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    Re: Fix Maximum Probability Positions
    From: John Karl
    Date: 2013 Mar 24, 20:22 -0700

    Yes, yours is a common definition of DR position, using only course and speed. I tried to make it clear in all my discussions, that the DR position I was using was the best estimate the navigator had, or chose to have.

    Then the recent LOP, having much greater accuracy than the dead reckoning "DR" point, is to be given greater weight is fixing the upgraded position. With no other info, the MPP would be on that latest LOP at the point nearest to the "EP." The older LOP is not used at all in this plot; it played its role in forming the origin of the current DR run.

    Your experience on runs of a few hours was excellent, giving very little disagreement between your "DR" and your new LOP. Over longer runs (days?) and highly variable conditions this might not be the case. The whole point of the EPRF is that it gives the best position under all conditions, including all angles between successive LOP pairs. Plus it gives a realistic quality check on the dead reckoning. Since it's even simpler to plot, I don't see any reason to use the traditional RF.

    Fair winds,
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