Welcome to the NavList Message Boards.

NavList:

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

Compose Your Message

Message:αβγ
Message:abc
Add Images & Files
    or...
       
    Reply
    Re: New ways to create false horizons?
    From: Brad Morris
    Date: 2017 Jul 23, 20:45 -0400
    Don

    There are plenty of encoders available, with very high accuracy.  One only need mount it concentric to the index arm axis of rotation.  Directly encode the motion of the index arm and eliminate all gearing, similar to a vernier sextant, only with a direct readout of D.M.S.

    Brad



    On Jul 23, 2017 2:25 PM, "Don Seltzer" <NoReply_Seltzer@fer3.com> wrote:
    On Sat, Jul 22, 2017 at 9:33 PM, Pete Solon Palmer <NoReply_Palmer@fer3.com> wrote:

    Just to throw up ideas for everyone to knock down:  The rotary encoder seems to be rated by resolution per turn.  In the sextant we only need 1/4 turn so maybe we could gear it up 1:4 to increase the rez?   Cons would include the complication of gears and gear lash.  Linear encoder is lookin' good.  Maybe have a low rez solution for degrees and a higher rez for the minutes?

    I suspect that gearing would create both accuracy and backlash problems.

    There is a type of rotary sensor that can be electronically 'geared'.  Resolvers are a magnetic sensor, sort of a rotary transformer.  Very rugged and no backlash.  A simple resolver generates a sine and cosine signal over a single revolution.  The ratio of the two can be used to determine the angle, typically to one part in 4000. There are also multispeed resolvers with multiple pole windings that generate a few sine wave cycles in one revolution.  With a 6X resolver, one could resolve a full revolution to one part in 24000, good enough for one arcminute.

    It is has been decades since I worked with them, and I have no idea how available or expensive this technology is today.

    Don Seltzer

    View and reply to this message

       
    Reply
    Browse Files

    Drop Files

    NavList

    What is NavList?

    Join NavList

    Name:
    (please, no nicknames or handles)
    Email:
    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:

    Email Settings

    Posting Code:

    Custom Index

    Subject:
    Author:
    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