reported F16 Look Down

[Hobel]

F16 sees F16 at the same height from ~41nm in the test  50kft

but if one F16 is at 60k ft it can only see another F16 at 50k ft from ~26nm onwards.

Is this an intentional behaviour at such heights?

The whole thing goes like this, If you are 10k ft below an F16, it can only lock you on from 26nm.

F16 look down 60vs50ft ~26nm.trkF16 look down 50vs50ft ~41nm.trk

 

Edited July 21, 2022 by Hobel

[BIGNEWY]

Hi 

With a 30k split in altitude, I see the target at 30 nm, not 26. This is correct based on the very limited data and SME feedback.

In these images, I am at 50k and the target at 30k

bugged/designated at 29 nm. before the update today it was 22 nm

This is correct based on available references.

[_SteelFalcon_]

I tested a scenario, me at 40 000, enemy at 20 000

could only detect and lock at 26nm as can be seen in the track

EDIT: Both planes are F-16s

Look down.trk

Edited July 21, 2022 by _SteelFalcon_

[Comrade Doge]

3 minutes ago, BIGNEWY said:

Hi 

With a 30k split in altitude, I see the target at 30 nm, not 26. This is correct based on the very limited data and SME feedback.

In these images, I am at 50k and the target at 30k

This is correct based on available references.

Two main things I'd like to ask:

1. During my testing, me at 40k ft can detect a target flying at 30k ft, at about 30nm. The same target flying at 5k ft will still be detected at the same range. Is it normal for the look-down penalty to be fixed, regardless of the antenna angle?

2. Wags told us in a Viper mini update this: "It is now possible to have a valid track on a look-down target (MiG-29) more than 30 nm." However, this proves impossible at the moment.

We are eagerly waiting for more details...

[BIGNEWY]

2 minutes ago, Comrade Doge said:

2. Wags told us in a Viper mini update this: "It is now possible to have a valid track on a look-down target (MiG-29) more than 30 nm." However, this proves impossible at the moment.

Added to the above post about bugging the target at 29nm, almost 30 nm just off by 1 nm, it also greatly depends on aircraft RCS and Vc 

[Comrade Doge]

5 minutes ago, BIGNEWY said:

Added to the above post about bugging the target at 29nm, almost 30 nm just off by 1 nm, it also greatly depends on aircraft RCS and Vc 

Indeed that concurs with my research as well, in look-down, the bugging range currently sits at about 29nm. I was expecting a bit more above 30nm, but as you said, it depends on closing velocity.

About point 1 though, you will observe that 29nm lock range is identical regardless of the difference in elevation with the target. Be it 10k ft below you or 40k ft below you, it is the same range penalty. Most curious detail, we'd appreciate a word to clear it up if that's possible...

Edited July 21, 2022 by Comrade Doge

[BIGNEWY]

Based on available references, we have no evidence that it should be different. As always, we are open to actual contrary evidence and not second hand accounts and theories. 

thank you

[Hobel]

vor 20 Minuten schrieb BIGNEWY:

Based on available references, we have no evidence that it should be different. As always, we are open to actual contrary evidence and not second hand accounts and theories. 

thank you

I think they are trying to simulate radars and not just set fixed values?

 

in this example, the F16 on 60kft can only build up a lock on 26nm

the F16 at 50k ft already at 40nm!

that is a difference of 14nm...

Maybe someone here knows better and can explain to us why the example shown is correct.

[NineLine]

37 minutes ago, Hobel said:

I think they are trying to simulate radars and not just set fixed values?

 

in this example, the F16 on 60kft can only build up a lock on 26nm

the F16 at 50k ft already at 40nm!

that is a difference of 14nm...

Maybe someone here knows better and can explain to us why the example shown is correct.

Yes, because the example at 60k is in look down, where as at 50k there is virtually no look down, unless we are not understanding your point. 

[NineLine]

Guys, I appreciate you all wanting to try and help make DCS better, but please please please read the rules. If you have questions about 1.16 or 1.3, please message me and/or BIGNEWY. All of you posting here have been here long enough to know these rules though.

Because a document has been posted elsewhere on the forums doesnt mean its ok to post. It means the other post hasnt been cleaned yet.

The 1.16 in question is hardly a document worthy of coding a complex radar system on either, its a sales pitch for why the F-15 is better than what the US had at the time. Also we already have the document. 

Please try and respect the rules when posting. 

