Chase Goldman

2 hours ago, Digalicious said:

Fisher's DSP on the F75 modified the sensitivity (possibly other settings as well) to give the illusion that EMI was being mitigated.

It wasn't an illusion, its just one of several legitimate ways to attack the issue. The F75 was on the ragged edge sensitivity wise, so they dialed it back slightly and used digital signal processing to cancel EMI.  They also made it so you could switch DST on or off if you were concerned about weak signal masking.  As Steve said in the EMI thread I linked above, the additional sensitivity is worthless if all it is doing is amplifying the noise floor.  

Taking the time to read the technical references reveals that the rule or generalization or whatever you want to call is applicable mainly to power line noise sources.   But given the growing proliferation of 5G transmitters and WiFi 6, solid state switching power supplies, and LED lighting, even detectors with higher operating frequencies will be affected more in suburban and even rural areas as time goes on as evidenced by Steve's anecdote about his noisy 19 khz detector. 

17 minutes ago, GB_Amateur said:

I think that last qualification is very important, and it's not just the Culpeper, Virginia hot dirt and Northern California serpentine that distinguish tough ground vs. Florida peninsula beach sand vs. everywhere else.  I don't live in the mountains nor in a metal ore rich area but it absolutely matters when a small coin (95% copper penny, 25% Ni 5-center, silver dime) gets about 5" deep when comparing VDI on the F75 vs. the better multifrequency detectors that you mention.  I'm not talking about changing a few VDI numbers, I'm talking going from non-ferrous to ferrous VDI and tones. or at least a mixture of those two, soon (another inch) to be simply ferrous.

To that point regarding TID, Chuck, you can also see where things take take a step backwards even when we think we are moving forward.  Reference the TID stability issues that have been noted on the Nox 700/900 compared to the Nox 600/800 and even Manticore is wrangling with TID stability to a certain degree.  This probably just illustrates the "no free lunch" adage as Minelab opened up the TID scale to provide better mid-conductivity target ID differentiation, but so far, it has come with a cost - less TID stability overall.

Without getting into a prolonged back and forth as to whether "...by far, that generalization is empirically and experientially true",  I'll simply link to this excellent thread by Steve that addresses that generalization but also discusses exceptions.  A deeper dive into the thread's technical references and the complex nature of EMI reveals that it's hard to lean too heavily on a single, convenient truism as the variables that affect the outcome of how a detector responds to the vast variety of EMI sources are also numerous. 

Nevertheless, some great nuggets about detector EMI susceptibility and what you can do about beyond sensitivity reductions and frequency shift based noise cancellation routines.

FWIW, I was still curious and asked an expert a general question about metal detector EMI susceptibility and operating frequency and this is what they said about it:

Metal detectors that operate at higher frequencies, typically above 10 kHz, are more susceptible to electromagnetic interference (EMI) than those operating at lower frequencies. This is because higher frequency signals are more prone to interference from other electrical and electronic devices, including power lines, cell phones, radios, and other metal detectors.

At higher frequencies, the metal detector's circuitry and coils are more sensitive to changes in the surrounding electromagnetic field, which can cause false signals and reduce the detector's overall performance. In addition, the higher the operating frequency, the more likely the metal detector is to generate EMI, which can interfere with other electronic devices in the vicinity.

To minimize the effects of electromagnetic interference, metal detector manufacturers often incorporate features such as ground balancing and sensitivity adjustments, as well as shielding to protect the circuitry from outside interference. However, even with these measures, it is still possible for metal detectors operating at higher frequencies to be affected by EMI, particularly in areas with high levels of electromagnetic activity.

That expert...ChatGPT.  🤣

Clears things right up.  SMH

34 minutes ago, Digalicious said:

Hmmm.

I'm not understanding how 4 is better than 5. Not just because it's only a 1 khz change, but also because both those frequencies are very low, and in general, the lower the frequency, the more suspectable it is to EMI.

In my area, anything below around 15 khz is very suspectable to EMI, but still much less suspectable than any SMF mode. 20 khz is significantly better, and 40 khz is more or less dead quite, as it's outside the range of EMI. Well, that's been my experience, and up until this point, the experience of every other hunter that I've discussed it with, or read about.

So ya, Dug's post is a surprise to me. Unless I'm missing something, the only way I could see 4 being better than 5, is if the EMI is being emitted by a single strong source at specifically 5 khz.

 

First of all, one needs to be careful about generalizing EMI and the impacts based on operating frequency.  Different detector operating frequencies have different susceptibilities to different EMI sources like 60 hz power line or florescent light balun noise vs. GHz wireless device noise (cell towers, phones, and wifi) and everything else in between.  So its hard to generalize that high frequencies are generally quieter than lower operating frequencies.  There are scenarios that I have encountered that are just the opposite of that.

Also, EMI can interfere with detector operation from several different avenues and can enter the detector from more than just through the coil acting as an antenna.  Operating frequency selection determines how target signals are filtered as they are processed.  But the control box can pick up sources of EMI independent of the operating frequency selected and changing the operating frequency (the typical noise cancellation algorithms) doesn't necessarily fix those issues. 

