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Ground mapping radar (SAR)


TedStriker

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I was just wondering how well the synthetic appature radar will be modeled in the F15E. From what I recall, the targeting system for the F15E is very dependent on it and it would be disappointing to see it implimented the same way that the FLIR is in A10C (where somehow a tree puts out as much heat as a running tank).

 

Do DCS World objects have a "radar reflectivity" property assigned to them (as they should have for IR)? To really do it right, this value should change with the angle the radar hits it, but you can't have everything.

 

TedStriker

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1m resolution.

pentagn1.jpg

 

Radar modelation as a dynamic process will be a heavy process to atach to a CPU or GPU.

http://techdigest.jhuapl.edu/TD/td2502/Awadallah.pdf

 

The alternative will be the method used in Falcon 4 or Jane's F-15/FA-18, differentiating ground mapping and mobile objects maping given each method a precalculated image.

 

For sure Eagle Dynamics, in the DCS Fighter works, have already one method or more to solve this problem.


Edited by Xpto

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Radar modelation as a dynamic process will be a heavy process to atach to a CPU or GPU.

 

Not necessarily extensive to determine, do a top down render of that area and apply some image processing. Would still be better than a pre-baked image.


Edited by sobek

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  • 2 weeks later...
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I would be fine with the following implementation of non-SAR mode ground radar when dealing with the environment (this does not apply to vehicles):

 

  • Use the F10 map as a basis for the image (keep it simple). Pre-render the image to minimize real time processing.
  • Each type of terrain (or 3D object as required) has a reflectivity coefficient. For example, concrete reflects radar energy much better than soft dirt, so cities and some roads show up well on ground radar. Calm water usually shows up as a black hole. These coefficients would be applied during the pre-render.

 

This leaves elevation as the last variable (since the radar can't see through a mountain, and "mountain shadow" is also an indicator of when you must change course to avoid CFIT). For this, we go back to a simple method for determining radar detection envelopes when strike planning on older computer systems. Quite simply, the radar detection envelope for known SAM sites vs. your platform is precalculated based on incremental altitudes every 250 feet and stored in tables, so when you go into another altitude bracket you know where you stand in relation to the detection ability of other sites.

 

What I propose is similar, but reversed. Rather than using own altitude to determine likelihood of detection, use own altitude to determine ground radar envelope given surrounding terrain in small (e.g. 100-200 foot) increments. This way the PC would not need to do any real-time calculation, but rather could take a table-based approach to how much of a pre-rendered image could be displayed.

 

Vehicles would still need to be rendered in real-time, but at least this solution would give back some processing cycles.


Edited by Home Fries
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  • 8 years later...

 

 

Yea time to revive this thread given A/G radar is now a thing in DCS.

 

 

Strike Eagle's has a good Surface Radar for its generation of Radars.

 

Should have more advanced Air to surface mapping modes, and higher resolution sar compared to a USN F/A18 Hornet ( because USMC F/A18D's use a more sophiscated software, for the  recon role) 

 

 

jelCkVe.gif

 

 

 

 

From another thread regarding Strike Eagles Surface Radar

 

 

 

 

 

 


Edited by Kev2go
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An interesting white paper regarding APG70 that gives us some insight of capabilities. published in 1997.

 

 

https://www.researchgate.net/publication/235082355_Automatic_Target_Cueing_and_Operator_Performance_with_Enhanced_APG-70_Synthetic_Aperture_Radar_Imagery

 

 

"The F-15E Synthetic Aperture Radar (SAR) in High Resolution Map (HRM) mode has the capability to produce patch maps at eight different coverage sizes, ranging from 80 nautical miles (nmi) to 0.67 nmi. The 0.67 nmi map corresponds to an image resolution of 8.5 ft/pixel, which is currently the highest level attainable on the F-15E (Nonnuclear Weapon Delivery Manual). In order to provide the type of higher resolution imagery needed to support the application of ATC/ATR technologies, the Theater Missile Defense (TMD) office (ASC/FBXT) sponsored the development and testing of a new high resolution capability with a "smart" sensor management system for use with the APG-70 radar. The APG-70 was modified to include a New High Resolution Mode (NHRM ) with a patch size of 0.33 nmi, which corresponds to an image resolution of 4 ft x 6 ft (hereafter referred to simply as 4 ft). The smart sensor system will use the APG-70's SAR mode to search cued locations and locate likely targets using consecutive SAR patch maps of increasing resolution."

