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Target Point HUD symbology


Donglr

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Hi, I was giving the old F18 a spin and a question regarding the HUD symbology came up.

When I WPNDSG the current waypoint as the target point, I get a solid diamond without a dot in it on the HUD. At the same time my TGP slews to that point and is in "diamond moveable mode" (for lack of a better word). When I slew my TGP around the diamond in the HUD does not slew with it. I then press TDC depress and the HUD diamond jumps to the location my TGP is pointing at and the diamond is replaced by a smaller, dashed version with a dot in it. When I then slew the TGP the HUD diamond moves with it. I am now trying to make sense out of the F18 target point concept and how the target point is related to where the TGP is looking.

 

1. My assumption is than when I would drop a GBU right after I WPNDSG a waypoint and get the solid-no-dot-diamond on the HUD that GBU would hit the diamond, even I I slewed the TGP to another place WITHOUT pressing TDC depress afterwards. Is this correct? This would mean, that the target point is not necessarily associated with where the TGP is looking.

 

2. When I then TDC depress and I get the dashed-dot-diamond in the HUD the target point is moved to where the TGP is looking and if I were to drop a GBU it would impact where the TGP is looking. Correct? From that I take that the TDC depress "takes over" target point creation authority for the TGP. From that point where ever I point my TGP my target point is updated to the TGP and I do not have to TDC depress to update my target point location. So the concept behind all of this is that the target point and the TGP point are in principal two separate things (as proven by the WPNDSG diamond being somewhere else than the TGP), but once I press TDC depress the target point gets "slaved" to the TGP. Is that a correct way of describing how it works?

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Yup, you've mostly figured it out.

 

The HUD shows two types of TD diamonds. A solid diamond is a fixed designation point that cannot be moved or slewed. A broken diamond indicates a point that can be slewed.

 

When you designate a waypoint, it creates a fixed designation at that point, a solid diamond. At that moment other sensors and weapons are commanded to look at that point - the FLIR will slew there, uncaged Mavericks will slew to that point, and GPS weapons in TOO mode will write that point as their target for example. The FLIR can be slewed off the target point in this mode without disturbing the designated point. If you wish to make a new DT point with the FLIR, you depress the TDC. Doing that moves the DT point to the FLIR point, and the FLIR crosshair changes to a diamond. The diamond in the HUD now changes to indicate the TD point is in a slewable mode. If you change the FLIR into a tracking mode - either area or point - you will no longer be able to slew the FLIR and the diamond in the HUD will become solid again. To make things a bit more confusing: in point track the TD point will be placed at the point you acquired the point track; if you're point tracking a moving object you'll need to TDC Depress to update the DT location.

 

Bombs in AUTO delivery will always calculate release point based on the TD point. If you want to release on a waypoint, WPDSG is all that's needed. If you want to drop on what you're looking at in the FLIR, you'll need to TDC depress so that the FLIR takes over target designation.

 

A side note: the button on the HSI and SA Pages is "WPDSG" - Waypoint Designate. Not Weapon Designate. All it does it designate the currently selected waypoint (or Markpoint, or OAP) as the current designated point.

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Also in AA mode now there are "IN LAR" indication when we can fire the missile, instead of "SHOOT". What means that "IN LAR"???

 

Per Google: The acronym LAR is short for Launch Acceptability Region or Launch Acceptable Region. The term is applicable to bombs, rockets, and missiles whether the weapon is designed to engage a target on the ground or in the air. The LAR defines a region of conditions where a weapon can be successfully launched to reach a specified target.

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Per Google: The acronym LAR is short for Launch Acceptability Region or Launch Acceptable Region. The term is applicable to bombs, rockets, and missiles whether the weapon is designed to engage a target on the ground or in the air. The LAR defines a region of conditions where a weapon can be successfully launched to reach a specified target.

 

IN LAR shows shows instead of SHOOT, when locked on a friendly. It’s bad form for the avionics to tell you to shoot a friendly.

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IN LAR shows for friendly, ambiguous and unknown, as it should. Only targets confirmed hostile with the ROE matrix get the SHOOT cue.

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  • 2 months later...
On 11/1/2020 at 1:27 PM, Bunny Clark said:

The diamond in the HUD now changes to indicate the TD point is in a slewable mode. If you change the FLIR into a tracking mode - either area or point - you will no longer be able to slew the FLIR and the diamond in the HUD will become solid again. To make things a bit more confusing: in point track the TD point will be placed at the point you acquired the point track; if you're point tracking a moving object you'll need to TDC Depress to update the DT location.


After playing with the LITENING for a bit tonight, I found something that's confusing me.  Everything works as documented until you assign the TDC to the HUD/HMD and start moving the cursor.  Once you've done that, there is no way to get the TD diamond on the HUD to go solid again.  Switching to ATRK/PTRK doesn't have any effect on HUD TD symbology.

 

Once a ground target has been designated, I've also had trouble with losing ground stabilization with the target designated cursor the FLIR format (diamond reticle) after using the HUD to slew.  It's not a pure snowplow movement but there is more drift than a true stabilized position.  It can make refining target points more difficult.  It doesn't happen all the time so maybe there's something I'm missing.

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There are two things here:
Solid diamond after HUD designation.  If you initially use the TGP for designation then toggling between INS and ATRK/PTRK should  change the diamond from dashed to solid.  If you change to HUD designation and then move the dashed diamond then simply toggling the TGP wont change the diamond, since the HUD and INS are driving the TGT designation.  If you want a TGP designation then you should assign TDC back to the TGP (which you are doing) and then TDC depress.  After that you should see the solid/dashed behaviour  map back onto the TGP mode as before.  I have no idea if this is how the real jet works (clearly) but that seems to be how our DCS hornet works and it makes logical sense.