Regarding the update, ML apparently did something to address EMI and ground handling with the 4 khz "mode" vs. the 5 khz "mode" and it had little to do with the actual operating frequency other than ML probably surmised that if they could make a lower operating frequency mode less susceptible to EMI then whatever they were doing could be used effectively across the board.  Furthermore, they also needed to be concerned about unforeseen consequences such as reduced depth or target sensitivity, hence they left 5 khz alone in the event their "experiment" had unintended consequences.  True, in general there is nothing that makes 4 khz signficantly less susceptible to EMI than 5 khz, but ML must have incorporated some secret sauce to make the added 4 khz mode to be less susceptible or more stable than the existing 5 khz mode.  That extra 4 khz can also make a significant difference on detection depth for large, high conductive targets.

Minelab introduced 4 khz as a feature "upgrade" a few years after release.  Minelab stated that it was at the request of Asian "horde hunters".  Yes, most were skeptical and scratching their heads regarding the additional frequency given that it was so close to the existing 5 khz setting.  I am pretty sure ML was experimenting with SF noise mitigation, ground handling, and signal processing algorithms as many users noted that 4 khz was incrementally more stable and perhaps had incremental improvements in detection depth on high conductors vs. 5 khz.  In hindsight, it was probably a stealth field test of single frequency enhancements that ML was considering for incorporation into future detectors such as the Manticore, but more likely, this was a test case for enhancements that were eventually incoporated into the X-Terrra Pro.

3 hours ago, The Pest said:

I think that American detector manufacturers should quit outsourcing their production before they try too hard to compete

Garrett does not outsource production.  Don't know about First Texas.

FWIW - Minelab (Australia) outsources production to Malaysia.

1 hour ago, Jeff McClendon said:

If that is polishing the cannonball, okay.

You make valid points about advances in machine versatility and I too would not pull out my MXT or F75 (I still have them collecting dust) instead of my D2, Nox, or Legend, either.  But that cannonball comment was in the context of fundamental detecting technology advancements (the detection technology principle), so yes, I stand by it.  In that context, my view is that we are basically squeezing what little juice is left in the induction balance principle base technology that is the basis for hobby discriminating metal detectors. 

I honestly have not seen anything progress significantly other than bells and whistles and price points after Equinox was introduced 5 years ago.  What Equinox brought to the table was incredible versatility vs. raw capability (a true all terrain, all situation detector that performed just about as well as any other detector out there) at an affordable price point.  It ushered out the era of specialized niche detectors for hot dirt, gold, and salt water.  But there was nothing really new in detecting technology other than a further refined iteration on SMF (been around for decades) and finally taking advantage of processing speed and embedded signal processing and user interface capabilities that have been present in phones and personal computing devices for a decade or more.  Oh and manufacturers seem to be paying more attention to ergonomics.

Since then we have had Garrett attempt an entry level SMF that was barely a blip on the radar screen.  Legend which is just an iteration on Nox with affordability that, yes, makes it more accessible to the casual detectorist, and Deus 2 which is a hybrid of the Nox and Deus 1 that is still outdone by Nox in some respects.  Manticore is also just an incremental evolution of Nox, to be honest.  The advances have been mainly cost, terrain versatility, user interface enhancements, and ergonomics, not necessarily a step change in capability or fundamental technology.  

So with respect to recovering targets with the classics like the MXT and F75, experts with those machines still can hold their own against the Manticores of this world on nominal terrain.  Sure, there is some hot ground and wet salt sand advantages to the latest machines vs. the Fisher and Whites standard bearers but again, that's improved versatility and reducing the need for specialized machines like PI's, Gold Monsters, eTracs, and Excals. 

Yes, we need fewer "specialized" detectors now, and that's a good thing.  But if you are a long-time detectorists with a classic machine primarily looking for spread targets in mild soil which is the norm rather than the exception in the US, the case for upgrading from an MXT or F75 is not necessarily there.  In other words, if Nox or Legend or even Apex did not sway you, what will Garrett do to make a dent now that the market is saturated with 4 generations of Minelab Multi-IQ machines, a dirt cheep selectable frequency machine, the Legend, a forthcoming Quest, and the higher end Deus 2 and Manticores.  In other words, how does Garrett make a splash with the holdouts who have not seen the need to upgrade from an F75, MXT, or AT Max over the past 3 to 5 years?

24 minutes ago, Bootscrape said:

Ain’t that the truth Chase.... it certainly applies to my favourite button, found near a 1840’s era surveyor’s hut for a newly settled town. It is a coat button of the Protector Fire Insurance Co. of London circa 1830. A retired fireman in England is an avid collector of this firefighting memorabilia and offered me a tidy sum for it.

How it got from London to the unsettled Aussie bush would make for a great read.

The new owner has documented his collection in a catalogue. My find is item No.4 in this picture. I feel like I have made a tiny contribution to posterity.

Incredible button.  That is an amazing design and to end up in a catalog.  Fantastic.

