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Steve Herschbach

Fisher Impulse AQ Discrimination Explanation

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Please read the posts Dew...I linked directly to the discussion of the 1c, 2c, and 5c Euro. First link in my last post and the discussion prior to it at that link. There is even a picture of the coins. To be honest, you have so many questions because you don’t follow the entire discussion and ask questions answered before. It’s like the small gold salt thing... I’ve tried to explain it to you before but you go on hoping and asking again when it is a futile hope. No matter who you ask or how often you ask the answer is always going to be the same. Tuning out salt tunes out small gold.

For me there are almost zero questions left about the Impulse AQ. Except for silly stuff like will it leak? 🙂 But the performance parameters have been pretty well laid out already as far as I am concerned. I suggest you go back and read everything over from the start in the last half dozen threads.

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You can’t separate small gold from saltwater using conductivity as your basis. Period, end of story. My hope however had been that on the dry beach the Impulse AQ at 7uS would have exceptional small gold capability and maybe even do well nugget hunting in low mineral ground. That hope was dashed. The minute I asked this question and got this answer I knew it was not to be. The Impulse AQ like the CZ-21 is locked into full time salt mode, even in all metal mode. It truly is designed specifically for saltwater use and specially targets the ring range at the exclusion of the salt/small gold/small aluminum range.

It appears the 7 uS design is intended to boost ALL signals prior to processing. You can’t process what you can’t detect. Then unwanted signals are removed. First, ground and salt in all modes. Aim for stability. There goes small gold. Then add disc to take out most small and large ferrous leaving the gold ring “sweet zone”. That eliminates lots of targets like high conduction coins, silver rings, and large high purity gold rings if you set the disc aggressive,y. The tipping point is somewhere around zinc penny. The emphasis on both salt and black sand elimination at the expense of small gold sensitivity should make for a stable machine.

It turns out the 7 uS spec was not intended as a way of finding small gold with the Impulse AQ model. That was just an assumption on the part of myself and others that has proven incorrect. It will no doubt be implemented for that purpose in the gold prospecting model, which will get rid of the salt elimination and disc modes in favor of small gold capability and variable tuning for highly mineralized soil and hot rocks. 

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Let's not OVERTHINK this detector.  I remember Rick pointing out that this is a very simple detector.  Maybe not as simple as a Whites Dual Field but still simple.  Where the OVERTHINK comes in is that since we don't have one in hand we are still trying to compare it to VLF detectors.  Steve has pointed out that we can ONLY compare it to other PI detectors.  Again, most are pretty simple with very few controls.  Mode control on the Impluse is about as complicated as it gets.  The charts are pretty simple to understand (unless I am over simplifying them), reject the differ size nails and you reject different denominations of Euros. Again, they are in France and can only compare Euros with the nails.  It is also stated that the shape of the coins verses the shape of the nails will cause a double beep in the nail and not in the coin on depending on the mode that you are detecting in.  It has been stated several times that Le Jag almost always prefers to hunt in All Metal where nothing should be rejected except for saltwater which is always rejected as it is a built in feature which again makes this a simple machine as it is one less thing for us to fiddle with. Once he acquires a target then he will change Mode to decide whether or not do dig the target. 

Now if I am underthinking this detector please let me know.  I read posts  and think, "Is it me not understanding or is it others making it more complicated?".

Just my two cents,

Joe

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Well with apologies to Dew and in defense of the overthinkers (I’m one myself) the whole reason for a forum is to ask questions and discuss things. I guess where I have a hard time though I endeavor to be patient is when questions are asked that were answered earlier on the very same thread. People don’t read through, they jump to the end the ask the questions again. But that’s ok. It’s just the nature of the medium and people being in a hurry. And some stuff is complicated, like how disc is implemented in a PI detector and how it differs from a VLF. Bottom line is it is a job I took on myself to set up and moderate a forum and I’ve got no right and in fact am stupid to complain when people ask questions and discuss things. It is the reason the forum exists.

So I do apologize Dew... your questions are welcome as are your contributions to the forum.

That out of the way.... yes, I agree with you Joe! :smile:

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I think in a few weeks we will all be fluent.Some peeps are really good as memorizing functions and panels .Sometimes by heart they can advise you on the phone remenbering the settings or even a whole program.I am absolutly rubbish ,perharps because i am using few different machines.........

Lets Pulse peeps😎😎😎

 

 

RR

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No problem Steve.   I did investigations In the Army and was a Magistrate ... so I do tend to ask way more than needed.  So no need to apologize.  

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Simple is better. My only concern with the AQ is going to be setting it up properly to hunt. I'm an end user. My mind cannot wrap around all the different aspects as it relates to detecting technology. I'm constantly amazed at folks like Steve who can not only understand all this stuff but also explain it in such a way that people like me can go " ok, do this now go hunt." If I miss the occasional small gold but still get 90% of the other gold sitting in the wet sand I'm going to be happy.

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On 1/9/2020 at 6:38 PM, Mike Hillis said:

hmmmm.

How small of an item can I go down to with 7 ns pulse delay?

HH

Mike

I have already found a ring of 22k 0.3 grs

I think 0.2grs 18k  and 0.1grs 14K

The chains in 18k it depends on the size of the mesh
In 14K it's much easier but here we don't have any, it's only 18k

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Skate.... now I wonder out of that 90% you are getting... how much will other machines hit?   BUT ... reading the weight just mentioned it’s going to grab better than an Xcal I believe.... smallest gold chain last year was .3 grams with the Xcal.

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2 hours ago, dewcon4414 said:

Leads to more questions so ill stop asking ...... lol,  but thank you Steve.   But ..... what is 5C, 2C and 1C?

They are coins from here in Europe.  Its appearance seems to be copper, but nothing is further from reality.  Its material is highly ferrous and as I have put in the photo when they get lost on the beach they are not worth even for the legal course.  When I had TDI SL you had to dig it if you wanted to recover gold and it was frustrating to make 12 or 13 inch gaps and get that out.  The beaches of southern Spain what I live in are full of these coins

20200111_211946.jpg

20200109_113738.jpg

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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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