[Geraki]

Please make some TestCases in order to help in development.  be in mind it is simulated the APG-68v5 Radar version max solid lock (is supposed to have a range of 35-40NM (≙ 65-70 km) in the “look-up” mode and 27.5 -33NM (≙ 50-60 km) in the “look-down” mode. The APG-68(V)9 radar has a 30% greater air-to-air detection range (i.e.: 53 NM 85 km)

Start from e.g F-16 vs f-16 same RCS   , F-16 Vs different RCS 

1. 60K and 50k 50 miles target.   long-long senarios  low level split

2  60k and 20k 30 miles target  long-short secarios high level split

3. 15k and 3k target 20 miles seperation look down radar solid lock?  low-low  low level split

 

 

 

 

[Hobel]

vor 22 Stunden schrieb NineLine:

Yes, because the example at 60k is in look down, where as at 50k there is virtually no look down, unless we are not understanding your point. 

what kind of look down? The radar only reaches the ground when it is +160nm behind it, why is this still a factor at such heights? 

Edit:On the other hand, if the aircraft is 6000ft high and the target 5000ft you can look 40nm, although here is much more potential for ground clutter and the radar hits the ground much earlier, that is a contradiction in terms. And this is not the only one here

The look down in the scenario as it is in DCS would make much more sense at low altitudes but not like this.

 

  it wouldn't change anything if i set the plane to 500,00ft and the target to 499,990 ft, would that still be "look down" argument? 

A fixed value has been set here that makes sense in certain scenarios, but also causes undesirable side effects.   

  we can lock on a target  at 40nm, 10k ft less at an altitude that is still far away from ground clutter do we once have a malus of 14nm?  i am really curious about the explanation

Edited July 22, 2022 by Hobel

[Noctrach]

@BIGNEWY@NineLine

I am curious however how it's possible that flying at 50,000 feet over sea causes enough of a drop in signal to noise ratio for a target flying at 40,000 feet to reduce detection range by 25%, while simultaneously still having the TWS range and azimuth resolution to perfectly discriminate an F-16 flying close formation in the radar shadow of a B52.

My follow-up question would be why the same exact values apply for 50,000 -> 1000 feet over land (contact within mainlobe clutter) as for 50,000 -> 40,000 feet over sea (contact well outside mainlobe clutter).

 

Things like this make it seem like the DCS AN/APG-68v5 radar simulation isn't actually taking into account any kind of mainlobe clutter or doppler binning, but rather looking for game-objects within flat, hardcoded parameters.

OddlyAccurateRangeResolution.trk

Edited July 22, 2022 by Noctrach

[Hobel]

vor 2 Minuten schrieb Noctrach:

@BIGNEWY@NineLine

I am curious however how it's possible that flying at 50,000 feet over sea causes enough of a drop in signal to noise ratio for a target flying at 40,000 feet to reduce detection range by 25%, while simultaneously still having the TWS range and azimuth resolution to perfectly discriminate an F-16 flying close formation in the radar shadow of a B52.

My follow-up question would be why the same exact values apply for 50,000 -> 1000 feet over land (contact within mainlobe clutter) as for 50,000 -> 40,000 feet over sea (contact well outside mainlobe clutter).

null

 

Things like this make it seem like the DCS AN/APG-68v5 radar simulation isn't actually taking into account any kind of mainlobe clutter or doppler binning, but rather looking for game-objects within flat, hardcoded parameters.

OddlyAccurateRangeResolution.trk 45.55 kB · 0 Downloads

Small note I have always tested 10,000ft difference. 

The same probably happens even if the difference is only 4000ft...

  But I have to look at this again more closely

[_SteelFalcon_]

47 minutes ago, Hobel said:

Small note I have always tested 10,000ft difference. 

The same probably happens even if the difference is only 4000ft...

  But I have to look at this again more closely

I did some tests. following setup:
bandit F16 at 30k ft, hot, set to "do nothing". see test.miz

i then adjusted my own spawn, starting at 31k ft and increasing in increments of 1000 ft each time and observed at what range the radar detects the target.
from 31k up to 37k ft, the detection was at about 42nm, possible to bug the bandit at about 39nm as advertised.
 

Then i tested 38k ft. and i hit a brick wall so to speak. suddenly i can only detect the bandit at 30nm, bug possible at constantly 26.5nm roughly.
so 1000ft lost me 10+nm. no gradual decline, just instant.
 

i ran it again, starting at 38k ft just to confirm. same result

then i ran the 37k ft test again, waited til radar detected the bandit, instantly pulled up to 38k ft and i lost him quick. he only reappeared at 30nm, bug at 26.5nm.

no gradual decline. instant drop off of 10+nm range

 

MIZ here, just change your own altitude to run the tests.

results in zip below too

i don't know if that is correct behavior, it does seem odd however.

