JSOW Differences between TOO and PP

[stenji]

I understand with PP mode I have to dial the target coordinates and altitude on UFC, in TOO I have to designate the waypoint as target. Is the only difference?

[Dagger71]

Pretty much. Think of PP as being done after/during mission briefing via data cartridge (maybe we will get it at one point???)

 

TOO would be done during the mission using the TGP

 

 

The way it's implemented in game is "kind of" backwards. Prior to getting the TGP, TOO used waypoint coordinates where as PP mode is added on the fly.

Edited August 25, 2019 by Dagger71

[Harker]

PP relies on coordinates that are known before the mission or are passed on to the pilot/aircraft from an outside source. They can also be fed into the aircraft via a data cartridge or a similar system.

TOO uses targets independently generated by the aircraft's own sensors or systems, be it stored waypoints, the targeting pod, the A/G radar or the JHMCS.

Nomenclature aside, the difference is that. PP uses outside coordinates info, TOO uses coordinates you generate yourself.

[Harlikwin]

So PP is using "absolute cords" mode while "TOO" is using the relative mode of the JDAM then?

[Santi871]

So PP is using "absolute cords" mode while "TOO" is using the relative mode of the JDAM then?

 

No, PP uses predefined coordinates and parameters that are (normally) created on a computer outside the aircraft, then loaded into the aircraft via data cartridge. The last part isn't in yet, so we have to enter them ourselves via the UFC.

 

TOO uses the current A/G designation's coordinates, which are produced by any onboard sensor (TPOD, HUD, JHMCS, A/G radar), or by designating a waypoint (WPDSG).

[Habu_69]

TOO should prove much more useful when the markpoint system is implemented, so that waypoints can be generated on the fly with onboard sensors,

[viper2097]

So PP is using "absolute cords" mode while "TOO" is using the relative mode of the JDAM then?

 

You may technicaly correct ;).

Needed to think about that a few seconds...

But I'd guess that the GPS from the Hornet would be as accurate as the JDAM GPS.

[Harlikwin]

No, PP uses predefined coordinates and parameters that are (normally) created on a computer outside the aircraft, then loaded into the aircraft via data cartridge. The last part isn't in yet, so we have to enter them ourselves via the UFC.

 

TOO uses the current A/G designation's coordinates, which are produced by any onboard sensor (TPOD, HUD, JHMCS, A/G radar), or by designating a waypoint (WPDSG).

 

Yes I think that is what I'm saying.

 

JDAM "absolute mode" uses actual real world coordinates. I.e. fly to point XYZ

JDAM "relative mode" uses the less accurate TPOD/sensor generated coordinates. i.e. plane thinks we are at XYZ, and relatively speaking the target is at range A, and bearings B/C, assume that XYZ are "correct" and fly to derived point XYZ'.

 

This is because the TPOD generated coordinates have to contend with the planes own spherical error position, which is a major contributor to inaccuracy, but by using relative mode you ignore that error (there are also pointing errors, pilot errors etc.)

[Santi871]

Yes I think that is what I'm saying.

 

JDAM "absolute mode" uses actual real world coordinates. I.e. fly to point XYZ

JDAM "relative mode" uses the less accurate TPOD/sensor generated coordinates. i.e. plane thinks we are at XYZ, and relatively speaking the target is at range A, and bearings B/C, assume that XYZ are "correct" and fly to derived point XYZ'.

 

This is because the TPOD generated coordinates have to contend with the planes own spherical error position, which is a major contributor to inaccuracy, but by using relative mode you ignore that error (there are also pointing errors, pilot errors etc.)

 

You're on the right track, what threw me off is semantics - there's no "absolute" and "relative" coordinates. All coordinates are "actual real world coordinates" that represent a place somewhere on Earth with varying accuracy.

 

I'm not sure what you mean by "ignoring that error by using relative coordinates". That error still exists in the real world and is a consideration - whether it's modeled in DCS is another story. There's many ways of calculating those coordinates, and they all have different amounts of error, which as you said depends on the aircraft position's/velocity's error as well as the method used.

Edited August 27, 2019 by Santi871

[Harlikwin]

You're on the right track, what threw me off is semantics - there's no "absolute" and "relative" coordinates. All coordinates are "actual real world coordinates" that represent a place somewhere on Earth with varying accuracy.

 

I'm not sure what you mean by "ignoring that error by using relative coordinates". That error still exists in the real world and is a consideration - whether it's modeled in DCS is another story. There's many ways of calculating those coordinates, and they all have different amounts of error, which as you said depends on the aircraft position's/velocity's error as well as the method used.

 

I may be wrong on the semantics :) , but as I understand it absolute mode vs relative mode are real things in JDAM speak. And one of the reasons you primarily use the JSOW in PP mode is that TPODs can't generate good coordinates for long range strike (I'm sure they are fine at shorter ranges). Also one of the other less realistic things I see are people sending each other TPOD generated coordinates and they are "accurate", which wouldn't really be the case kind of a better than nothing scenario, or use your TPOD to look over here... And using the "relative" mode of the JSOW/JDAM basically helps with the inaccuracy of the absolute coordinates generated. There is a good detailed paper on all this pertaining to use of the TPOD and the harrier, and the problems they had with "absolute" coordinates only, because of a bug where they couldn't use relative mode, which in a nutshell removes some of those inaccuracies. TPOD inaccuracy issues are also solved by second generation JDAMs with terminal seekers. If tpods were good enough, and JDAM's were actually accurate enough with just GPS you wouldn't need terminal seekers.

 

I doubt any of this modeled in DCS. Where all our munitions are magically accurate... Except guns ;)

Edited August 27, 2019 by Harlikwin

[=Mac=]

Please ignore this pertaining to DCS. This is simply a theoretical yammer:

 

There is no such thing as a physically accurate, perfect point anywhere in the universe. If you try to say something is EXACTLY here or there, you will always (theoretically) be off by some small amount... either a couple miles, a couple inches, a couple millimeters, a couple angstroms, a couple widths of a quark... etc. There is no such thing as exactly here. (I'm playing with Zeno's Paradox, by the way.)

 

Oddly enough, there is no such thing as NOW, either. It's always slightly (or a lot) in the future or always slightly (or a lot) in the past. Now cannot ever exist.

 

I'm sure you will have to think about it to actually get it. Nevertheless, theoretically speaking, it's all true. Practically, however, it's time for me to stop yammering.

[Harlikwin]

Please ignore this pertaining to DCS. This is simply a theoretical yammer:

 

There is no such thing as a physically accurate, perfect point anywhere in the universe. If you try to say something is EXACTLY here or there, you will always (theoretically) be off by some small amount... either a couple miles, a couple inches, a couple millimeters, a couple angstroms, a couple widths of a quark... etc. There is no such thing as exactly here. (I'm playing with Zeno's Paradox, by the way.)

 

Oddly enough, there is no such thing as NOW, either. It's always slightly (or a lot) in the future or always slightly (or a lot) in the past. Now cannot ever exist.

 

I'm sure you will have to think about it to actually get it. Nevertheless, theoretically speaking, it's all true. Practically, however, it's time for me to stop yammering.

 

LOL... You're right of course its all moving and relative to something. We just have a defined reference frame we are working in though so we can be "absolute" there.