Detecting minute magnetic field changes

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Detecting minute magnetic field changes
<D.N. Scalbile>
11-08-2005

Re: Detecting minute magnetic field changes
Ben Bradley
11-11-2005

Re: Detecting minute magnetic field changes
Edward C. Kern
11-09-2005

<D.N. Scalbile> posted on
November 8, 2005, 6:50 am

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How to detect (open to friendly speculations) minute magnetic field changes
?

In application such as;
  * Detecting a crashed small aircraft in a very dense forest from another
small aircraft fliying at a hight of 1000-4000 feet  AGL.
  * Detecting  metal pipe 10-20m below in ground.
  * Detecting a small metal boat sinked to depth of 00-200m from  the
surface of the sea.
  * Detecting earth magnetic field variations from a low orbit atellite or
from a high altitude flying baloon.

Dave posted on
November 8, 2005, 8:31 am
Permalink

Re: Detecting minute magnetic field changes

lookup SQUID magnetometer

Dave

werty posted on
November 11, 2005, 9:22 am
Permalink

Re: Detecting minute magnetic field changes

A digital compass has a ferite core and 2 windings (  actually 3)
but the 2 are switched    off    then   on
as they turn on they are  effected by the earths mag fld .
and its easy to do for todays op amps are very good

BTW  Im writting a good OpSys for small
tings like robots . Later i'll expand it for large PC's
i call it NewForth .  Fits in 8KB .
also im hobbiing on ATMEL8515 and have a way to increase
the 4KB code space !  I use lists of addresses in SRAM to mimic
and increase the code space .

Ben Bradley posted on
November 11, 2005, 12:42 pm
Permalink

Re: Detecting minute magnetic field changes

The common name for that is a flux gate. I just googled, here's an
interesting article with a useful table of what devices cover what
range. As someone else posted, it looks like SQUID wins for the most
sensitive.

http://www.sensorsmag.com/articles/1298/mag1298/main.shtml