NavList:
A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
From: Paul Dolkas
Date: 2015 Jul 1, 09:42 -0700
Dave-
That may just be it. It’s the normal AC power lines that seem to be the problem.The electronic compass I am referring to is part of a wristwatch. I don’t think the designers really cared about accuracy, rather just a general sense of where north is. Plus, they are probably completely out of room for such refinements – the same watch has a barometer in it as well as all the usual watch stuff.
Paul Dolkas
From: NavList@fer3.com [mailto:NavList@fer3.com] On Behalf Of David Fleming
Sent: Tuesday, June 30, 2015 9:27 PM
To: paul@dolkas.net
Subject: [NavList] Re: Hand Bearing Compass Deviation
Magnetic Fields are horizontal virtually nowhere on the earths surface. They have dip, ie point also in a vertical direction as well as horizontally.
When you speak of near power lines do you mean seeing interferrence from AC or DC power lines. It is likely that needle compasses do not have high frequency response so they would not be sensitive to 60 cycle- this is speculation needs to be verified.
Flux gate compasses use 10s of KHz signals to sense the magnetic field. Obviously their designers are aware of this so I would expect they filter and diesign with 60 cycle interference in mind, so who knows.
Dave F
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