How does the Viper ground stabilize the TGP, calculate the CCIP pipper, etc.?

[Xavven]

I believe I read that the A-10C has a very detailed ground terrain altitude database, so combining that with aircraft position and attitude data, the TGP can ground stabilize and the aircraft can calculate impact points for munitions. Is that correct?

 

And does the Viper have the same database, or does it use ground radar to achieve this? Or something else?

[SpaceMonkey037]

So, the TGP can ground stabilize to a somewhat degree using only DTED (digital terrain elevation data, a database of terrain altitudes) , but this is a pretty rough system. In area track (what you would use to track the ground) it uses the IR camera to track IR signatures that have a contrast to the surroundings. It uses these IR signatures to track any area, not necessarily the ones that have an IR signature (don't confuse this with point track as that simply tracks a single IR signature) .It can therefor track in area track only by using the IR camera, although I think it also uses the terrain altitudes to give a better transition if it loses IR signatures. Once it's gotten a good track it can keep the track only by using the INS, however for slewing the TGP around you will require either the IR camera or DTED. For this reason if you've got a good track and mask the target you will be able to keep a close track on the target only with INS. In INR mode, the TGP uses DTED and INS and not the IR camera. Lasing is also a way to improve a ground track.
In short, it uses a combination of DTED, IR camera and the INS to keep the TGP ground stabilized.

 

As for CCIP and all the other A-G modes it primarily uses the radar. It can operate using DTED, but this will give you the worst possible results. It can also use the TGP laser. Hope that helps! Feel free to ask questions if anything was unclear!

Edited February 2, 2021 by SpaceMonkey037

[Xavven]

Thanks! That explains it perfectly

[Bunny Clark]

The TGP has three tracking modes:

 

INR is an inertial track. It uses aircraft movement combined with the DTED, as SpaceMonkey explained above, to keep the TGP pointed roughly in the same spot. An INR track can continue pointing in generally the same area even if the target location is masked by the aircraft or terrain. 

 

Area track uses image analysis of the entire scene to keep the pod pointing at the same spot. It looks at features visible in the pod, not just contrast, but any detectable patterns, and uses the motion of those patterns combined with the movement of the jet to stabilize the crosshairs as much as possible. Area track will revert to INR backup if the pod is masked by the aircraft, and if the target area is masked by terrain the tracked area will jump to the piece of terrain that got in the way. 

 

Point track looks for a area of high contrast in the center of the crosshairs and if it can isolate a clear shape it will track the center of that shape. This is most reliable in an IR camera mode, but will work in TV mode as well if you can get enough contrast with your target. Point track is the most precise tracking mode and will also allow you to track a moving object. A point track is lost if the TGP is masked by either the aircraft or terrain. 

 

Slant range to a target or CCIP piper can be determined by using the FCR, TGP laser ranging, or the radar or barometric altimeter in conjunction with the DTED by doing some trigonometry. Which method is currently being used is indicated by the letter in front of the current slant range in the HUD, i.e. if the HUD says "F027.5" your target is 27.5 miles away and that range is being provided by the radar (FCR).