> That's why you do not use the earth field, instead you swamp it using a
> strong field of your own from a pm, besides the magnetisation/readout
> coil. This causes the precession frequency to be higher than usual for
> these instruments.

Yeah, I know.  In fact, the post that followed gave a full description of
how to implement this.

> Why would anyone try to use this expensive and complex method to detect
> water I don't know.

Frankly, as this list has many hobbyists on it, why not?  It's not as
complex as all that... A magnet, two coils, an oscillator, a power amp, a
preamp, an opamp integrator, and a micro...

process is: send; receive; measure; reset

I doubt that this is too much more complex than either sonic coupling or
microwave absorbtion...

The clear winner from my perspective would have to be Roman's thermal
conductivity.  The NMR method just interests me.  I work with it, and am
surrounded by people who understand it well, so it's an interesting idea to
me.

--Brendan

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