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Ground balance is not discrimination at all. Setting the ground balance eliminates background noise and has no effect on targets. Discrimination allows you to eliminate selective targets from your responses. That's a big difference right there. The actual method for accomplishing each is also vastly different.

A waveform return with ground balance will eliminate the background noise of the non-target response. The discrimination circuitry eliminates the target by notching out selected target responses from the waveform.

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You posed that question to me already and I dodged it on purpose. However, asking it twice gets you the technical answer. The phase shift of a background of magnetite is constant while the phase shift from a chunk of it is not. Even if you eliminate the magnetite in the ground, you will still find a large chunk of it if you don't have your discriminate set. You see, when a mineral is in the ground it is usually there for a great area at a relatively predictable density. That means the phase shift is constant over the range of that mineral which could be miles or merely yards. Ground balance shifts the fundamental frequency to match the shift. It doesn't take much but it does eliminate the false return from the ground or a hole - if it's set right.

Ground balancing is not discrimination but if it helps you to understand it, then think of it as if it is. It really is only mildly related in practice and markedly different electronically.

Look at it this way. If they were the same, why have two methods for controlling it? Because they are not the same. That's why.

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GoldDigger1950, outback;

You have both confirmed for me what I had reasoned, without the technical argument, that is:

IF I am looking for variations, in ground variations (of magnetite,) do not use ground balance!

Mapping the magnetite, in a gravel bar works, no matter the technical arguments, I have observed it in action (with a BFO too) where a friend mapped the edge of a concentration, marking it with coloured flagging. Then he proceeded to recover the gold, contained in that concentration.

The home-built BFO, did not have ground balance nor discriminate, obviously, and the gold was not detectable, being masked by the magnetite, as you have suggested.

Does anyone know the effect of ilmenite, on detection?

goldigger



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GoldDigger1950;

A couple of hints... but I don't know SG, offhand:

greenish black particles similar to magnetite but dull looking, as big as 5mm X 3mm, possibly bigger;

weakly magnetic;

a compound of titanium, but heavy;

persists with black sand and garnets;

is used as a filler for drilling mud, as it wears longer than most material;

the ore of titanium.

Try Googling.... if I had some separated, I could send a sample. Some day surely. How much you need to play with?

goldigger



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goldDigger1950;

NOT DIRT!

And I might pick out as much as a cup from 3 - 4 litres of black sand... oh, I see, you want just the gold not what it comes in.

Bet Oz doesn't have ilmenite, you could have to pay for importation. 

I consider it valuable dirt, because there is fine gold in the black sand.... it would have to be leached out, it is that fine. Actually it is fairly easy to separate from black sand, the magnetite holds a residual "charge" of magnetism and will clump to itself and wash away, leaving EVERYTHING else.

When I get too much saved, I will have to do something about it. 

goldigger

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