RWR / Jester picking up launches on other aircraft - Page 2 - ED Forums
 


Notices

Reply
 
Thread Tools Display Modes
Old 03-16-2019, 05:21 AM   #11
IronMike
Member
 
IronMike's Avatar
 
Join Date: Apr 2010
Location: Austria
Posts: 249
Default

Hi guys,

this is not a bug, but simply how realistic RWR works (not talking about the bug where 1 radar triggers lock for everyone, this seems to be a separate issue within DCS and not related to the Tomcat). It only knows there is a launch and it does not know whether this launch is on you or not. That it picks off launches from so far, is due to how these launches are being emitted in DCS: if they paint you, the RWR will respond to it, and with some radars that can be very far.

That other RWRs "know" which launch is on you and which not is rather not realistic. Also note that the F14s RWR coverage does not have dead zones, its inaccuracies come from other reasons.

This is not necessarily in direct reply to your question anymore, but please check out this overview written by our Grover, who designed the RWR:

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 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°.

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 (and might display erronous contacts). 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.

I hope this helps with understanding the RWR better.

Best regards, IronMike
__________________
Heatblur Simulations

Please feel free to contact me anytime, either via PM here, on the forums, or via email through the contact form on our homepage.

http://www.heatblur.com/

https://www.facebook.com/heatblur/

Last edited by IronMike; 03-16-2019 at 05:27 AM.
IronMike is offline   Reply With Quote
Old 03-16-2019, 06:27 AM   #12
Cobra847
3rd Party Developer
 
Cobra847's Avatar
 
Join Date: Sep 2012
Location: Helsingborg, Sweden
Posts: 2,929
Default

Quote:
Originally Posted by backspace340 View Post
Thanks for the tips, but that doesn't solve the bug. That happened because we were miles away from the action and we assumed the bug was triggering again (like it had 50 times before that). It would just be nice to have launch warning = being launched on, like it is in every other module.
IronMike made a good post above that goes into detail. Our simulation is simply deeper and more realistic.

The excessive range is a bug however and being looked at.
__________________
Nicholas Dackard

Founder & Lead Artist
Heatblur Simulations

https://www.facebook.com/heatblur/
Cobra847 is offline   Reply With Quote
Old 03-16-2019, 07:33 AM   #13
metzger
Member
 
Join Date: Feb 2015
Location: Czech Republic
Posts: 663
Default

And how about Jester to be able to somewhat distinguish and not go crazy when the lunch is obviously not at own aircraft ?

Sent from my Redmi 4 using Tapatalk
metzger is offline   Reply With Quote
Old 03-16-2019, 11:52 PM   #14
Sandman1330
Member
 
Join Date: Feb 2015
Location: Alberta, Canada
Posts: 678
Default

This behaviour is realistic for radars in search mode only (nails/dirt).

In STT or launch guide mode, a radar cone is only in the vicinity of 2 degrees wide, +/- a bit depending on the system.

Therefore, everyone should get a nails/dirt/spotted when a search emitter goes active, but only the target or other aircraft in very close proximity to the target should receive STT or launch indications (spiked/mud/singer). This is the long standing DCS bug. At long ranges, the distance will be larger than at close range, but no way an aircraft 40, or even 10, miles away should get the threat indication unless they are directly in line front or back with the tracking beam, or many hundreds of miles away. I’m too lazy to do the trig to figure out what that distance is at 200 miles...
__________________
R5 1600X @ 4Ghz / Asus Crosshair VI Hero X370 / Corsair H110i / EVGA GTX 1080ti FTW3 / 32Gb G.Skill TridentZ 3200 (@2933... for now) / Samsung 960 Evo M.2 / Saitek X56 / Saitek Pro Combat pedals / Rift CV1

Last edited by Sandman1330; 03-16-2019 at 11:55 PM.
Sandman1330 is offline   Reply With Quote
Old 03-17-2019, 03:04 AM   #15
Santi871
Member
 
Santi871's Avatar
 
Join Date: Jan 2015
Posts: 130
Default

Quote:
Originally Posted by Cobra847 View Post
IronMike made a good post above that goes into detail. Our simulation is simply deeper and more realistic.