If someone wants to test other altitude blocks to see where you hit that wall with the 10+nm instant drop off, feel free

test.miz Radar Tests.zip

Edited July 22, 2022 by _SteelFalcon_

[TheBigTatanka]

Probably related to this bug, if you lock a contact co-altitude at a range of ~40nm, and continue to climb in your commit, the radar will lose lock when you get ~10k above the bandit, and they vanish from the FCR until you get much closer.

It's awesome that the lock range vs detection range took a step towards realism, but the look-down modeling is either borked or WIP. I think as others have noted, it doesn't seem to actually model the interference of mainlobe and sidelobe clutter (or the tools to combat that interference); and instead applies a generic formula.

As others have said, look-down penalty should, in most cases, only be a problem when the fighter is at low altitude. I've also been told that the look-down problem would manifest itself more like extra contacts appearing on the radar -- which is why you wait for two target histories before trying to lock (as a technique).

Of course, ED isn't interested in second hand accounts.

Sent from my Pixel 3 XL using Tapatalk

[Tango3B]

7 hours ago, Noctrach said:

@BIGNEWY@NineLine

I am curious however how it's possible that flying at 50,000 feet over sea causes enough of a drop in signal to noise ratio for a target flying at 40,000 feet to reduce detection range by 25%, while simultaneously still having the TWS range and azimuth resolution to perfectly discriminate an F-16 flying close formation in the radar shadow of a B52.

My follow-up question would be why the same exact values apply for 50,000 -> 1000 feet over land (contact within mainlobe clutter) as for 50,000 -> 40,000 feet over sea (contact well outside mainlobe clutter).

 

Things like this make it seem like the DCS AN/APG-68v5 radar simulation isn't actually taking into account any kind of mainlobe clutter or doppler binning, but rather looking for game-objects within flat, hardcoded parameters.

OddlyAccurateRangeResolution.trk 45.55 kB · 1 download

 

And exactly this is my problem with the current implementation of the APG-68v5. These scenarios are simply illogical and against every form of radar theory which can be found in an academic context about newer radar systems. Since my last post got deleted for apparently quoting Hobel´s statement including that infamous document I still want to see ED´s white paper. We were promised to see how ED implements radar techology and how ED justifies these measures that currently affect the APG-68. I think at this point it would only be fair to have a better understanding of ED´s train of thought. I think there is no breach of any rule in this post and I want to politely ask for an ETA on the above mentioned white paper. Thanks.

[NineLine]

Just a heads up, there is a discussion going on about this still, the report has not been closed on this yet, so before we get insulting, argumentative and post things we regret, understand that this is not the final integration, and its possible changes will be made.

I will leave this open if you have something constructive and helpful to say, but pure opinion will not help. Thanks.

[GGTharos]

@NineLine I think this is an issue of simplification.   There is geometry involved, where eg. look-down may not actually be look-down due to the curvature of the earth, as well as the type of background clutter present.  Similarly, there exist look-up that would give you 'look-down' results, ie. a SAM (or low flying aircraft) looking up at the side of a mountain.

DCS does not cover these scenarios because instead of attempting to compute SNR and other actionable attributes (all knowledge which is readily available to anyone and known by ED, including various equations to calculate these things), it attempts to simplify them into antenna slew down vs antenna slew up.

That is the impression that the current situation gives, I figure Maestro should be able to clear this up.

[okopanja]

53 minutes ago, GGTharos said:

There is geometry involved, where eg. look-down may not actually be look-down due to the curvature of the earth, as well as the type of background clutter present.

What did you mean by this?

Can you please sketch a diagram of this geometry?

[GGTharos]

PDF page 8 or 15 depending on what you use to determine the page number.

Not the most appropriate thing but close enough.

 

Edit:  Forgot to paste the link in.

 

https://apps.dtic.mil/sti/pdfs/AD1128253.pdf

Edited July 26, 2022 by GGTharos

[Mr. Wilson]

18.06.22 I've done radar tests, task of the test is to determine the dependence of the detection and lock range on the altitude of the target.

24.07.22 re-testing was carried out related to the last patch in order to understand how the radar has changed again, it should be noted that all tests were carried out under the same conditions.

 

18.06.22

Test conditions:

The two jets converge face to face at different altitudes. Attack aircraft F16 target aircraft also F16.  FCR mode - RWS (SAM).

