[REL] Tutorial for tracking with sonar

[jerm138]

I've been thinking about this (probably too much) and I realized that you were partially correct in your original post, Aaronblood...

The concept I presented is still correct: The intersecting line that produces equidistant segments will give away the ship's course (and range if you have enough data) BUT .... (and here's the part where you were correct) the way you find that line will not be the same as if you're sitting still. You can't just move the first reading over then draw intersecting lines... it's more complicated than that for dynamic data.

I have to look into it further to see if there's a way to find that magical line with equal segments with data taken while you're moving.

Thanks for second-guessing me on it and making me think about it more. Back to the drawing board...

[XLjedi]

Actually I dunno...

(funny how we're arguing on behalf of each other now )

After I typed that response (early this morning) it dawned on me that I was thinking in reference to a relative motion plot on a maneuvering board where all lines would radiate from the center.

In your case, you're plotting bearings on a DRT (dead reckoning tracer). The inherent motion I was thinking about I believe is accounted for in your update of OwnShip's position. Your plot looks more like the TMA lines in Dr.Sids Least Squares TMA solution example rather than one of my relative motion examples.

In MoBo there is a TMA tool that will do the measuring between the lines to help determine the target TC. Would you mind if I worked up an example or two on MoBo? ...for the benefit of those who like to use it. Of course, it would be even better if I could enlist you to do it for me.

Your example and Dr.Sid's original examples are both currently not represented with tutorials in MoBo. However, since MoBo is both a DRT and a Maneuvering Board, it is perfectly capable of handling the technique.

Incidentally, what graphics program are you currently using to create your tutorial images?

[jerm138]

I've never used MoBo, so I'm not sure I'd be much help there. I didn't even know it existed until this thread.

If you could come up with a way to prove or disprove this method, that'd be great.

I know the part about an intersecting line with equidistant segments is correct. The only part that would really need tested is the method for finding said line when OwnShip is not stationary.

For my tutorial images, I'm just using PowerPoint and exporting to .pdf. PowerPoint is an excellent vector drawing tool if you know how to use it. I'm a vector-art fanboy... raster doesn't cut it for me. I've tinkered with powerpoint for many years and I've made some pretty complex images with it. I even used it to re-make Cap'n Scurvy's AoB circular slide rule. I posted pictures of it here. It comes in pretty handy.

[XLjedi]

I don't think it needs further proving or disproving... However, I could easily prove that a two-legged series of equidistant observations while moving will yield a correct solution for true course.

I need to review Dr.Sid's logic now. There was a time when I was considering adding a least-squares TMA tool to MoBo, and I just haven't gotten around to it. I think Sid's least-squares method didn't even require that the observations be spaced at equivalent time intervals. On the one hand, that's pretty cool, on the other hand, purests might argue that the method would require more sophisticated computing power than may have been available at the time.

Your example strikes a nice balance in that it appears to be a valid TMA solution using methods that could have been employed with the technology available to tracking parties of the WWII era.

If you like, I can post a single MoBo image that will simply prove the concept works. If there is any interest from people wanting to know how I did it, I can follow up later or perhaps on another thread with more detailed MoBo instructions.

[XLjedi]

PowerPoint?

The only vector drawing tools I see in PowerPoint are the same lame autoshape and drawing tools that are available in Excel.

Are you saying you used those tools to create that AoB dial?

[jerm138]

All I'm looking to do now is to find that "magic line" using the conventional in-game tools.

I racked my brain with it all day at work. Knocking down some geometry cobwebs. I'll get it eventually.

Yes, my tutorial, and that AoB calculator were made in Powerpoint. They're the same drawing tools used in most MS Office programs. They're definitely not lame once you learn how to use them... I even used powerpoint when kicking around ideas for my next tattoo! (It's a cover-up for a Batman symbol)... but I think I'm going to scrap this one and go with a more photo-realistic approach.

[XLjedi]

I thought it would take only one pic, until I plotted this first one and it didn't happen to work so perfect.


In this case we see that a 30° course change away from the hydro bearings would produce a fairly decent representation of target heading but the distance in this case remains ambiguous.


Turning 30° into the hydro bearings produces a better result with a little more certainty on distance.


The best results are achieved with more aggressive turns into the hydro bearings that result in lattice-type contact bearing lines. Here we can see the TMA tracking tool lines up best when overlaying the true target track. Of course the only problem with this is that if you maneuver your sub until you get lattice bearings, you will most certainly be left in a poor position assuming the very slow submerged speed of WWII era subs. You may then be stuck doing a surface run end-around.

Do you want me to post one for constant OwnShip heading with increase-decrease speed?