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Helmet Qing takes ages in the Viper compaired to Hornet.


FuY
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There is only one mode possible with HMCS FCR cueing. I'm guessing this has nothing to do with HMCS and would have the same performance with ACM BORE straight ahead on the HUD. I would compare radar performance between HMCS and BORE before I concluded there is anything special about HMCS.

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Tested with just plain ACE BORE. The radar just is bad in certain geometries. Steep downlook at even a few miles and it will take a while to lock if at all. I wasn't able to get lock in in some situations until 0.7nm slant. Make sure you're not holding TMS forward with ACM BORE or HMCS as the radar won't radiate until TMS forward is released.

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12 hours ago, Frederf said:

Tested with just plain ACE BORE. The radar just is bad in certain geometries. Steep downlook at even a few miles and it will take a while to lock if at all. I wasn't able to get lock in in some situations until 0.7nm slant. Make sure you're not holding TMS forward with ACM BORE or HMCS as the radar won't radiate until TMS forward is released.

It's not just look down. The radar is sometimes just completely borked in ACM.

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I think the tag "correct as is" is absolutely misleading.

You encounter a combination of issues ED is aware of for a long time, but did not fix them (yet). They only seem to adress only the most pressing issues, while developing the rest of F16  module further. Maybe adressing these issues will happen in a second development pass. I dont know...

 

Its not a JHCMS issue, its more of a radar issue. The combination of the issues you are running into (that are announced to be fixed) are:

-Radar look down ( will be tweaked)

-Radar locking the wrong target, if mutiple are close together (Investigating)

Get ready for that this thread also being merged with one of those 🥳

The corresponding threads are:

 


Edited by darkman222
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Since it is now taged as "correct as is" 
can we get an explaination why it is so ?!

Given the troubled history of the viper i still tent to think this is a bug. 
but ofc if SME´s have, for example confirmed this behavior it would be nice to know. 


Edited by FuY
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Like I said, it does not make sense being labelled "correct as is" because JHCMS might be correct as is, but its a radar issue. You can try the same without JHCMS with the HUD radar boresight cross with the same results. Both radar issues have status: "investigating" or "will be tweaked". Just wait until the mods come online to clarify.

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@FuY Isn't that all about radar filtering slow objects approx. <20knts speed difference (closure rate, Zero Doppler Filter)?

Notice that in F16 video You're attacking target that flying in same direction as You (so Zero Filter cutting it at the beginning, later You develop speed and we can see 60~70knts speed diff when You can lock it).

In F18 vid You're attacking TRGT that flying opposite direction (we can see closure rate of 270~300knts) so You can lock it w/o any problem.

Remember that, if You chasing another plane with minimum closure rate (speed difference below ~20 knots) You won't see it in any radar because of Zero Doppler Filter.

That's why we're using also FOX-3s 😉 You can not always rely on radar.

https://www.youtube.com/watch?v=N8Z3ta1v1po


Edited by Bricux
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vor 5 Stunden schrieb Bricux:

@FuY Isn't that all about radar filtering slow objects approx. <20knts speed difference (closure rate, Zero Doppler Filter)?

 

that´s not it. 
you can look on targets below you (cluttered by ground returns) 
and @ 0 relative velocity. 



80% of the time the radar works as expected and simular to the hornet. 
the other 20% it takes up to 20 sec for a look independent of relative velocity and other variables. 

I fly a lot of Hornet and Viper. 
The hornet does not have this issue. 
From my understanding its a bug within DCS that has been reported multible times 
and always been flaged as "correct as is" 
yet no explaination has been given why this is not "just" a bug.

 


Edited by FuY
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6 hours ago, Bricux said:

Remember that, if You chasing another plane with minimum closure rate (speed difference below ~20 knots) You won't see it in any radar because of Zero Doppler Filter.

That's why we're using also FOX-3s 😉 You can not always rely on radar.

https://www.youtube.com/watch?v=N8Z3ta1v1po

 

Unfortunately you’re interpreting Doppler filter incorrectly. Right idea, slightly off on the application.

