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5 hours ago, JCR said:

Your explanation of viscous mineralization verses ferrite. soil loss angles & the way these difficulties are addressed with Demod clocking and rotating the internal coordinate system is of special interest to me as I hunt in Maghemite soils most of the time.  In case I have missed something, can you direct me to the most pertinent parts of the book to best explain how adjusting the internal coordinate system effects things?  I am trying to better understand & utilize the Hot Rock adjustment on my Rutus Versa & the dt adjustment on my Nokta Legend. 

I think Ch 16 has most of the discussion on rotating the coordinates for ground balance. This is done for the broader matrix whether it is viscous (maghemite) or not. It looks like an overall loss angle and you adjust the R-axis (or G-axis, if there is one) until it is exactly 90° from the ground loss angle. Then there is no ground signal. However, this discussion applies to single frequency methods.

Hot rocks are just rocks with a different loss angle than the matrix. They can be higher (positive) or lower (negative). In a SF design a negative hot rock is pretty obvious, and a positive HR can often sound just like a metal target. The old SF models with HR reject (like White's) were 4-filter designs that relied on a "ringing" characteristic created by the concentric coil. I'm not sure that method of HR rejection would even work with a DD coil.

In an MF designs, the way you do things (GB, HR reject, iron reject) are quite different than how SF does things, and there are multiple ways to do it. I have no knowledge of how any of MF designs actually implement any of these methods (all in software) so I really can't help much. I will guess that they are probably looking at the response of the HR at different frequencies to distinguish it from a metal target, which looks different. Usually a HR adjustment varies the aggressiveness of the reject function, with the drawback being that a more aggressive setting might also reject some good targets. I view these kinds of settings like I do discrimination and pain killers: use it sparingly, and only as needed.

Sorry, wish I could offer a better response.

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Sorry, no. I looked into using an AI translator but it leaves a big mess that requires a ton of manual editing. This book has super-low sales numbers and I've already sunk 7 years into it.

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