 

The drift - this is because HUD/HMD designations assume the designated point is at 0' MSL unless you are using AGR ranging when you designate.  The elevation error will cause the drift.  I have one (unconfirmed) verbal source that this is how the actual jet was in the early 2000's when our DCS Hornet was built.

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Regarding the drift and 0ft MSL, it shouldn't be an issue for a Hornet equipped with TAMMAC, because it has DTED elevation data available to it. And our jet should be equipped with TAMMAC (although the current HSI layout doesn't reflect that).

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6 hours ago, Scaley said:

If you want a TGP designation then you should assign TDC back to the TGP (which you are doing) and then TDC depress.  After that you should see the solid/dashed behaviour  map back onto the TGP mode as before.


Thanks for the additional info.  Everything made sense except this.  I still could not get this to work.  Oh well, it's not a big deal and more like a case of "My arm hurts when I do this, doctor."  Dr: "Well, don't do that then."

 

I'm simply at the stage where I'm trying to unravel the various systems in the Hornet so I can have a better understanding of all the fundamentals of systems/sensor/weapons management.  I enjoy understanding the results of all the button-mashing and knob-twiddling I'm doing in the cockpit.

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7 hours ago, Harker said:

Regarding the drift and 0ft MSL, it shouldn't be an issue for a Hornet equipped with TAMMAC, because it has DTED elevation data available to it. And our jet should be equipped with TAMMAC (although the current HSI layout doesn't reflect that).

 

Interesting info.  I definitely don't want to disagree with you since I have zero first hand knowledge, but someone else who worked on the real jet told me the era aircraft we have didn't have TAMMAC.  It's not in the NATOPS for 2000, but it is for 2008...  I guess we'll have to wait and see what ED decide to model to see if we get sea level designations or DTED elevations.  

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9 hours ago, Harker said:

Regarding the drift and 0ft MSL, it shouldn't be an issue for a Hornet equipped with TAMMAC, because it has DTED elevation data available to it. And our jet should be equipped with TAMMAC (although the current HSI layout doesn't reflect that).

There was a time shortly after they added JHMCS when they had TAMMAC and JHMCS, but couldn't use the DTED to drive the HAT. Before JHMCS AGR was used which was fine, but then JHMCS allowed designations beyond 60 degrees of azimuth and problems occurred. So no, just because we have DTED doesnt mean it should be able to resolve the HAT (also DTED is quite low resolution)

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4 hours ago, Scaley said:

 

Interesting info.  I definitely don't want to disagree with you since I have zero first hand knowledge, but someone else who worked on the real jet told me the era aircraft we have didn't have TAMMAC.  It's not in the NATOPS for 2000, but it is for 2008...  I guess we'll have to wait and see what ED decide to model to see if we get sea level designations or DTED elevations.  

I also don't claim to have first hand knowledge. I'm just taking my info from NATOPS and USN yearly reports. IIRC, TAMMAC should have been introduced into the fleet by mid-2000s. However, I don't know if our Lot 20 Hornet got it later. But if we didn't have TAMMAC (or at least DTED), we also wouldn't be able to do things we already do, in DCS. The FLIR, for example, wouldn't be able to generate elevation data, but it does. Also, we already have things that came after TAMMAC was introduced, if I'm interpreting docs correctly.

3 hours ago, Swiftwin9s said:

There was a time shortly after they added JHMCS when they had TAMMAC and JHMCS, but couldn't use the DTED to drive the HAT. Before JHMCS AGR was used which was fine, but then JHMCS allowed designations beyond 60 degrees of azimuth and problems occurred. So no, just because we have DTED doesnt mean it should be able to resolve the HAT (also DTED is quite low resolution)

Huh, I didn't know that. Interesting. I'm guessing the JHMCS wasn't integrated fully, yet. I always thought it was a 2-step process: JHMCS designates LatLong and then DTED gives elevation. From your description, it sounds like the JHMCS still waited for AGR elevation and when it couldn't get it, defaulted to a set value (0 MSL here).
And yeah, DTED, depending on the level, can be quite coarse, but it should still yield something close to 0 AGL, unless there's a very sudden elevation change.

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It can't be a separate 2-step process without bringing tons of errors in. The DTED has to be used to find the intersection between the LOS from the aircraft own position and the ground. This drives both the lat/long AND elevation values.

Otherwise you have to assume that everything is at a fixed altitude value (generally 0 MSL) and the intersection will give you lat/long and 0 elev. Then using the DTED at that specific position will lead to drastic errors whenever the terrain is not close to 0 MSL. For example, pointing a designation at flat ground but at 4000 ft in elev will make the designation appear much further behind the actual point you've designated.


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It can't be a separate 2-step process without bringing tons of errors in. The DTED has to be used to find the intersection between the LOS from the aircraft own position and the ground. This drives both the lat/long AND elevation values.

Otherwise you have to assume that everything is at a fixed altitude value (generally 0 MSL) and the intersection will give you lat/long and 0 elev. Then using the DTED at that specific position will lead to drastic errors whenever the terrain is not close to 0 MSL. For example, pointing a designation at flat ground but at 4000 ft in elev will make the designation appear much further behind the actual point you've designated.
True, true. Especially at higher elevations, the error would be too great. Which is what we probably see in DCS.

BTW, I tried yesterday with AGR enabled, within the radar FOV and it still showed 0-2 MSL, while the real one was more like 5000.

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