The Doppler filter exists to prevent ground clutter from showing on the radar. Therefore, it filters out anything with 0 relative speed to the ground, not to the aircraft.

For example, if I’m travelling 300kts ground speed, anything with 300kts closure to me will be filtered out, not something with 0 relative closure to me. The big mountain in front of me will be coming towards me at 300kts, that’s what gets filtered out. The aircraft in front going the same speed as me will have a different Doppler shift from that mountain, and will be seen.

If I want to hide in the Doppler filter, I “notch” the other guy’s radar by putting him at 90 degrees, not flying towards or away from him, creating 0 relative speed in reference to the ground. It’s as if he’s approaching a large ridge line perpendicular to his path. That ridge line is filtered out by the Doppler filter. If I fly along the length of that ridgeline, I’m creating the same Doppler shift as that ridgeline and I’ll be filtered out.

It is a bit more complex then that when you start talking about look up vs look down, etc - but that’s the gist.

 

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9 minutes ago, Sandman1330 said:

Unfortunately you’re interpreting Doppler filter incorrectly. Right idea, slightly off on the application.

The Doppler filter exists to prevent ground clutter from showing on the radar. Therefore, it filters out anything with 0 relative speed to the ground, not to the aircraft.

For example, if I’m travelling 300kts ground speed, anything with 300kts closure to me will be filtered out, not something with 0 relative closure to me. The big mountain in front of me will be coming towards me at 300kts, that’s what gets filtered out. The aircraft in front going the same speed as me will have a different Doppler shift from that mountain, and will be seen.

If I want to hide in the Doppler filter, I “notch” the other guy’s radar by putting him at 90 degrees, not flying towards or away from him, creating 0 relative speed in reference to the ground. It’s as if he’s approaching a large ridge line perpendicular to his path. That ridge line is filtered out by the Doppler filter. If I fly along the length of that ridgeline, I’m creating the same Doppler shift as that ridgeline and I’ll be filtered out.

It is a bit more complex then that when you start talking about look up vs look down, etc - but that’s the gist.

 

So it's about way of doppler radar works? If tracked object travels at same speed as emitter there is no doppler effect.


Edited by Bricux
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Doppler is used, sometimes, as a filter with Doppler radars to reject certain radial velocities. The primary filter is to remove ground returns which are at a certain frequency shift from the emitted. For the ground this is the speed of the ground coming at the "stationary" airplane (motion being relative). For this filter following a target at 300 knots at 300 knots is fine because it wouldn't be filtering out returns at zero relative. The filter would be removing 300 knot closure frequencies, aka the ground, not 0 knot relative.

It's not like a PD radar needs the Doppler effect to see returns. A return of no Doppler effect is just as visible as any other. It's simply extra information to which it can apply a filter. The choice of if and where to place any filters is arbitrary.

But there are other filters, side lobes, maybe some zero relative factors. A lot of filters aren't binary yes/no but are extra thresholds which can have sufficient SNR to work through. Some radar modes (uplook) skip certain filters as not needed. I think ACM BORE tests various range gates in a rolling "inside out" pattern to look through particular chunks of range. E.g. a target 1000' away even if lookdown can safely ignore all ground returns by simple time domain.

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On 12/22/2021 at 11:44 PM, Sandman1330 said:

Unfortunately you’re interpreting Doppler filter incorrectly. Right idea, slightly off on the application.

The Doppler filter exists to prevent ground clutter from showing on the radar. Therefore, it filters out anything with 0 relative speed to the ground, not to the aircraft.

There isn't just a single filter, and yes there will usually be one that filters relative 0 to the aircraft as well as the one you mentioned.

All leakage from TX to RX, scattering from within the aircraft eg the radome, and reflections from the ground perpendicular to the aircraft (eg from sidelobes) will have no doppler shift.

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  • 3 weeks later...
32 minutes ago, Csgo GE oh yeah said:

This is not a helmet thing i believe. 
The same thing happens in vertical scan, or hudscan, or any other ACM mode. 

ACM in F16 seems extremely unreliable 

Yup, even in 0 clutter lookup enviroments

 

See this thread 

 

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