AGR Track

Did some researching and discovered a few things about AGR:

 

1. It definitely does SOMETHING. Take your hornet for a spin in the mountains (Cacuses). Point ccip cross on mountain, THEN SCS up. The reticle will shift.

 

2. The velocity delta in the format is the difference in the radar calculated aircraft velocity and the INS. If you have velocity errors in the INS, this is one method you could find them. I don't know if you can 'force' velocity errors in the INS, but if you could, this would show some non-zero value. PVU's I know are generally less accurate than the general accuracy of a coupled INS, so it makes sense for all of us so far, this number is 0.

Very nice findings! I will try them out today.

Did some researching and discovered a few things about AGR:

 

1. It definitely does SOMETHING. Take your hornet for a spin in the mountains (Cacuses). Point ccip cross on mountain, THEN SCS up. The reticle will shift.

 

2. The velocity delta in the format is the difference in the radar calculated aircraft velocity and the INS. If you have velocity errors in the INS, this is one method you could find them. I don't know if you can 'force' velocity errors in the INS, but if you could, this would show some non-zero value. PVU's I know are generally less accurate than the general accuracy of a coupled INS, so it makes sense for all of us so far, this number is 0.

Thanks for the heads up. I'll mess around with it and comment here if I find anything worth mentioning.

I don't seem to be able to make it work like Rifle described. Not only my ccip cross won't change but the delta values also stays in 0. I did quite a few runs in the mountains.

It has to to with at what angle you're diving. Let me see if I can find that video again...

EDIT:

It has to to with at what angle you're diving. Let me see if I can find that video again...

 

EDIT:

Nice. So it is definitely "correcting" any erros in the DTED database, assuming there's one simulated already. Funny thing is, the radar wave should be absorbed by the water and the ccip cross should not be accurate.

I don't seem to be able to make it work like Rifle described. Not only my ccip cross won't change but the delta values also stays in 0. I did quite a few runs in the mountains.

You should only see 0 unless a speed error accumulated in your INS. In reality it would fluctuate a few knots because that's the margin of error for radar speed measurement. Speed errors in the INS likely are not modeled, so this value will always be 0.

Still can't find any info on AGR track for the Lot 20.

It has to to with at what angle you're diving. Let me see if I can find that video again...

 

EDIT:

It would be nice if you try that exact situation with the a10c, so we can determine if the DTSAS or DTED is simulated independently of the airframe and how it is actually simulated.

Thank you for this thread guys. I didn't know how to use FTT or AGR... in fact didn't really even know what they were or how to use them in the Hornet.

After 4 pages and some practice on the Test Range I'm pretty impressed by these new developments and now have a basic understanding!

Thanks!

You can also see the CCIP behavior change at low level over a city where the radar altimeter reading is constantly changing because of the buildings. With AGR on, the piper becomes more stable and does not bounce around seemingly because radar alt is not the method for impact point prediction.

However while the radar altimeter can see and detect buildings, the AGR seems it cannot. Selecting the gun with AGR on and pointing it at that really tall building on PG gives no range readings.

You can also see the CCIP behavior change at low level over a city where the radar altimeter reading is constantly changing because of the buildings. With AGR on, the piper becomes more stable and does not bounce around seemingly because radar alt is not the method for impact point prediction.

 

However while the radar altimeter can see and detect buildings, the AGR seems it cannot. Selecting the gun with AGR on and pointing it at that really tall building on PG gives no range readings.

What? Radar alt is never the mode so that doesn't make any sense. You are confusing DTED with radalt.

What? Radar alt is never the mode so that doesn't make any sense. You are confusing DTED with radalt.

It should be used, if radar ranging and DTED are not available, I think.

As for my findings, they are the same as the posters above. AGR works really nicely for uneven terrain. I tried with CCIP bombs, rockets and gun. As for the delta V, I never saw it being anything else than 0, even when I completely messed up my INS on purpose.

It should be used, if radar ranging and DTED are not available, I think.

 

As for my findings, they are the same as the posters above. AGR works really nicely for uneven terrain. I tried with CCIP bombs, rockets and gun. As for the delta V, I never saw it being anything else than 0, even when I completely messed up my INS on purpose.

Yes, but it is not the case he was reporting, he just mixed them up. What he sees in the piper is the DTED in action. The AGR is just faster and has real resolution.

Yes, but it is not the case he was reporting, he just mixed them up. What he sees in the piper is the DTED in action. The AGR is just faster and has real resolution.

I agree with you, yeah. We get a valid solution with both the radar and the radalt off, after all.

Oh, you meant radalt is never the mode currently, since we probably have magic DTED available all the time (since our HSI doesn't support TAMMAC yet).

 

I agree with you, yeah. We get a valid solution with both the radar and the radalt off, after all.

Yeapers! That's what I meant. And also yes, we have magic DTED and pretty much 70% of the aircraft's systems in the same state.

I'm not sure what is actually used to calculate the CCIP reticle but at low level when over a city you can watch your radar alt blip up and down as you fly over houses and such. Conversely you will see the CCIP reticle bouncing up and down as if the calculations are being made using rad alt. When you turn on AGR the reticle no longer bounces up and down and becomes more or less stable unless the terrain underneath the reticle itself changes.