Result:

CASE 1 -- Fighter h=1 000 ft / Target h=1 000 ft / Detection range=13 nm / Lock=11.6 nm

CASE 2 -- Fighter h=1 000 ft / Target h=5 000 ft / Detection range=14.2 nm / Lock=11.6 nm

CASE 3 -- Fighter h=1 000 ft / Target h=10 000 ft / Detection range=14.4 nm / Lock=12.3 nm

CASE 4 -- Fighter h=1 000 ft / Target h=20 000 ft / Detection range=13.7 nm / Lock=11.3 nm

CASE 5 -- Fighter h=1 000 ft / Target h=30 000 ft / Detection range=13.2 nm / Lock=11.8 nm

CASE 6 -- Fighter h=30 000 ft / Target h=1 000 ft / Detection range=26.5 nm / Lock=22.7 nm

CASE 7 -- Fighter h=20 000 ft / Target h=1 000 ft / Detection range=26.7 nm / Lock=23 nm

CASE 8 -- Fighter h=10 000 ft / Target h=1 000 ft / Detection range=27.8 nm / Lock=23.6 nm

CASE 9 -- Fighter h=5 000 ft / Target h=1 000 ft / Detection range=27.1 nm / Lock=22.6 nm

CASE 10 - Fighter h=20 000 ft / Target h=20 000 ft / Detection range=41.8 nm / Lock=35.7 nm

CASE 11 - Fighter h=10 000 ft / Target h=20 000 ft / Detection range=37.65 nm / Lock=32.3 nm

CASE 12 - Fighter h=20 000 ft / Target h=10 000 ft / Detection range=27.85 nm / Lock=23.6 nm

CASE 13 - Fighter h=20 000 ft / Target h=30 000 ft / Detection range=38.5 nm / Lock=32.5 nm

CASE 14 - Fighter h=30 000 ft / Target h=20 000 ft / Detection range=27.1 nm / Lock=23.2 nm

CASE 15 - Fighter h=5 000 ft / Target h=20 000 ft / Detection range=37 nm / Lock=31 nm

CASE 16 - Fighter h=20 000 ft / Target h=5 000 ft / Detection range=27.92 nm / Lock=23.2 nm

 

24.07.22

Test conditions:

The two jets converge face to face at different altitudes. Attack aircraft F16 target aircraft also F16.  FCR mode - RWS (SAM).

Result:

CASE 1 -- Fighter h=1 000 ft / Target h=1 000 ft / Detection range=14.33 nm / Lock=13.5 nm

CASE 2 -- Fighter h=1 000 ft / Target h=5 000 ft / Detection range=14.35 nm / Lock=13.3 nm

CASE 3 -- Fighter h=1 000 ft / Target h=10 000 ft / Detection range=14.35 nm / Lock=13.3 nm

CASE 4 -- Fighter h=1 000 ft / Target h=20 000 ft / Detection range=14.63 nm / Lock=13.8 nm

CASE 5 -- Fighter h=1 000 ft / Target h=30 000 ft / Detection range=13.22 nm / Lock=12.7 nm

CASE 6 -- Fighter h=30 000 ft / Target h=1 000 ft / Detection range=27.23 nm / Lock=25.9 nm

CASE 7 -- Fighter h=10 000 ft / Target h=1 000 ft / Detection range=27.69 nm / Lock=26.3 nm

CASE 8 -- Fighter h=5 000 ft / Target h=1 000 ft / Detection range=27.76 nm / Lock=26.3 nm

CASE 9 -- Fighter h=20 000 ft / Target h=20 000 ft / Detection range=41.85 nm / Lock=39.2 nm

CASE 10 - Fighter h=10 000 ft / Target h=20 000 ft / Detection range=38.66 nm / Lock=36 nm

CASE 11 - Fighter h=20 000 ft / Target h=10 000 ft / Detection range=27.38 nm / Lock=25.8 nm

CASE 12 - Fighter h=20 000 ft / Target h=30 000 ft / Detection range=38.31 nm / Lock=36.7 nm

CASE 13 - Fighter h=30 000 ft / Target h=20 000 ft / Detection range=27.84 nm / Lock=26.4 nm

CASE 14 - Fighter h=5 000 ft / Target h=20 000 ft / Detection range=38.16 nm / Lock=36.6 nm

CASE 15 - Fighter h=20 000 ft / Target h=5 000 ft / Detection range=27.91 nm / Lock=26.5 nm

As you can see, after the patch, the situation has become somewhat better but in all cases at all altitudes we see a delay between Detection and Lock range, Why ? we did not have such an effect before and on other jets there is no such effect either...

And also very confusing losses in the detection range in CASES 1-5... I believe this is the effect of wave reflection from the ground, but why does it break the detection range so much? perhaps there is an error here?

[BIGNEWY]

Sorry is this a bug report? or just an observation?

please include track replays

 

[okopanja]

7 hours ago, Mr. Wilson said:

we did not have such an effect before and on other jets there is no such effect either...

Your measurement are interesting, but I have to tell you this is simply not true. Lock range is shorter in other aircraft as well.

Edited July 28, 2022 by okopanja

[Moonshine]

sounds like it might be related to the observations made in this bug report: