registered friendly, it is always displayed using normal prioritisation rules.

 

Let me explain it on an example.

Mission A: US F-14 vs Iran MiG-29 (only those types are present). All F-14 will be treated as friendly.
Mission B: US F-14 vs Iran MiG-29 and Iran F-14. All F-14 will be considered as potentially hostile and all F-14 will be always present on the RWR display.

 

This way we try emulating threat libraries prepared and uploaded to the RWR based on the current geopolitical/theatre of operation situation.

 

 

I really like this solution! Thanks for the insight!

(When I was reading through the first few comments of this thread I was afraid to stumble on another unrealistic DCS simplification, so I'm very delighted to see that this is not the case here at all!)

Edited March 18, 2021 by QuiGon

[IronMike]

On 3/17/2021 at 4:45 PM, Repth said:

From my understanding of a similar thread it is basically coded into the sim as a logic check or query from the offending aircraft. @Naquaii could probably explain it better though.

 

Basically it looks for code from the other aircraft. 

 

is entity same coalition?

Is entity(aircraft/radar type)?

is entity transmitting?

what direction is entity?

is self in entity radar cone?

display symbol y/n

 

I'm sure it's probably more complicated than that. I'm no coder, but that was what I got from it.

 

 

 

 

There is a couple of other misunderstandings in this, and so I shall share a write up @Super Grover did a while ago, to give you a better understanding, how the RWR works principally, off topic or beyond the initial question asked. Grover is always too modest to admit it, but it is one of the best and most realistic implementations of RWRs in any sim to date, I would say, and since he did it I am not pumping my chest by saying this , so here it goes:
 

The procedures/logic:

 

- Four sensors/antennas for the radar bands of tracking radars and airborne radars.

 

- Each antenna FOV is ~180° (or slightly more), and almost a perfect cone.

 

- The sensitivity at the edges of the cone is significantly lower than in the centre.

 

- When we get a message from DCS about being radiated, we simulate the signal it produces in each sensor. This includes factors such as the distance from the emitter (attenuation), the angle of arrival for each antenna, noise and other random signal amplitude fluctuations.

 

- From this moment we treat the signal as if we didn't know about the true parameters of the emitter and we only use the information from the emulated sensors (the previous step).

 

- We take the amplitude of the signal from each sensor, apply signal to noise cuts, combine and reconstruct the threat direction.

 

- Then, the reconstructed direction together with the signal signature is compared with the list of threats already being displayed. If we find one that correlates, we update its direction. Otherwise, we create a new threat and inform about it with the 'new guy' sound.

 

Some consequences of the procedure described above and a bunch of other features:

 

- No blind spots. However, if directly above or below, the threat has to be significantly closer (compared to the horizontal plane) to pass the SNR threshold.

 

- The direction is reconstructed in the 2D plane (the local aircraft frame of reference). For threats significantly outside that plane, their reconstructed direction may be inaccurate, and it usually shifts towards the 12, 3, 6, or 9 o'clock from the true position.

 

- The direction reconstruction accuracy improves as the distance from the emitter decreases. For the scan modes of the emitter (RWS/TWS), it's somewhere around 10-15° RMS.

 

- For the emitters in scan modes, a misassociation of a known-threat with a new signal can happen, and it occurs quite often, especially at long ranges. It can result in:

a) ghosts (fake threats) appearing on the display - more probable if you or the threat do some maneuvres;

b) merging a group of two or more threats of the same type into one threat. For example, a group of two Su-27 flying in close formation, both scanning with their radars, can appear on the screen as one '29' until they get closer.

 

- A malfunction/damage of one antenna/sensor doesn't make you completely blind in that direction, as the two adjacent antennas should still cover that area. However, the lack of that sensor makes the direction reconstruction procedure very innacurate, and it's very likely that some threats will be displaced by more than 90°.

 

Compared with the default RWR from DCS:

 

- An entirely new dedicated code, written from the grounds up.

 

- Antenna/electronics emulation.

 

- Threat reconstruction using the emulated signals.

 

- Enhance information obtained from the engine with more details (radar modes, missile guidance, noise etc.).

 

- No blind spots.

 

- Imperfect like a real device should be, and not a god's eye:

a) Some weak radars can appear late.

b) The directions will be inaccurate.

c) It will be harder to estimate the number of threats of one type when they form a group.

d) You'll receive launch warnings not only when you are the target of the missile. For example when flying in a close formation with your buddy; if an enemy launches a weapon such as AIM-7 or SA-6 at your buddy, you may receive a launch warning from that threat as well.

 

- Detailed failures/damages.

 

Another thing to consider with the RWR is that the antennas move with the control surfaces, which means that this will roll your RWR picture, just as when you are maneuvering the aicraft, the RWR picture will roll with it. This requires additional pilot skill to take RWR readings at the proper (level) moment in the maneuver in order to keep up an accurate SA as well as an eye to spot wrong readings in between. By roll I mean it will flip not only the bearing of your RWR contact, but will additionally produce erronous readings as mentioned by Grover above, for example the displacment out of the plane will move them to the 12,6,3,9 positions but also duplicate them, or in some cases even quadruple them, so that 1 single contact could be displayed on all 4 positions. it is very important thus to note the true heading vector to the target before breaking into a maneuver, too, or you might not know where and when a roll out for a new reading would be best (ideally a mix of offensive firing position, defensive crank or offset for evasive maneuvers and level for a new rwr reading).

 

 

I hope this helps a bit to understand how the RWR works and how it has been created.

Edited March 19, 2021 by IronMike

[Repth]

@Super Grover  @IronMike Thank you both for those tidbits of information. Always eager to learn. 

[Csgo GE oh yeah]

So how does this work in laymans terms ?
How does the F14 RWR distinguish a friendly aircraft from an enemy aircraft in a multiplayer server where some aircraft are in both sides ?? 

[Naquaii]

1 minute ago, Csgo GE oh yeah said:

So how does this work in laymans terms ?
How does the F14 RWR distinguish a friendly aircraft from an enemy aircraft in a multiplayer server where some aircraft are in both sides ?? 

 

When loading up the module the rwr code marks all aircraft radars only existing as friendlies as such as that's how a threat library for an RWR would be constructed IRL.

 

So if you have a mission with hornets only on one side, an F-14 on that side would see them as friendlies. If you then open the mission editor and add hornets to the other side as well the rwr in the F-14 will then not mark them as friendlies as it would then see that they exist on both sides.