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Steve Herschbach

Fisher Impulse AQ Discrimination Explanation

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1 hour ago, palzynski said:

Yes Alexandre and Steve , I agree with you , the more it is mineralized the more difficult it is to go deeper
this is what I wanted to say , probably I was not clear in my prev post.

Thank you Steve for the diagram , actually I did some measurements with a GPX4500 a few years ago and I could not get much than
13inches on a big coin in the air , a little less in my low mineralized ground. And you are right Steve this is not
far from a VLF machine which takes it at 12inches

But if we come back with the Manta video we are not talking about 13inches on a coin , but about 20inches which means a 54/100 increasement!
Even if there is a loss due to the mineralization , I would be happy with "only" 16 inches in my moderated mineralized ground,
this with a correct level of iron disc of course.

It looks like the AQ has something special to go so deeply, probably the delay to 7micros however I am
not a specialist.

For info , my VLF bed tests explained here :

Yes It's due to the pulse delay, and the noise signal ratio, the thermal stability...

This implies a physical mastery of materials, coil,board, layout, each track must be calculated to avoid jumps of magnetic fields....

When I lower the pulse delay to 2.2µs with the same coil current (not applicable to the range in salt water), at the output of the preamp I have 10 times more sensitivity (signal / noise) than today.

And at that moment you know that no other detectors will beat you up for the moment 😉

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Steve, 

At Rye Patch, NV. across the road from the burn barrel, one of Gerry's guys buried a nickle 18" deep and all the GPX units with an 11" coil can detect the nickle. I doubt if any VLF could see that nickle!😂

Bill

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GPX is a high power PI. When you get yours working in 6 feet of saltwater let me know! 😂

I always thought it odd the worlds largest manufacturer of pulse inductions detectors has basically ignored the waterproof PI market. The floats like a cork SDC with its hardwired coil really does not count. I always wanted a GPX 5000 stripped to salt mode stuffed in a CTX 3030 housing. Then we would not be having this discussion. As it is the GPX is in a class of it's own so far and great for those who want to use one on the beach but not in the water. Frankly I don't want a GPX control box anywhere near saltwater for extended periods of time, but that's just me.

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Steve,

Same here with my TDI Pro.  Maybe the HIGH water line but even that is not safe on a So Cal beach. LOL 

Joe

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18inches on a coin with a GPX I did not had these results it was rather 12/13 inches for me , this with the standard 11coil. But I did these tests a long time ago , 10 years ago and perhaps I should redo these tests. Also there is the GPZ that  seems to be more powerful than the GPX but its price is astronomic at 9000euros and no iron disc at all ...

Alexandre , yes it is not simple what you are doing , I thought that this was "just" electronics but it is more than this , so it takes times for the machines to be produced in an industrial way, this is normal. I am looking forward to see the AQ on the field during the coming weeks ....  

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PI detectors designed to run off 8 AA batteries are at a distinct disadvantage compared to high power pi detectors like the GPX. There is a reason for that brick sized Lithium Ion battery on a backpack. Here an ATX struggles to see an item at 18” the GPX sees with room to spare. And it is a die-hard Garrett dealer doing the test.

 

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      References
      Da Costa, A.C.S, Bigham, JM, Rhoton, FE, and SJ Traina. 1999. Quantification and Characterization of Maghemite in Soils Derived from Volcanic Rocks in Southern Brazil. Clays and Clay Minerals, v. 47, no. 4, p. 466-73.
      Hunt, CP, Moskowitz, BM, and SK Banerjee. 1995. Magnetic Properties of Rocks and Minerals. In Rock Physics & Phase Relations: A Handbook of Physical Constants, Volume 3.
      Koch, C.B, Borggaard, OK, and A. Gafur. 2005. Formation of iron oxides in soils developed under natural fires and slash-and-burn based agriculture in a monsoonal climate (Chittagong Hill Tracts, Bangladesh). Hyperfine Interact 166, 579–584.
      Rivers, JM, Nyquist, JE, Terry, D.O., and W. E. Doll. 2004. Investigation into the Origin of Magnetic Soils on the Oak Ridge Reservation, Tennessee. Soil Science Society of America Journal, Vol. 68 No. 5 p. 1772-1779.
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