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Old 11-27-11, 04:17 PM   #1
jcope
Bosun
 
Join Date: Dec 2010
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Default Suggestion for a Simple Enhancement to Improve Accuracy

I assume MoBo is still being enhanced. It is a great tool, and I enjoy using it. If you aren't still working on it, then never mind. But here are my thoughts...

Whether you are moving or stationary, using TMA to derive the direction of relative motion is very sensitive to the accuracy with which you can take the bearing at a given time. The method I see described most often is to take bearings repeatedly over a fixed time interval and then solve the problem graphically, which in MoBo means trying to get the little red lines to be the same length. Technically this equates to finding a course which crosses the bearing lines such that the distance moved by the target over each interval is the same. Because the time is the same, then the distance must also be the same, assuming constant speed and course of the target. There is only one target course that will solve that problem.

Mathematically, taking bearings at a fixed time interval is not required. Time is accounted for in the equations. The fixed time interval is just a convenience in the plots.

But what this means is our task is to pick a time and measure the bearing at that time. In the game, we can measure time precisely to the second. We can measure bearing somewhat precisely and only to the degree. If I pick a time interval of, say, 10 minutes, that gives me time resolution of 600 seconds. It the target is distant or slow moving, I might get a bearing resolution of 7 degrees. That low bearing resolution means my accuracy is going to be low. For TMA to be accurate, I need higher bearing resolution. I could guess to the half degree, but that's a guess, and I end up just adding my own errors to the mix.

I would be much better off predefining a precise bearing and letting the time vary. I can concentrate and put the reticule exactly where I want it, taking much of the guesswork out of figuring out the bearing. Taking precise time at which the target crosses that bearing is trivial. The accuracy of my measurements has gone up.

If MoBo would account for varying time between bearings, I would be all set. DRM results would be more accurate. That would be simple, I think.

Example: I take three bearings. Bearing 1 is taken at time 0. I then position the reticule on a bearing of my choice, as precisely as i can, and bearing 2 is recorded when the target crosses the reticule which occurs at time n, measured to the second. I re-position the reticule similarly ahead of the target, and bearing 3 is recorded at time m. Plotting this in MoBo, i would have the right course when i have positioned the intersecting line such that little red line 2 is m/n times the length of little red line 1. The software knows the times I put in for the observations, so it could give an indication of when I've positioned the intersecting line correctly. Either it could scale the little red lines, or put a number readout next to each one that would help.

Just an idea. I get the impression there isn't much going on with it now. With or without this, it's a useful tool.

But I think this would solve two problems: 1) the accuracy problem I already identified, and 2) the need to sit stationary and do nothing while a potentially fast moving target passes by so I can get better accuracy by increasing the number of degrees between readings. Not to mention, the longer I wait, the more likely it is that the target will change course on me, wasting the whole TMA effort.

Thanks for reading.
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Old 11-29-11, 08:27 PM   #2
XLjedi
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Join Date: Jun 2005
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There was a point in time that I was considering a modification that would allow the TMA tool to "read" some sort of time input for the various bearings. Not sure why I didn't follow through on it...

On the other hand, the TMA tool as it is might be a little more appropriate for the time period (mimics a sawtooth speed gauge). Which is still within the technology parameters for the time period.

I'll take a look at it...
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Old 01-28-12, 03:37 PM   #3
flopers88
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Thanks a lot for this help in Mobo tool to improve accuracy, it helps a lot to me.

Cheers!!
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