Visual Sound Analysis

[Chase Goldman]

22 minutes ago, Digalicious said:

If an aluminum target is hit at 1 Khz and then 100 Khz, would the target signature change? If a gold target is hit at 1 Khz and then 100 Khz, would the target signature change?

What I'm getting at with the above, is if there is an amount of change in the signatures between the two, or one signature changes and the other doesn't, then can that amount of change (or lack thereof) be used to help differentiate between gold and silver?

 

The short answer is yes.  That's why ground compensation and ferrous discrimination/ferrous bias are more effective with multifrequency detectors.  Without multifrequency there is no iron bias and high mineralization ground is harder to tame.  I think the issue is that it's a lot easier to identify the frequency-based signal processing deltas for ferro-magnetic targets than it is for purely ferrous targets and the signal processing has to really work hard to identify those small signature changes AND differentiate them from noise.  Again, this is where applying machine learning might provide a leap.

[Steve Herschbach]

15 hours ago, kac said:

The likely hood of a particular flip tab in an area having exactly the same response and id's as a ring is pretty remote.

I find it odd someone would keep digging the exact target type over and over again but in kindergarten we had craft time where we would doodle out something in crayon and use paste to make something of it and there was always one of those kids in the back eating the supplies.

Because the odds might be low, they are not zero. So you guys hit a place repeatedly, notching out your low odds targets. Eventually the target id numbers you are digging will find nothing. It’s not a matter of if, but when. At that point you either abandon the location, or go dig the numbers you passed up before. If you don’t, somebody else will. As good finds deplete people drift more and more to digging everything, because eliminating any trash item also can eliminate good items. Thats why looking for reasons not to dig is in the long run a fruitless endeavor. It only works when cherry picking works, and eventually cherry picking will play out at any location. Nugget hunters figured this out a long time ago.

[Digalicious]

6 minutes ago, Chase Goldman said:

The short answer is yes.  That's why ground compensation and ferrous discrimination/ferrous bias are more effective with multifrequency detectors.

Right, but if I read what you said correctly, then that isn't what I was getting at Chase 🙂

I'm heading out for a few fours, but later tonight I'll explain what I mean in a much more detailed and thorough manner.

[Chase Goldman]

22 minutes ago, Steve Herschbach said:

Because the odds might be low, they are not zero. So you guys hit a place repeatedly, notching out your low odds targets. Eventually the target id numbers you are digging will find nothing. It’s not a matter of if, but when. At that point you either abandon the location, or go dig the numbers you passed up before. If you don’t, somebody else will. As good finds deplete people drift more and more to digging everything, because eliminating any trash item also can eliminate good items. Thats why looking for reasons not to dig is in the long run a fruitless endeavor. It only works when cherry picking works, and eventually cherry picking will play out at any location. Nugget hunters figured this out a long time ago.

Exactly,  in the grand scheme of things, metal detectors are a shortcut to finding treasure you can't see.  The alternative is simply digging holes (based on research or other relevant clues (e.g., surveys or probes) or at random) - which is what miners, prospectors, some relic hunters, and archeologists do.  We keep adding features to detectors add more shortcuts (i.e., cherry picking), but at some point you are just left with the trash and you need to do the hard work (i.e., dig up and recover the "trash" to ID it or get it out of the way) if you want to have the hope of squeezing any more treasure out of the site.

[GB_Amateur]

1 hour ago, Chase Goldman said:

The next enabling technology for advancing the sophistication of both visual and audio target ID representations from where they are today probably resides in the detector designers' effective harnessing of the power of artificial intelligence/machine learning.  Imagine a detector that gets smarter/more effective at target identification (and has the ability to evolve how it presents that more effective data to the detectorist) the more you swing it.  That is probably the next frontier or evolution/revolution in advancing the state of the art in metal detection.

I'm in agreement, at least in a theoretical view.  Training takes quite a bit a lot of input data.  But maybe detectorists could collaborate, uploading results to common database website.

There may also be a downside to this, acceptable by some but maybe not by others.  That is the partial (or more) removal of the skill of the detectorist.  Here's a loose comparison which probably instigates its own debate, but I'll go with it anyway.

How much gold is $1 worth?  I'm not going to look up the spot price but recently I think I've seen USA $2400/ozt so I'll go with that -- at least its ballpark for this argument.  Divide those two numbers and you get 1/2400 of a troy ounce of (pure) gold is worth $1.00.  480 grains (abbreviated 'gr') per ozt, so a grain of gold is worth about $5.00.  1 gr is about 0.065 grams (abbreviate 'g') so 0.013 g of gold is worth $1.  Folding in purity of nuggets, let's say 0.015 g.

Do people get satisfaction from digging an 0.015 g of gold?  Many do; however it's obviously not because of the monetary value but rather the difficulty of doing that, both from a skill standpoint but also in some sense the rarity of even this size nugget's findability.  Compare that to the accomplishment of finding four USA 25 cent pieces (aka 'quarters').  Yes, some see that as an accomplishment and this isn't meant to demean anyone.  But for a lot of people there is a big difference.

OK, now create a tool that is so good that the novice and the seasoned veteran have the same chance of finding a tiny nugget.  (They still have to be placed in the right spot, another skill which isn't equally shared....)  Does that deteriorate the feel of accomplishment for some.  (Yeh, I know, the detector manufacturers don't give a rat's a__ if they lose a hundred experts for every thousand novices they gain.)

[kac]

I don't use notch discrimination but instead use tone breaks on known trash items. This gives me a junk sound on junk and better targets will come through.  High trash areas I use smaller coils.

Much of park hunting especially for fresh drops there is no need to worry about masking but hunting old sites takes a different strategy where surface trash should be picked up like fresh drop cans and can slaw.

Someone doing a dig all approach would be better off in all metal mode or use a PI. Pointless to even use a vdi, tone breaks or anything at that point if your just going to dig it anyways.