It seems from what I have tested that AGR does not see buildings in DCS, but the radar altimeter sure does.

Here is a short video to visualize what I'm talking about.

Would DTED have the elevation data of not only terrain but every building large or small?

I'm not sure what is actually used to calculate the CCIP reticle but at low level when over a city you can watch your radar alt blip up and down as you fly over houses and such. Conversely you will see the CCIP reticle bouncing up and down as if the calculations are being made using rad alt. When you turn on AGR the reticle no longer bounces up and down and becomes more or less stable unless the terrain underneath the reticle itself changes.

It seems from what I have tested that AGR does not see buildings in DCS, but the radar altimeter sure does.

 

 

Here is a short video to visualize what I'm talking about.

 

 

Would DTED have the elevation data of not only terrain but every building large or small?

But your radalt isn't moving at all. The effect you are talking about does exist, but only ED knows what is causing it. Probably a couple of bugs.

It is moving which is why I looked at the rad alt dial. It does not update on the HUD indication however.

Also that was from a hot air start in the ME so I might have forgot to turn the HUD source to radar from baro, my bad. However the rad alt is moving on the dial.

Well, it seems we have a bigger issue in our hands cause that should not happen at all. Radalt is not the source of calculation unless commanded which isn't possible in the hornet right now.

I tried the same setup as @NeMoGas in Caucasus and saw the same thing. (Note: The RadAlt does move when you pass over a building, you just forgot to switch to RDR Alt on the HUD, your alt box would show R to the right).

I also performed a few tests to check the DTED accuracy and determine what elevation sources the Hornet uses.

I compared the behavior with the A-10C, using the embedded Digital Terrain System (DTS), which likely uses DTED Level 2 (30m spacing between points), it's not specified in the manual. The Hornet's TAMMAC should also use DTED Level 2.

Unlike a Digital Surface Model (DSM), DTED Level 2 does not contain building or vegetation information and represents the terrain only (might include very large man-made structures).

A-10C Tests:

Test 1: In the A-10C, flying over the city, the CCIP reticle did not account for buildings. This is correct, based on DTED data. It did not jump when I flew over buildings.

Test 2: I tried the Mk-82 and the gun in CCIP, on mountains slopes and peaks, approaching the target almost level. The CCIP solution caused me to several times miss my exact target on the slope or miss a mountain peak (the very top) with a Mk-82. This is normal and representative of the DTED's limited accuracy.

Conclusion: The A-10C works as it should.

F/A-18C Tests:

Test 1 (AGR On/RAlt On): In the Hornet, flying over the city with AGR On, the CCIP reticle did not account for buildings. It behaved the same way the A-10C did. This is incorrect, since the radar should be able to tell there is an obstacle.

Test 2 (AGR Off/RAlt On): Flying over the city with AGR Off, the CCIP reticle jumped when I was flying over a building, like it was using the RadAlt as the elevation source.

Test 3 (AGR Off/RAlt Off): Flying over the city with AGR Off, and RadAlt Off the CCIP reticle did not jump when I was flying over a building, behaving the same as in the A-10C. This is correct, assuming the Hornet uses DTED.

Test 4 (AGR On & Off/RAlt On): I tried the Mk-82 and the gun in CCIP, on mountain slopes and peaks, approaching the target almost level. While with AGR Off, my results were not great (normal), with AGR On, I got extremely accurate targeting data. much better than DTED Level 2 should be able to produce. This is also normal.

Conclusion 1: Based on Tests 1 and 4, the AGR does matter, but appears to not account for structures and trees yet, generating very good targeting data for terrain only. The terrain part works correctly, but AGR should be able to account for buildings, trees and whatever else might be there, since it's a radar return.

Conclusion 2: Based on Tests 2 and 3, it seems that in the absence of AGR, the Hornet will use a combination of Radar Altimeter data (if available) and DTED as the elevation source.

Bonus test - Mirage 2000C: I also run tests 1-4 with the Mirage, since it can use both AGR (TAS) and RadAlt data for targeting, but does not have DTED. Similarly to the Hornet, TAS does not account for structures and works well on steep terrain. With TAS Off, the behavior was the same over the city (wrong, since RadAlt is the only source), but correct in the mountains, where you can have a steep slope 1000 ft in front if you, but you won't get a correct firing solution without TAS, since the RadAlt reads a much lower elevation.

Bonus conclusion: The M-2000C AGR and RadAlt targeting does not account for structures.

Hot starts always throw me off and I forget to turn things on I would normally do during a manual start up.

Thanks for the testing info, hopefully this is just WIP stuff and will get fleshed out later in EA.

Harker, that's a great write-up.

It doesn't surprise me that AGR can't 'see' structures. Most sensors in DCS ignore the presence of structures (laser rangefinders, FTT doesn't recognize them, etc). I assume when these other sensors can recognize them, so will AGR.

The laser rangefinder on the A10C does see structures, but it is limited to the same range as the laser designator which is about 8-8.5nm. I tested this about a week ago. The F18 and F16 laser however does not unfortunately.

It doesn't surprise me either that the radar won't see structures and trees, it's normal in DCS and not critic IMHO. What it does feel bad is that the Hornet uses Radalt as a source without commanding it manually (turning radalt on does not involve turning it on for weapon delivery, two different things) or having DTED unavailable.