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Old 02-01-12, 11:39 PM   #2
razark
Ocean Warrior
 
Join Date: Mar 2007
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Quote:
Originally Posted by gi_dan2987 View Post
...obtain two range/bearing readings...
How much time do you allow to pass between readings? I think that the estimate is better the longer you wait between readings.

Quote:
Originally Posted by gi_dan2987 View Post
Now when I use map tools to plot stuff, there's a margin of error there too, which doesn't affect the course so much as the differences in range throws the speed calculations way off. Is there any way to obtain accurate speed estimates?
If you're plotting it out, use more than two data points. I usually get a fix at 0:00, get another fix at 3 minutes, another at 6, then 10 minutes, with a fix every 5 minutes afterwards. If I detect a zig, I start over with three minute plots. I usually base a speed estimate on 15 to 20 minutes of plots.

I also enter everything into the TDC, and check to see how well the data matches with observations. If you've got a good idea of his course, that can help you refine the target's speed. I don't know what mods you might be running, but I love the 3D TDC mod for this.
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