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Radar effectiveness


derodo

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Hi all,

 

I made a quick search and didn't find anything specific on this topic; at least nothing that explains/addresses what I've experienced in 2.5 (and possibly in 1.5; not sure).

 

The thing is, it's been already a few times where I got contacts right in front on me, co-altitude, not beaming, less than 30nm, and the radar is unable to pick them up.

 

I verified antenna elevation, tried changed PRF, but nothing. Until...I switch to close-combat mode (still nothing, they're too far for that), then put radar on stand-by, then back to on again, and voila, the contacts show on the radar.

 

Is anyone experiencing this? It might be just coincidence, but as I said, this has happened to me a several times. Don't know if the radar is *that* bad IRL; I'd say it's not. Goddamit, I even get to spot the contacts visually before they show up on the radar (at least some times); and everytime that happens, I do the trick combat-mode/stand-by/on and the targets show...maybe it's just the way it is, or I simply suck at this (which is probably true too). I'm so confused :(

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... I got contacts right in front on me, co-altitude, not beaming, less than 30nm, and the radar is unable to pick them up.

Tacview is the thing you need to use to see if the missing detection is a DCS bug.

 

The radar will also drop contacts that are co-speed, IIRC there is a radar ground return/echo that travels at the same speed as your aircraft and a filter (+/- 10 knots ?) that filters it out. So remember to check your closure speed.

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Good call Ramsay; Indeed, that could be the case. But then, switching to low/med PRF should make them appear, shouldn't it?

 

It's weird though; because every time that happens, switching to close-combat and then back to VBR always makes the targets show on radar. It might be just coincidence, and maybe it simply works because at that time the closure rate is not zero anymore...but that's suspicious; specially when it happens every time; and some of the times I spend quite a lot of time playing with the radar making sure everything is in place, and it never works until I do the mode switching...

 

I'll take a closer look whenever it happens again, and try to accelerate/decelerate like crazy to see if the targets appear.

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What is the aspect of the target when you can't detect it at 30Nm ?

Hot or cold ?

 

I have tested that in DCS (M-2000C and F-15) we have poor radar range on cold target, especially in HPRF.

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Can’t remember. I’d say it happened in both cases. It definitely was the case for cold targets, since that’s the last time it happened. Need to check again and take good note about it.

 

I understand the radar might not detect the target if cold and close to my speed; but I think it also happened with hot targets. But don’t take my word for it. I’ll come back when I have more detailed info.

 

Anyway, is it recommended to switch to low/mid PRF when chasing cold targets, then? I’m sure I switched modes and waited for a while to see if the contacts showed. No joy until I did the close-combat/stand-by/on trick.

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Well I am no expert but would like to give me opinion. 30nm is a lot of distance. A fighter aircraft's radar is not powerful enough like an awacs. If the boggy is at low altitude, the radar might now be able to detect it due to ground interference. Secondly, cold or flanking aspect also makes it difficult for radar to detect.

 

Only a real fighter pilot can shed some light on how close dcs is to reality when it comes to radar.

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Well I am no expert but would like to give me opinion. 30nm is a lot of distance. A fighter aircraft's radar is not powerful enough like an awacs. If the boggy is at low altitude, the radar might now be able to detect it due to ground interference. Secondly, cold or flanking aspect also makes it difficult for radar to detect.

 

Only a real fighter pilot can shed some light on how close dcs is to reality when it comes to radar.

 

That's all well and good but it also happens at VERY short ranges, like 1-2km at times. I can clearly see my opponent, but my radar can't regardless of PRF mode, regardless of aspect angle and regardless of velocity delta. However flicking the special mode on and off makes it work, suggesting it is actually a bug.

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Had the same during the radar training mission in 2.5.

 

The L-39s were nowhere to be seen. Used f10 and vectored myself to the side and behind and nothing. Ended up getting hundreds of meters behind and still not radar contact..

 

 

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Guys, it’s a real bug. It has nothing to do with aspect or speed of the target or whatever.

Sporadically, it happens that the radar picks up nothing. Then you switch to ACM mode, Reset and scan again and targets appear normally. It’s clearly bug. I have been flying the Mirage from day and I’m very familiar with the radar.

 

 

Sent from my iPhone using Tapatalk

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What is the aspect of the target when you can't detect it at 30Nm ?

Hot or cold ?

 

I have tested that in DCS (M-2000C and F-15) we have poor radar range on cold target, especially in HPRF.

 

 

 

It happens at all ranges. It’s sporadic, and going to ACM and reset solves the issue. It’s a bug.

 

 

Sent from my iPhone using Tapatalk

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It's always the same thing, without a track we can't assess if it's a bug or user error (like radar elevation setting, the closer the more sensitive it is).

Strangely I don't have such bug.

 

IMHO, and based on some radar theory book reading, the radar range in HFR on cold target is too low.


Edited by jojo
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Tail-on range in HPRF is typically quite low compared to head-on and this is correct. You'll need to see radar test data to convince yourself though.

 

You guys have an LPRF mode which should give good performance.

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Tail-on range in HPRF is typically quite low compared to head-on and this is correct. You'll need to see radar test data to convince yourself though.

 

You guys have an LPRF mode which should give good performance.

 

But it isn't this. When the bug occurs, the radar will absolutely refuse to see the target at all under ANY circumstances unless a special mode is selected then deselected; ergo bug.

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I do agree with that. It's also interesting that a reset fixes it. It suggests that there's a runaway variable somewhere and this radar isn't 'looking' where it ought to be looking. Just my guess.

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Tail-on range in HPRF is typically quite low compared to head-on and this is correct. You'll need to see radar test data to convince yourself though.

 

You guys have an LPRF mode which should give good performance.

 

Yep, I don't deny it.

The question is the amount of the difference.

