Wrong target coordinates

[tflash]

Is this a known bug? In the region of Achigvara near Gali I always get wrong coordinates from the JTAC: it should be in the GH12-GH13 grid, and I always get GH16 - GH17 coordinates, completely off the mark.

 

I thought I had the same problem near Kobuleti.

 

In attach a mission with only the necessary things in it to show what I mean. Contact the JTAC on FM 30 MHz, and you will get the wrong coordinates

FT new roadblock mission.miz

[tflash]

Hello Nate, could you look into this?

[Speed]

There is no problem that I can find here other than MGRS just being confusing sometimes. The coordinates given are GH12 coordinates, and in the 37T UTM grid (make sure you take note).

 

For example,

37T GH170284, where your APCs are, is within the 37T GH12 grid square

37T GH 170 284

 

I highlighted the relavent digits, and added a space between the MGRS digraph, and the easting and northing coordinates (that space is often omitted, but it is important to remember that the numbers in a MGRS grid represent both an x AND y coordinate!). Remember that 37T GH12 is a two digit grid, meaning that the six digit grid representation is this:

 

37T GH100200

 

(spaces removed)

 

Do take note that if you were to give these coordinates to someone else as say, a target, you wouldn't want to specify the grid square you were in before you first rounded to the nearest least significant digit (in this case, a two digit grid, that digit is in the tens of kilometers place). To properly give the coordinates of these targets to someone else, you would need to say that they are at 37T GH23, as 170 rounds to 200, and 284 rounds to 300. But these coordinates are within the grid square defined by the limits of 37T GH(1 to 2)(2 to 3), so the first digit of the easting will be 1, and the first digit of the northing will be 2. There's nothing wrong with the in game coordinates or with the mission editor map, it's just that MGRS coordinates can be confusing.

Edited January 18, 2012 by Speed

[tflash]

Hello Speed,

 

 

Thanks for your answer. My problem was that my CDU was set to 38T. Once I changed it to 37T, it all works fine (and indeed I was mistaken about GH170284 not being in GH12).

 

My question is now (can be a dumb one): how do I know it is 37T, since the JTAC omits the grid zone in his 9-line brief?

[effte]

You have to make a sanity check on the coords given. If they are too far off, suspect they're the wrong grid zone.

 

Our virtual JTAC is making a gross error, as the grid zone should always be given if there's any chance of ambiguity when omitting it.

 

I think plugging my UTM/MGRS introduction is in order.

 

Speed,

you never round when giving a lower-precision MGRS, you always truncate. I e, if you know the easting is somewhere between 16 and 18 and the northing is somewhere between 28 and 29, you give the coordinate as GH12 and not GH23. This of course means that if you are given GH12 for a coordinate, you start looking in the middle of the square GH12, i e around GH1525, and not in the SW corner of the square (GH1020). In your example, 170 becomes 1(00) and 284 becomes 2(00).

 

It used to be the other way around, but it was changed quite some time ago.

 

I suspect, but have not yet checked, that the systems in the simulated A-10 go about it the wrong way, ie focus on GH1020 rather than GH1525 when given GH12.

 

Cheers,

Fred

Edited January 18, 2012 by effte
Added bit about truncating and plug for introduction.

[Speed]

 

Speed,

you never round when giving a lower-precision MGRS, you always truncate. I e, if you know the easting is somewhere between 16 and 18 and the northing is somewhere between 28 and 29, you give the coordinate as GH12 and not GH23. This of course means that if you are given GH12 for a coordinate, you start looking in the middle of the square GH12, i e around GH1525, and not in the SW corner of the square (GH1020). In your example, 170 becomes 1(00) and 284 becomes 2(00).

 

It used to be the other way around, but it was changed quite some time ago.

 

I suspect, but have not yet checked, that the systems in the simulated A-10 go about it the wrong way, ie focus on GH1020 rather than GH1525 when given GH12.

 

Cheers,

Fred

 

Whoa, very interesting. Thanks! That goes against common math sense, but is that becuase... ahem.. the most common users of MGRS not have any common math sense? :P

 

And yes, MGRS is rounded in DCS from what I have seen. Go look at NATO.lua and see for yourself. They round.

[effte]

Aha, there we have it... nice, thanks for pointing the file out!

 

(Sound of furious LUA editing here)

 

I think my version of DCS:A-10 now truncates rather than rounds. It should also give me the GZD every time. With luck, I'll test it this weekend.

 

Hmmm... is the MGRS to TGP target conversion in a LUA somewhere as well?

 

Cheers!

/Fred

 

P.S. Now, what have you done recently to prevent me from being able to rep you for the NATO.lua? :D

Edited January 18, 2012 by effte

[tflash]

A small question @speed: how did you deduce from my mission that it was 37T ? (in other words is there another way to know than tweaking the NATO.lua file?)

[Speed]

A small question @speed: how did you deduce from my mission that it was 37T ? (in other words is there another way to know than tweaking the NATO.lua file?)

 

Because 38T put me 600nm off the mark, and I also know that the boundry between 37T and 38T is right near where you put placed the mission at. I've added a tweak to the NATO.lua file to the mods section if you are interested.

[tflash]

Top, many thanks!

[bluepilot76]

Ive had the problem with 38T or 37T and was wondering if there was something I was missing... so is the gross error check the only way we can see an error? Its not on the map anywhere?

 

It can still be a problem in some missions where the targets could occur in a very large area. But I suppose that is why some missions require knowledge of lat long entry?

 

Shirley this is catered for IRL?

[Jona33]

Ive had the problem with 38T or 37T and was wondering if there was something I was missing... so is the gross error check the only way we can see an error? Its not on the map anywhere?

 

It can still be a problem in some missions where the targets could occur in a very large area. But I suppose that is why some missions require knowledge of lat long entry?

 

Shirley this is catered for IRL?

 

You can use the altitude the JTAC gives you as a reference. When you enter the coordinates it jumps to where it's stored in the terrain database. If the altitude the JTAC gives you is much different to the one it jumps too try the other zone.

[effte]

You can mod your LUA files quite easily, as mentioned earlier in this thread, to add the grid zone designator. Speed posted the mod over in the mods section.

 

In real life, the GZD is given unless there's absolutely no chance of omitting it causing a misunderstanding.

[Speed]

Yea, this mod here: http://forums.eagle.ru/showthread.php?t=84409

will make the JTAC give the UTM grid zone designator.

[bluepilot76]

Ah ok good I will see if I can do that. Any Qs I will come back. Normally consider this sort of thing above my level but managed to edit the labels the other day without causing the computer to meltdown so I will have a bash!

Thanks!

[hassata]

You can also slew the MFD cursor to the approximate position of the JTAC and note the coordinates at the bottom, no?

[effte]

Only you don't know where the JTAC is at*, or if the JTAC and the target are in the same grid zone.

 

*) JTACs are to never give their own coords over the radio, under any circumstance. Hard-learned lesson.