Pulse Induction Discrimination 20 Plus Years And No New Breakthroughs

[VicR]

Used my Schonstedt in Gusap, Ramu Valley , Papua New Guinea on world war 2 USA / Australian air fields. Had to get a back hoe digger in on one target - proved to be a dump of parts from US trucks and not the  jeep rumored to be buried around that area. Just proved how deep the Schonstedt could go on large ferris targets. The guy with the white t shirt is holding the Schonstedt.

 

[GB_Amateur]

My skeptic detector is ringing up louder than this guy's magetometer.  What's a 'CCR'?  On max sens, the farther he moves the tip from the CCR, the stronger the signal gets.  IMO he's actually picking up other stuff (maybe some iron is his pockets, etc.)  Obviously this device works at some level, but this video has the usual confirmation bias of the user.  Ugh.

 

[Chet]

The guy in the video is new and doesn’t yet understand the proper use of his new detector. He is flailing around too much to get proper response to targets.

Here is more on how it works;

https://www.youtube.com/watch?v=sTFIUyL0-Ow
 

[Steve Herschbach]

3 hours ago, VicR said:

Just proved how deep the Schonstedt could go on large ferris targets.

Yup, if huge ferrous is the problem, like axe head and larger, mag is great. But again, good luck with the nails.

[Aureous]

I had an occasion where on a well-known big nugget patch at Bendigo back in the late 90's, I got a soft Ch1 signal and I got instantly excited. I knew it was deep...... I swapped my 11" mono on the SD2200 to the old stock 11"DD once I got down a foot or so just to see if discrim knocked it out. Nope, it was still 'boinging' away and getting louder. I widened the hole until I was 2ft down and had half a wheelbarrow load of dirt around the hole. The ground got damned hard and I was sweating profusely and puffing like a busted train....I remembered my backup Tesoro ElDorado and pry-bar in the 4x4 and walked the 15 minutes back to retrieve them so I could properly use 'REAL' discrim to determine if it was still worth digging any further. I was very happy to hear the signal still zapping away after dialing in the max iron setting on the Tesoro. With the aid of the pry bar, I got 2.5 ft down and hit a soft patch of dirt, right in the middle of my hole...my heart sank, it was disturbed soil. A further inch or two and out popped a huge copper spoon. I'm sure the nearest seismometer would've registered at least 3 or 4 on the Richter scale after my tirade of abuse at the gold gods. After back-filling the hole, I drove home.....

Just because you've got iron discrimination of ANY sort, doesn't mean ALL your big, deep signals are gonna be gold.......

[jasong]

A basic mono coil itself can be turned into a magnetometer already without adding an actual "magnetometer" (fluxgate, PPM, etc), technically speaking. Any iron inside or near the loop is going to change it's inductance, this is a quantity that can be measured, the change in both field strength and direction can be determined, and that's what a magnetometer does. Further, a coil like a DD could be even more useful than a mono loop, by turning it into something like magnetic gradiometer, which might provide enough resolution/information to be useful. I've posted about this gradiometer idea in the past. 

If anything, a magnetic gradiometer would be the more useful tool at the iron nail/metal detector scale, not a simple magnetometer. Even those though, I believe, are not high enough resolution to really be of use on a metal detector in the way people want them to be when thinking in terms of traditional discrim. 

One problem as you swing over variable ground is that it doesn't do you any good if you have no way to tell the difference between slight ground variations in magnetism (pockets of magnetite, hotrocks, variable soils, etc), or a small ferrous target like a nail buried deep. The deeper the iron, the less accurate the magnetometer will be because the more it will sound just like faint, variable soil (vs a massive local field variation near surface). Your discriminator would need a discriminator itself, because to magnetometers, anything ferrous is going to alter the magnetic field present wether it's magnetite soils, a nail, etc. I'm not a detector engineer, but if I were looking at incorporating discrim with magnetometers, that would be the first problem I would see in terms of usefulness and accuracy, and probably why we don't have magnetometers in detectors already since it's not really something hard to build. 

Magnetometers and gradiometers are great for larger targets though. Especially for exploration and larger scale prospecting work. 

[RONS DETECTORS MINELAB]

On 3/14/2023 at 7:41 AM, Steve Herschbach said:

Even with the SDC, 6000 and 7000 I cherry pick targets based on tone, so I am using discrimination - my ear and brain.

I'm hoping the engineers can someday add a visual target ID for tone changes on PI and ZVT for better refining of what I'm hearing.

[phrunt]

It's part of the job of these engineers, working out how to do things that currently can't be done, so I guess all we can do is wait and see where development takes us although I think major investment in gold detectors may start to dwindle with sales slowing and models not meeting sales expectations along with the demise of the African gold rush and ceasing sales to Russia which was a pretty big gold detector market, add to that competition entering the market taking away some of the sales and it's not looking promising.

Manufacturers follow the money, if the money is all in the coin and jewellery detector market that's where the focus will be, I think the Equinox took Minelab by surprise and demonstrated to them a market they can make big money, and they certainly did that, so now if you look at their detector lineup it's rather dominated by treasure detectors and that's where most the new activity has been.

 

 

[afreakofnature]

It’s interesting if that is how they “rank” their detectors.  Which kind of seems accurate to the passerby.