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: New ways to create false horizons?
    From: Don Seltzer
    Date: 2017 Jul 21, 10:35 -0400

    On Thu, Jul 20, 2017 at 6:13 PM, Pete Solon Palmer <NoReply_Palmer@fer3.com> wrote:
    Maybe there is an electronic AH solution.  The sensors (mag, gyro, accel, gravity) in my smart phone seem to be less accurate than a ball bearing and a toy compass, so I don't see a solution involving phones soon. 

    Ever since I took Frank's course I have been toying around with this idea.  Some years ago I developed some automated test stations for measuring performance of multi-axis MEMS  sensors such as those used in phones and other devices today.

    A two axis MEMS accelerometer is very plausible for determining the gravitational vertical.  The three main error sources are bias offset, scale factor error, and temperature drift.

    Bias offset is easy to deal with, and is conceptually similar to sextant index error.
    Scale factor error is a problem for measuring a wide range of angles.  When simply trying to determine a very small range around 'zero' angle it is of minor concern.
    The most challenging problem is temperature sensitivity of these devices.  Changing temperatures will cause all the other parameters to shift.

    Analog Devices is a leading manufacturer of MEMS multi-axis accelerometers, some costing less than $20.  I once did a rough error analysis of some of their devices and it seemed that it might be possible to achieve a resolution of about 1 or 2 arc minutes around zero.

    Don Seltzer
    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