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>Posted on 23 Oct 1996 at 11:11:35 by Alan D. Secor

>The type of magnetometer I have the plans for are a differential proton
>precession magnetometer.  The "sensors" are 2 inductors wound around 2 bottles
>filled with distilled water.  The coils are energized to align the protons, and
>then the coils are de-energized.  The coils are then switched into an
>oscillator circuit.  If there is no magnetic anomaly, then you will just hear a
>steady decaying tone.  If there is a pertibation in the magnetic field, the coi
>closest to the pertibation will very ever so slightly in inductance and you
>will get a beat frequency between the two.  The sensitivity is a function of
>the spacing of the coils and in the case of marine use, these are usually
>towed in a tow fish configuration.  To increase the spacing, Dalton suggests
>using a tow fish in addition to a surface mounted coil on the boat.  These
>types of magnetometers are generally much more sensitive than fluxgate.
>If you have anymore questions, I will have to dig up my documentation.


Thanks.  I understand how it works then but I am a tad pessimistic
about the sensitivity unless you can get a very high "alignment"
field on the protons.  Also, I would have thought it would be near
impossible to tune in to the narrow frequency range osccillation
with any kind of stability under less than ideal conditions.
With two sensors it might be a way around that.

So, my question is:  does it actually work in the field
(300 feet of water) ?

John

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