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
    Automatic deviation calculation by electronic compasses
    From: Joe Schultz
    Date: 2009 Nov 24, 10:44 -0800

    Yes, George, US Navy ships are made of steel.  Very, very special steel.  Just 
    kidding - I don't do the "look at me I'm so smart" game.  My posting (10801) 
    was in response to your "It's always possible that I've misunderstood the 
    technology, and the makers have some clever trick up their sleeve that I've 
    missed. If so, no doubt some list member will put me right" in post 10794.
    The advantage of these "electronic" compasses is that you can put the sensor 
    assembly anywhere you want - no need for "Navigator's Balls."  Find the sweet 
    spot and put it there.  Then, if needed, punch in an offset (this for the 
    high-end, i.e. expensive equipment).  Doesn't fix the three major drawbacks: 
    1) eliminating the vertical component of the magnetic field when the vehicle 
    is heeled, 2) moving in a circle to calibrate, and 3) effects of an 
    alteration to the ship's configuration, i.e. additions or deletions of 
    equipment, unless you redo the offset.
    1) is reduced through gimbaling (two axis systems) or by using a third axis 
    sensor and then "calculating out" the vertical component.  A third sensor 
    leads directly to "why bother?"  Three magnetic sensors and a computer or 
    three accelerometers and a computer (inertial).
    2) has been partially solved by an engineer at Delphi, an automotive industry 
    parts supplier - they do the automotive "electronic compasses."  With his 
    system you move in a partial circle - the electronics assumes an ellipse and 
    calculates the ellipse locii.  The locii location, in relation to the curve 
    location, determines the quadrant.  It's patented, so the rest of the 
    suppliers will have to wait it out or devise their own system.
    3) is not a factor in an inertial system.  "Why bother" won for US Navy ships.
    NavList message boards: www.fer3.com/arc
    Or post by email to: NavList@fer3.com
    To unsubscribe, email NavList+unsubscribe@fer3.com

    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