Ghost Returns on RWR

Frequently when I look at the RWR/TEWS, I see AI radar on there from a single aircraft, and then if I turn hard, say, to beam him, the return shows two indicators as if he just multiplied. Also, sometimes he will flip to the other side of the display, then back to where he was originally.

Is this because of where the RWR antennae are and my maneuvering is making them see the threat differently? It gets kinda dicey when I am trying to beam a missile or locking aircraft and suddenly I don't know in which direction the threat is coming from based on the RWR.

v6,

boNes

This is the RWR trying to make sense of the signals and correlate all the signals to the same symbol/threat. When you turn it is possible to momentarily confuse the system and additionally the F-14 has the two rearward quadrants mounted on the stabilators. As those can move quickly when you maneuvre that also adds to the issue.

All this is modelled and is the reason for the issue you are describing but it is working as intended.

This correlation system also means that sometimes the RWR can't tell how many of the given threat is present if they're closely packed.

OK, that's what I thought...and one of the things I love about this great sim you have done for us, the attention to detail is austounding!

Thanks!

v6,

boNes

Thanks! :-)

Hey Bones, I thought I'll copy over this description, which will help you understand the RWR a bit better maybe:

A short summery of the difference between our RWR and the default RWR (like found in the F15), could be put like this (quoted from Grover):

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 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 manoeuvres;

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°.

In short:

- 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.

Thanks to Grover for the write up and I hope it helps to get a better idea of our RWR.

PS: 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.

And 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 he is.

So very interesting, and I have noticed alot of this phenomena. Thanks!

v6,

boNes