 


Edited by Kev2go
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After what we have in Hornet and Jeff AG radar (map mode) I'm not that enthusiastic about this function. In hornet its almost useless, its only good for ship and moving ground target track.
I cant believe we're waiting so long for this to be implemented only to find how useless this is.

Well I hope you're right Kev for the F-15E, at least as good as your gif pict.

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36 minutes ago, Oceandar said:

After what we have in Hornet and Jeff AG radar (map mode) I'm not that enthusiastic about this function. In hornet its almost useless, its only good for ship and moving ground target track.
I cant believe we're waiting so long for this to be implemented only to find how useless this is.

Well I hope you're right Kev for the F-15E, at least as good as your gif pict.

 

it should be. that Gif footage is in fact a Strike Eagle radar. From the documentary Desert Storm; the Air assault.  And as from that white paper which cited that information from the the Dash 34 weapons delivery manual unlike the Hornet the Strike Eagle has at least 8 mapping sizes not 3.

 

 

 

 


Edited by Kev2go
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On 6/6/2021 at 1:45 AM, Oceandar said:

After what we have in Hornet and Jeff AG radar (map mode) I'm not that enthusiastic about this function. In hornet its almost useless, its only good for ship and moving ground target track.
I cant believe we're waiting so long for this to be implemented only to find how useless this is.

Well I hope you're right Kev for the F-15E, at least as good as your gif pict.

 

I think you are missing how old this tech is and for what it was made.

I showed the Hornets A-G radar picture to my dad and he was able to make out a good amount of things, because he was trained to.

 

Just because it's not giving you a cristal clear picture like a 21 century targeting pod doesnt mean it is useless.

Fly the Viggen, learn how to use it.


Edited by Bananabrai

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I think you are missing how old this tech is and for what it was made.
I showed the Hornets A-G radar picture to my dad and he was able to make out a good amount of things, because he was trained to.
 
Just because it's not giving you a cristal clear picture like a 21 century targeting pod doesnt mean it is useless.
Fly the Viggen, learn how to use it.
I just based my oppinion on what I've seen and experience and I've asked many players online about this and they also agree with me. If it works for you then good for you. I also read on this forum that real life F-18 pilots dont use it that much because ofc they need to VID the target based on ROE something AG radar can not provide.

If you think you can provide a tutorial (I prefer a video) about how to use hornet AG (map mode) properly to find a tank in the ouskirt of a town for example, please do so. Thanks in advance.
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6 hours ago, Oceandar said:

to find a tank in the ouskirt of a town for example, please do so

And there is your problem. You are trying to get the radar to do something it's not designed to do (although on occasion it's possible - at short ranges the Viggen's radar is semi-decent for it but you need to really tweak the gain control for it to work well, and that's less annoying to do than in the Hornet). A2G modes are not for finding individual vehicles, especially if they are not moving. Any sort of TV or IR sensor will always be better for that because that's just how the laws of physics work.

 

Requiring VID is not the issue - it's not like it wasn't a problem during Desert Storm for instance. The A2G radar is there (mostly) as an aid to navigation if you need to hit a larger strategic object like a bunker, runway, shipyard, etc, especially in bad weather. For obvious reasons, that is not something that has been relevant in the last 20 years of COIN operations. What it's not there for, is plinking individual vehicles with LGBs and Mavericks, that's just a weird misconception that the DCS community has about how air to ground missions actually work.

