Welcome to the NavList Message Boards.


A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding

Compose Your Message

Add Images & Files
    Re: The Darn Old Cocked Hat - the sequel 1
    From: Hanno Ix
    Date: 2013 Mar 15, 15:52 -0700

    You are far ahead with your MPP. This is fast!
    Of me, anyway.

    Do I understand your second plot right:
    In the text, you call the second figure a histogram.
    It appears to agree that the estimated probability
    of a certain distance is zero. 

    Could you please specify that distance ( from to ?) more closely?



    From: Andrew Nikitin <nsg21---.com>
    To: hannoix---.net
    Sent: Friday, March 15, 2013 1:18 PM
    Subject: [NavList] Re: The Darn Old Cocked Hat - the sequel 1

    I made computer simulation of the fix taking on board "Barack Obama" aircraft carrier.
    In my model:
    1) There are 10000 navigators (100 would not give as clear picture).
    2) All navigators are clones and use identical equipment, which enables them to perform altitude measurement with same ?=1'
    3) They all shoot same 3 stars (azimuths shown on diagram with 3 short blue lines)
    The gray-ish area is a distribution of fixes. Each dot is MPP obtained by
    individual navigator. For example, red triangle shows 3 LOPS obtained by
    navigator 5575 and red marker shows location of a symmedian (which is MPP of
    choice for this navigator) of the resulting cocked hat triangle. Green triangle
    shows MPP and LOPs of another, in some respect luckier, navigator 9161. Note
    that true location is not inside cocked hat for navigatore 5575 and is inside
    cocked hat for navigator 9161, despite 5575 having both smaller area triangle
    and having closer to true MPP.
    The slightly elliptical shape of distribution depends on the choice of
    azimuths. Azimuths intersecting at 60° will yield perfect circle.
    The second diagram shows estinmated proability distribution as a histogram of
    0.25 mile distance buckets.
    As Gary explained the hump in the middle is explained by the fact that this
    probablity is a product of 2 functions, one grows linearly with distance (this
    is area of a ring another quickly decreases with distance (could be just a
    normal distribution, not sure about it. The situation is muddied by the fact that this second function depends on direction, so you need to integrate across all directions, but this does not change basic principle)

    NavList message boards and member settings: www.fer3.com/NavList
    Members may optionally receive posts by email.
    To cancel email delivery, send a message to NoMail[at]fer3.com

    Attached File:

    Attached File:

    View and reply to this message: http://fer3.com/arc/m2.aspx?i=122884

    Browse Files

    Drop Files


    What is NavList?

    Join NavList

    (please, no nicknames or handles)
    Do you want to receive all group messages by email?
    Yes No

    You can also join by posting. Your first on-topic post automatically makes you a member.

    Posting Code

    Enter the email address associated with your NavList messages. Your posting code will be emailed to you immediately.

    Email Settings

    Posting Code:

    Custom Index

    Start date: (yyyymm dd)
    End date: (yyyymm dd)

    Visit this site
    Visit this site
    Visit this site
    Visit this site
    Visit this site
    Visit this site