Advanced TMA help
 

I've been practicing advanced TMA against a known target (speed and course checked in the mission editor) and I think I could use a few pointers in refining my solutions.

Here's a pic of solution I worked out.

http://www.xl-logic.com/mobo/tutoria...20070723_1.jpg

For starters I set my range circle to 20KM as I think that's the known range where the sonarman will start reporting contacts. I begin taking bearing readings every 5 minutes for a total of 25 minutes of which I plot in Mobo. Once I work out the target's course I predict where he'll be in the next 15 minutes. From there I jet off in another direction (I think it's called across the line of sound?) for 15 minutes and then stop to take another bearing. From there I should be able to triangulate the target's position.

The red contact marker shows my new position after my 15 minute run and the red circle denotes the triangulated position. Am I correct so far? If that is indeed correct my next question is how do I determine the target's speed just from that triangulation?

You know the target heading
You know the bearing of the target at T-00
You know the bearing of the target at T-40
You've triangulated the target position at T-40

With that, you can plot the TC (true course) of the target. You can measure the distance the target traveled over its TC and use Distance and Time to determine speed.

Here's your work so far... (it appears correct, TMA solution seems reasonable)
http://www.xl-logic.com/mobo/tutoria...20070723_1.jpg



You triangulated the target position, so plot a contact on the triangulated location.
http://www.xl-logic.com/mobo/tutoria...20070723_2.png
Notice above I added a node and connected Contact to Node so I could make sure I was gettng the TMA heading solution of 305° accurate. I entered time for the contact as 40 and I plotted the node at the T-00 bearing.

Now when I use the TSD feature (hover mouse over contact and press Y key), MoBo shows the time elapsed and solves for target speed.
http://www.xl-logic.com/mobo/tutoria...20070723_3.png
The TSD solution calculated 6.5 knots as the contact speed.

MoBo knows the distance travelled for any plotted line, let's display it for ourselves...
http://www.xl-logic.com/mobo/tutoria...20070723_4.png
So between T-00 and T-40 the contact travelled about 8000m.

MoBo was doing the nomograph work for you, but since you've got it there, let's draw the line to determine speed.
http://www.xl-logic.com/mobo/tutoria...20070723_5.png
Drawing the line on your nomograph for T-40 and 8000m shows 6.5 knots.

Good news is, you can probably continue your advance submerged and catch the contact. ...as long as your speed is at least 5 knots.
http://www.xl-logic.com/mobo/tutoria...20070723_6.png

Sweet!

Thanks a bunch aaronblood.

If you should happen to continue practicing and maybe eventually using it on a patrol, report back and let us know how you're doing with it...

Probably not too many that actually use the TMA tool for passive attack approaches on 100% (and by 100% I mean 100% and no map updates).

Not sure why the GWX guys decided to tweak the no map updates setting so it wouldn't effect the realism score... they should put that back the way it was so when people say 100% they really mean 100%. I could see maybe doing it if the hydro-contact line didn't terminate right at the target's exact location...

When tracking targets at long range, 5 minute intervals aren't usually long enough to show any significant bearing changes. Could you take bearing readings at say, 20 minutes, and then as time goes by and the bearing changes become greater, go down to 15 . . . 10 . . . and finally 5 minute intervals? As long as I enter the appropriate times for each bearing mark, Mobo won't care if I tracked the target at irregular intervals?

If that won't work what do you do for tracking long range targets where there's very little bearing change using 5 minute intervals? Do you just wait for the target to get closer before you begin to plot bearings for TMA analysis?

The TMA tool, as it is now, requires equal time intervals in order to work... Although, you raise a good point. Might be more useful to have the option to automatically adjust to variable time intervals.

I'll have to noodle on that one a bit. It would require a modification to the existing TMA tool or a new tool, in either case I'd have to release a version 1.1 to include something like that.

For now, you could take your first bearing, and monitor movement over 5 mins, if you don't see enough of a change wait for 10... if 10 is better use 10 minutes as your observation interval. MoBo doesn't care what you use for a time interval, it just has to be an equal time interval... but I don't think the logic would be too difficult to use a variable time interval as a ratio multiplier. :hmm:

Of course, if you used your own intuition, nothing is stopping you from taking 10 min intervals for 3 observations and 5 minutes thereafter. Your line stack would be in two distinctly different segment lengths, but you could certainly reason that out easily enough.

Tried out TMA the other night after seeing this thread and having a better idea of how to go about it.

It was one of those "holy sh!t it actually works!" moments :D

:rotfl:yes those fantastic moments :yep: