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    Re: 3-Star Fix - "Canned Survival Problem"
    From: George Huxtable
    Date: 2008 Jun 14, 07:39 +0100

    GregR wrote-
    > Hmmm... just had an idea - I'm going to go back and "massage" all 3
    > sights with Navigator to make them overlap perfectly (i.e. zero
    > intercepts) and then plot those LOPs - maybe that'll help point to
    > where the error in my rough plot is coming from.
    It dawned on me that "zero Hs error" is probably a better way to say
    that than "zero intercepts" (I use Navigator to check the accuracy of
    my own sights, and using a known GPS position as the Assumed Position
    the intercept from that position becomes the error for that sight -
    hence in this case "zero intercept" = zero sighting error).
    And since the horizon wasn't clear the evening that I did the shots for
    the exercise, I also introduced some "dither" into the Hs values (via
    Navigator) to better reflect reality (and also to generate a cocked-hat
    for the fix vs. 3 perfectly crossing LOPs).
    So let me re-phrase that to say I'm going to go back and massage the
    earlier sights to reflect zero sighting errors so that (hopefully...)
    all 3 of them will cross at just one point - which can also serve as a
    plotting accuracy exercise.
    GregR is inadvertently demonstrating the value of exercises that actually
    represent reality, compared with exercises contrived to appear to do so.
    contact George Huxtable at george@huxtable.u-net.com
    or at +44 1865 820222 (from UK, 01865 820222)
    or at 1 Sandy Lane, Southmoor, Abingdon, Oxon OX13 5HX, UK.
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