Minelab H1-24 Results

[phrunt]

The control box intentionally picking up EMI to be used as an indication of coil EMI sounds plausible, as the control box isn't going to be picking up the in-ground targets so some sort of antenna with a role of picking up EMI signals and using that to help cancel them out.

[jasong]

There are a ton of different ways that could be implemented now that we have the processing power to do them. A lot of this stuff was techniques that were well known in the 90's because it's what we had to do to adapt lab equipment and tools to specific uses in school. 

A bunch of ideas probably wouldn't work. I probably misunderstand others. That's science and engineering - experiment and try. But I've seen enough in other products and instruments to be pretty comfortable saying that I really don't think detectors are seriously using the power we have available cheaply today.

But again, this is stuff I see greatly benefiting exploration prospecting. Stuff that speeds up ground coverage, saves time. Not as beneficial for flogging old patches type detecting where one is already going slow, and a slow/noisy rig doesn't matter as much.  

In terms of raw power for getting every last deeper crumb out of an old patch, it's going to be hard to be beat an old GPZ with a larger CC X Coil, I agree there. These changes will be smaller advantages for that type of work. That rig is also a poor exploration machine though. 

[Dug D]

I think a big step forward would be a detector circuit that only detects aluminum and indicated that on the screen, sort of like how detectors treat iron/red numbers. Imagine if the Manticore had a range where aluminum appeared like the iron does top and bottom of the screen or yellow numbers. 

[Digalicious]

 

4 minutes ago, jasong said:

The difference between the signal from the ground to the coil is much higher than the difference between taking that same reading somewhere else, say the control box.

Now the same analysis can be applied to EMI. Since it originates from the sun, lightning, planes, cell towers, etc the difference in magnitude is far less as it's picked up between those same two points. So you can more easily determine those types of signals are likely to be EMI. Now - with enough CPU speed you can do further analysis on the signals to differentiate them, and still have results in "real time" before the brain hears anything like Fourier analysis on top of the gradiometry.

This is a massive oversimplification but I'm trying to keep it understandable for all.

Well Jason, I'm glad you're trying to make it understandable for all, but I still don't understand what you're trying to say 🙂

For example, what does the control box have to do with EMI, given that the control box components can be easily, and effectively shielded?

In addition, EMI is hitting the coil at random intervals, frequencies, and harmonics, so I don't see how any kind of timing or analysis can differentiate between that, and the random signals from metal in the ground.

Granted, we know that EMI typically produces signals that are weaker than most coin sized objects in the ground, which is why reducing the sensitivity, effectively reduces EMI, along with losing good targets. We also know that most EMI produces TIDs that range from ferrous to just under zinc. Which is why discriminating out everything below zinc, when cherry picking high conductors, gives the illusion that EMI has been mitigated.

I suspect that EMI and its relation to SMF has been a thorn in the side of engineers for a good 20 years, yet EMI is still a major problem. There's just no way to eliminate random EMI signals in SMF, without also eliminating a lot of good signals. In other words, true EMI mitigation, would be akin to "throwing out the baby with the bath water". 20 years of metal detector engineers working on the problem, seem to agree.

[Digalicious]

1 hour ago, Dug D said:

I think a big step forward would be a detector circuit that only detects aluminum and indicated that on the screen, sort of like how detectors treat iron/red numbers. Imagine if the Manticore had a range where aluminum appeared like the iron does top and bottom of the screen or yellow numbers. 

Ya, that's one of the Holy Grails of metal detecting. With a detector like that, one could repeatedly hunt a beach, park, sports field, etc, and walk out with a handful of various gold jewelry. I'd pay an exorbitant amount of money for that detector. One hunter said he would remortgage his house to buy a detector that could distinguish between gold jewelry and aluminum 🙂

Too bad that distinguishing is not possible with an induction balance metal detector.

[VicR]

Maybe the next gold detector from Minelab will not be able detect deeper but will be able to more clearly identify and amplify the faint signals that we miss - refer to a Bruce Candy / Minelab recently approved Australian patent 2023202011.  The abstract of the patent reads -

A method for detecting a target using a metal detector by producing at least two different modulated
audio tones, by modulating a first audio tone with a first stereo audio modulator signal and modulating
a second audio tone with a second stereo audio modulator signal; and applying at least the first audio
tone to a left side of an audio stereo target indicator indicative of the target, and applying at least the
second audio tone to a right side of the audio stereo target indicator; wherein the modulating of the
first audio tone and modulating of the second audio tone, comprises one or more of the following; a
modulation of a volume of a tone, a modulation of a pitch of a tone, a modulation of relative
harmonics ratios of a tone, a modulation of a chord richness of a tone.

I have never thought about this before but i am assuming that the current signals we hear from detectors are in mono - the same sound in left and right of the headphones. Having stereo signals may give the engineers more scope to amplify the signals we want to hear.

[phrunt]

I wonder if he's moved onto helping with the Coin and jewellery detectors more so than the gold detectors, seeing they've already indicated multiple times in various investor documents that's an area they're applying more focus now.

[VicR]

I think they are referring to gold detectors -  quote below from the same patent

 

The fit-for-purpose high-end commercial "gold" metal detector industry has changed very
considerably since its rudimentary introductions in approximately the 1970s, and this progress continues
unabated. The electronics, signal processing, algorithms and accuracy of these high-end products have
become considerably more complex and demanding. As a result, the R&D investment and design skills
are orders of magnitude higher now than they were a few decades ago. It is imperative at this time of
writing, that for a fit-for-purpose high-end commercial gold metal detector to be successful at detecting as
yet unfound gold nuggets in magnetic soils in know goldfields, it must be capable of highly accurate log
uniform and log-linear distributed VRM ground-balancing, to cope with highly magnetic soils, and have
yet further innovative improvements beyond the previous generation of state-of-the-art products.

 

 

[phrunt]

Odd they've got a wording mistake in it, "soils in know goldfields"

It does sound promising something new maybe under development with gold detectors though, unless it's just a protective patient to stifle competition doing something in the future.  Minelab would patent their lunch ladies homemade BBQ sauce recipe if they could.

[VicR]

Yep - if it doesn't show up in auto correction these days errors have a good chance of getting published.