TMA while moving problems

[XLjedi]

That's a good question.

What you've plotted is a nice DRT TMA track. I haven't had the time to add a MoBo tool that will give a solution like that (even though Dr. Sid has given me the code for it.) I guess I should try to incorporate Dr. Sid's least squares solution tool...

The TMA tool I have in MoBo presently is for working on a maneuvering board assuming you understand the concepts of relative motion. The plotting is actually a little easier (you only need half the nodes you plotted).

Here's your DRT tracking data: (true motion)



I'm interested in knowing the relative bearings for each observation:



Now here's how you plot it on a maneuvering board (relative motion):

It looks like 60° is a fair solution for direction of relative motion. I'm going to make a guess at a distance of 9000 yds for the last observation at 1535. You'll notice the diamond appears on the 9th ring of the maneuvering board.

I replace the TMA line with a contact and solve for the relative speed of 4.5 knots.

This is where the distance assumption can play into the speed determination. You were nice enough to tell me the speed was 7kts so I was able to backsolve for the 9000-8500 yard distance. If you don't ping for distance, or already have an idea of speed (maybe the sonar man says moving slow) then you would have to plot 2 or 3 more predicted bearings and then shoot off in a different direction for a triangulation.

Let's just say, that I was able to expertly determine the distance to target at time 1535 to be about 9000 yds. So, I now have my relative motion solution of 60°, 4.5kts.

Now I add the contact RM vector to my ownships vector and...

...I get a true motion solution of 90° and 7.2 knots.

So Captain, target bearing True 1°, Rel 236° at 9000 yds, course 90° at 7.2 knots. Probably a good enough solution to score a hit I think.