 

I had around -50% in mind for tail Vs head on. But currently we are well below that, including DCS F-15C.

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Jojo,

I have some radar test results for the original (kinda sucky :) ) APG-63v(0), no MSIP, no upgrades.

 

Detection range head-on against T-33 (RCS similar to MiG-21, but not same) is 90nm in HPRF.

Detection range tail-on is 30nm consistently in MPRF. These ranges are probably improved with MSIPII, but this suggests about 1/3HRPF range in MRPF rail-on, and HPRF should be shorter still.

 

Of course, that's for that radar. It's entirely possible that waveform/PRF specifics can make things 'better' for the Mirage in this respect.

 

Yep, I don't deny it.

The question is the amount of the difference.

 

I had around -50% in mind for tail Vs head on. But currently we are well below that, including DCS F-15C.

[sIGPIC][/sIGPIC]

Reminder: SAM = Speed Bump :D

I used to play flight sims like you, but then I took a slammer to the knee - Yoda

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  • 2 months later...

Hi again,

 

I think I've experienced this weird behavior again; I mean...I think it has always been there, but I have a track file this time (or so I think).

 

It's a very simple one; just wait till the second minute (16:22 world mission time) and get to the cockpit view.

 

Radar on, HFR, 20nm range, azimut neutral (in the midle); there's a SU-27 coming hot on me, straight on, co-altiture. Close. Nothing shows up.

 

I can see it in front of me as a black dot; I can even start making its sillouette as it approaches, but the radar showed nothing for entire time until the SU27 just zoomed past me.

 

Maybe it's just me and I'm doing something wrong, or maybe I missed something somewhere...shouldn't that SU27 have showed up at some point on the radar?

m2k_radar_2.trk

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Hi again,

 

I think I've experienced this weird behavior again; I mean...I think it has always been there, but I have a track file this time (or so I think).

 

It's a very simple one; just wait till the second minute (16:22 world mission time) and get to the cockpit view.

 

Radar on, HFR, 20nm range, azimut neutral (in the midle); there's a SU-27 coming hot on me, straight on, co-altiture. Close. Nothing shows up.

 

I can see it in front of me as a black dot; I can even start making its sillouette as it approaches, but the radar showed nothing for entire time until the SU27 just zoomed past me.

 

Maybe it's just me and I'm doing something wrong, or maybe I missed something somewhere...shouldn't that SU27 have showed up at some point on the radar?

 

Ok, I watched your track, took some data in the cockpit and F10 view.

 

At some point:

The Su-27 is 2.9Nm ahead at 6870ft.

You're flying at 4677ft.

On the VTB the radar cursor is:

- 12 Nm

- Max Alt = 12000ft

- Min Alt = 2000ft

 

Converting everything in metric system and doing some trigonometry (Arc Tan):

- The Su-27 is 7,09° above you => confirmed visually in the cockpit by the position in the HUD.

- Your radar scan zone is +5.9°/ -2.1° (actually it's a little bit less than that, but the radar cursor data being x1000ft it isn't accurate enough).

Scan zone centered roughly 1.9° above horizon (again coherent with - mark on radar vertical scale in head down)

 

So the Su-27 is just above you scan zone = NO BUG

 

If you can see it, stop messing with your radar head down, use close combat mode. It's designed to lock what you can see.:thumbup:


Edited by jojo

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What is the aspect of the target when you can't detect it at 30Nm ?

Hot or cold ?

 

I have tested that in DCS (M-2000C and F-15) we have poor radar range on cold target, especially in HPRF.

 

 

 

LOW PRF should be used when a target is cold in M2kC and F-15. This is my experience anyway.

 

I believe in mirage that is indicated as BVR in top right corner of radar screen when you are in low prf mode

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Mirage doesn't have MPRF just interleaved H/L. The labels are HFR BFR and ENT. H haute (high), B basse (low), and entrelace (interlace).

 

22,000' following 25,000', Mirage 2000C

Detection

1 Bar +-10 Az

Basse appear 13.2nm disappear 13.6nm

Entrelace appear 13.2nm 13.7nm

Haute appear 13.2nm disappear 13.6nm

Measured via F10 map and is therefore 2D range not slant

 

In this case PRF or filter mode made no significant difference to detection range. Remember this is 1-bar 10-az, the smallest possible scan volume and was trained exactly where target turns out to be.

 

Reverse the heights, 25kft following 20kft:

B a 8.9nm d 9.25nm

E a 8.85nm d 9.1nm

H a 8.9 d 9.10nm

 

Lookdown penalty is clearly demonstrated. Difference between mode is within measurement error. Mirage detecting Mirage in tail-chase is 13.2-13.7nm lookup and 8.9-9.1nm lookdown.

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Ok, I watched your track, took some data in the cockpit and F10 view.

 

At some point:

The Su-27 is 2.9Nm ahead at 6870ft.

You're flying at 4677ft.

On the VTB the radar cursor is:

- 12 Nm

- Max Alt = 12000ft

- Min Alt = 2000ft

 

Converting everything in metric system and doing some trigonometry (Arc Tan):

- The Su-27 is 7,09° above you => confirmed visually in the cockpit by the position in the HUD.

- Your radar scan zone is +5.9°/ -2.1° (actually it's a little bit less than that, but the radar cursor data being x1000ft it isn't accurate enough).

Scan zone centered roughly 1.9° above horizon (again coherent with - mark on radar vertical scale in head down)

 

So the Su-27 is just above you scan zone = NO BUG

 

If you can see it, stop messing with your radar head down, use close combat mode. It's designed to lock what you can see.

Nice JoJo, good stuff. At closer ranges it's more difficult to get the scan zone right. OP's workaround also resets the scan zone. Maybe a buttonpress on the resume search button would have been enough in these situations. OP, thanks for providing a track.
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