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VLF Detectors- Discrimination Vs Notch


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I know this topic has appeared off and on over the years, but I'd like to better understanding on the theory and principle of using one over the other, ie. depth, and target id and what compromises do I induce.  The reason I ask is the new V4 for XP Deus has the ability to set a minus discrimination.  It kills the ability to use the "horseshoe" screen for ferrous target ID, but VID numbers are tolerable.  What theoretically happens if I set a negative discrimination, but use Notch to handle ordinary ferrous trash? 

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Depending where a person is in the world Notch Disc can be a dangerous thing, IE If I were to notch out pull tabs then I would loose 800 year old coins and some Roman coins because they share the same ID numbers, And another reason I don't like Notch Disc is because each Notch Block can overlap and wipe out good targets, Where as an Adjustable Disc allows you to set the point where the signal breaks, from trying to use a VLF for searching for Gold I have found that some Gold can signal such low ID numbers that you need to fine tune the machine right on the very edge of nails and no higher, where as the first Block on most machines will start around IE -20 to +10, which does not sound that high But a Gold and Platinum Diamond ring I found gave me a signal of around 4 so if I had been using block edits then I would never of found it,.

Block Edits can cover too wide an area per notch, So I would suggest that you use it as a last resort and when you do, Use it sparingly,

 

Hope that helps.

John.

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All you can do is try it. I generally prefer tones as the theory is that completely discriminating/blocking items creates a depth loss in adjacent VDI numbers. These days it all being digital it really depends on how well the system is designed. DEUS V4 being so new I doubt very many people have real answers yet.

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Steve,

I see your point on using a specific tone assigned to typical goldfield trash rather than true discrimination.  Running zero or even negative discrimination then setting the range of typical goldfield ferrous trash to the lowest tolerable tone, gold and other non-ferrous come in at a user preference higher pitch tone.  Sounds good in theory.  A great place to try it would be that hydraulic pit we hiked summer before last.  

Hopefully we see the new elliptical coil before I leave for N. CA.  My trip has been delayed for a couple weeks.  I should be up that way by the end of June now. 

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Will be interesting to follow your experiments with discrim, notch and negative discrim. I have put off getting a HF coil until the elliptical arrives and can see XPs method of attacking ground noise and trash is exciting stuff. 

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