 

edit: to further clarify, kev2go's post reports the imaging resolution of highest resolution mode in the Strike Eagle, arguably one of the better non-AESA a2g radars in the world, as ~5ft. That means that a BTR, which has a size of 10x25x8ft, would be ~10-15 pixels in size total - say, 3x5. Looking at Tomcat footage on YT, I would estimate that imaging resolution to be roughly ~10 times worse than even a LANTIRN pod, nevermind comparing the much better Litening or ATFLIR with the much worse APG 73.


Edited by TLTeo
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A-G radar is there to help you narrow down the area you would search with your pod, not to pin point the target. Unless you are going for a convoy, in which case being able to detect moving ground targets is very useful.


Edited by JB3DG
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As I understood, ground radars are used during bad weather mostly to look for buildings and things that highlight on the radar, not for finding vehicles.

 

Also, in DCS GMT is broken since the only vehicles you see are the ones made by the mision designer, it will not have any impact on civilian vehicles.

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On 6/7/2021 at 3:01 PM, Oceandar said:

I just based my oppinion on what I've seen and experience and I've asked many players online about this and they also agree with me. If it works for you then good for you. I also read on this forum that real life F-18 pilots dont use it that much because ofc they need to VID the target based on ROE something AG radar can not provide.

If you think you can provide a tutorial (I prefer a video) about how to use hornet AG (map mode) properly to find a tank in the ouskirt of a town for example, please do so. Thanks in advance.

 

Interesting. A story comes to my mind.

My dad once had a meeting where a bunch of engineers evaluated the uselessness of an AG radar of an unmentioned type of aircraft.

They were looking at a picture of a point of interest saying that it's completley useless. Then he stood up and explained what he could see on the debated picture.

They were pretty astonished.

 

I completely understand your point. I also think that it is a true statement that Hornet drivers didn't use it that much in RL.

You also mentioned the problem itself, VID and ROE. Different countries have different ROE and VID rules. 

 

So to meet on a neutral point here, it's true that in comparision even to 1990 TGPs the A-G radar is useless for your above mentioned example.

But that example is a pretty extreme one, because it is even hard with a TGP or with your eyes to find that tank in a town.

In crontrast to that, a tank in a town is a tank that can not adavance to fast towards your troops, so it also has a lower priority than one that is moving on open ground.

 

An A-G radar is always best on an aircraft that you use for the strike role. I think the Hornet was rarely used for that task.

Idealy you use the A-G radar to confirm a location of a FARP, or ships in a port, or aircraft on the apron of an airfield, when you either can not use a TGP due to weather or you do not have one available (say 1980s scenario for example)

It is crucial that you use gain an contrast, I think that is not something to explain easily and I don't know a video for that.

I learned it by playing around, that's all I can say, sorry. Small changes in these controls can have great effect.

 

Try it out, maybe you eventually will like it. And if not, I don't judge you.

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  • 3 months later...
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My understanding about AG radar usage in Gen 4 aircraft was its primary task was to remove INS drift in the pre GPS era (or due GPS jamming). The radar is used to identify a large object with a known location, such as a bridge, warehouse, runway threshold etc, whilst on the run in to the target. Then, using a known offset (bearing and distance) from this radar fix, the target position can be updated and displayed more accurately.

Whether you simply drop bombs on the updated designation in auto/CCRP, or use it to help visually acquire the target would be mission/weather/weapon dependent I guess.


Edited by norman99
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My understanding about AG radar usage in Gen 4 aircraft was its primary task was to remove INS drift in the pre GPS era (or due GPS jamming). The radar is used to identify a large object with a known location, such as a bridge, warehouse, runway threshold etc, whilst on the run to the target. Then, using a known offset (bearing and distance) from this radar fix, the target position can be updated and displayed more accurately.
This is true, however the F-15Es in desert storm claimed that they could identify an any aircraft on the ground and determine if it had fuel tanks... at a range of 30 nm.

It was a very powerful tool in the desert supposedly.
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