The excessive range is a bug however and being looked at.
Thanks cobra, I hope you guys manage to fix it soon(tm) as the warnings from across the map can be pretty distracting and confusing. Also, nice simulation and nice writeup ironmike!
__________________
Santi871 is offline   Reply With Quote
Old 03-17-2019, 03:31 AM   #16
microvax
Senior Member
 
Join Date: Mar 2016
Location: Germany
Posts: 1,318
Default

Sidelobes
I agree that DCS exagerates that part a bit but assuming you need to be in the mainlobe to get a RWR detection isnt accurate either.
__________________


*unexpected flight behaviour* Oh shiii*** ! What ? Why ? What is happening ?
microvax is offline   Reply With Quote
Old 03-17-2019, 09:00 PM   #17
Dino Might
Member
 
Dino Might's Avatar
 
Join Date: May 2015
Posts: 668
Default

Awesome writeup, IronMike. That answers all my questions/concerns. I am very pleased the F14 models the RWR more realistically, though I will have to change how I fly, being used to (unrealistically) using the F5 RWR as a passive localization and intercept tool.

I hope the AI radar behavior and consequential launch warnings from 200 nmi away ends up getting resolved. As it is, I am usually ignoring the RWR if I haven't heard Jester calling out bandits within 20 nmi.
Dino Might is offline   Reply With Quote
Old 03-19-2019, 04:29 PM   #18
Super Grover
Junior Member
 
Super Grover's Avatar
 
Join Date: Nov 2010
Posts: 72
Default

If I could clarify it a bit further, and split the problem into two: the range and the geometrical relations (cone in which the radar beam is emitted).

Let's start from the range. There are four antennas on the aircraft receving radar waves. Their sensitivity - and thus the received signal strength - depends on the angle of arrival of the radar wave. The RWR electronics anaylzes the strengths from the antennas, and reconstructs the relative direction of the emitter. As you can see, there's no direct information on the signal emitter distance from the aircraft. It's hidden in the signal strength, but the relation isn't simple. I'll give you two examples when the signal received can be low but the threat real. The emitter can use a low emission mode (even the F-14 has low range, low emission ACM radar modes) and you as the threat won't know about it. The threat may be directly below or above you - because of the antenna type used in the RWR, the signal received from below or above can be very low. All of above makes the RWR unable to calculate the distance from the threat accurately enough to apply hard cuts on the threat distance. It's better to get a few false positive alerts than to get one false negative, and be shot by a missile about which you wasn't warned from the RWR.

The geometrical relations.
The main beam lobe width of a tracking radar can be as large as 10-15 degrees. Plus there are side lobes. The same applies to the missile guidance signal. In DCS, the emitter owner (module) decides which objects are withing the beam geometrical limits, and sends information about being painted by the radar to those objects. Maybe some systems are a bit too generous in informing about being locked, but it's not something we can control.

The real life RWR have limitations, and are less precise than we - the flight simmers - usually imagine them. Our goal was to recreate that realistic, imperfect behaviour, and we want to make it even better. And our next step will be the ALR-45/ALR-50 for the F-14A, which is even more analog and much simpler system.
__________________
Krzysztof Sobczak

Heatblur Simulations
https://www.facebook.com/heatblur/
Super Grover is offline   Reply With Quote
Old 03-20-2019, 02:33 PM   #19
Raven434th
Member
 
Raven434th's Avatar
 
Join Date: Mar 2006
Posts: 365
Default

With all that said...will the RWR code be available to other aircraft in the sim? We can't go on having all this inconsistency from module to module. Things need to be looked at as a whole.(where its applicable of course)
__________________


AMD FX 8350 4.0 Ghz CPU , ATI RX 560 4 gig GPU ,32 gig ram on Win7 64bit.
Raven434th is offline   Reply With Quote
Reply

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump

All times are GMT. The time now is 04:08 AM. vBulletin Skin by ForumMonkeys. Powered by vBulletin®.
Copyright ©2000 - 2019, Jelsoft Enterprises Ltd.