3 minutes ago, Digalicious said:

or some sort of true imaging detector. 

An affordable, safe, and compact imaging detector.

1 minute ago, Digalicious said:

...or the seemingly newer trend of not wearing gold or diamonds, but wearing no jewelry, or alternatives / replicas that look just as good, at a fraction of the cost. Then the fact that circulating silver coins haven't been in production for about the last 60 years, get more and more out of detection range, and most people now carry little to no pocket change. 

Yep.  Agreed.  I Mentioned that in my previous post.

5 minutes ago, phrunt said:

Just saying as an outsider looking in, it's different to being an insider looking out.  It's easier to buy a Quest here than a Garrett or First Texas machine, in fact First Texas no longer even has a dealer and the Garrett dealers never had any stock.  I'd find it easier to get a Rutus than an F75.

Agree.  It may really be too late for the US manufacturers to get back in the game.  There are also niche players in the US with interesting and different approaches to detector design such as Tarsacci.  But they are small and niche so difficult to gain any significant market share or make a splash except for a few dedicated fans.

34 minutes ago, phrunt said:

It really does demonstrate how far behind US manufacturers are though when a detector this good is not even on many peoples radar in the US.

Not sure what one has to do with the other.  It just shows that Rutus doesn’t have a strong marketing presence with detectorists in the US vs. XP, Minelab, Nokta, and Quest despite having a great design.  All of these non-US manufacturers have products that far exceed anything the US has to offer at this point.  I don’t think the US manufactures are oblivious to products like the Atrex, just as they know they are getting their clock cleaned by the other better known Non-US players.

Also, as seen in this thread, a not-insignificant contingent of folks in the US are willing to continue to cling to their Classic MXTs, AT Pros, and F75s at this point, despite the demonstrated performance and features gains of these foreign detectors.  Not sure what to do with that but I think it has something to do with the fact that they still work and find plenty of targets and the users are intimately familiar with their quirks and secrets (knowing your detector well generally trumps superior tech in the hands of a newbie).  And like I said previously, these “significant” advances in detector tech, in reality, are only incremental and really only marginally increase finds in the grand scheme of things.  The key being not technology so much as finding and gaining access to the shrinking number of sites that produce finds.

1 hour ago, bigtim1973 said:

Garrett does have a job opening for an engineer position.

They need to drag someone from Europe or Turkey over and make things happen for them again. 

 

Plenty of engineering talent right here in the USA.  Problem is so many other industries are sucking up engineers from the shrinking talent pool (yes there are fewer people entering into college engineering programs every year) and there is no way someone like Garrett can compete compensation-wise for that talent since we are talking basically about designing toys (that’s right people, toys) vs. multibillion dollar behemoths like Google, Amazon, Meta, Tesla, etc. that are working on deploying the real Skynet from the Terminator series. Foreign talent is not necessarily better and frankly someone is not going to come over here just to work for Garrett when they can work for someone else I just mentioned.

Someone earlier talked about eventually hitting a technology wall.  Guess what, we basically hit that wall years ago.  Induction Balance technology is effective but an ancient and crude way to ascertain the nature of a buried piece of metal and now we are just squeezing drops of performance out of it by upping processing speed (where do you go once you can process a signal as fast as a human can swing a coil) and doing some real backflips with signal processing technology and simultaneous frequencies.  But we’re just polishing a cannonball at this point, not really innovating.  Furthermore, the noise floor continues to rise with the proliferation of wireless communication and control technology that it is becoming harder for designers to cut through the EMI similar to how light polllution and SpaceX  satellite constellations are ruining visual astronomy.

As Steve says, now that Axiom is out there and appears to be successful, Garret (the only viable US detecting manufacturer with an active R&D presence) needs to pivot back and build off APEX which was a low risk way for Garrett to dip their toe into SMF (set expectations low by introducing it as part of your entry level ACE lineup) and refresh their mid and flagship level offerings.  

Also, where is the hobby headed?  Relics and gold are not replenished and coinage and jewelry  are disappearing as we are now content to buy stuff with our phones and wear non-metallic silicone SafeRingz instead of gold wedding bands.

Anyway, it’s pretty obvious why the US is lagging in VLF detector innovation.  So the question is whether it’s too late for Garrett to get back into the game.  FT is content to continue serving up warmed over pink and purple variants of detectors they designed more than 10 to 15 years earlier.

I’m a firm believer that location vice detector technology is key to growing the hobby or facilitating individual success.  Harnessing technology and AI to facilitate site research and access as well as for assuring swing coverage my do more to reinvigorate the hobby than incremental improvements in induction balance detector technology (though introducing machine learning into the detector technology mix might be the next game changer).

My nonsensical ramblings, FWIW.

The Garrett Pro Pointer AT (aka the “Carrot”) is a fine water-resistant, general purpose PP and a popular choice.

7 hours ago, midalake said:

The D2 is a good tonal machine until you have fringe targets that do not lock. I have had iron grunts with deep nonferrous and no iron grunts with deep ferrous. What really is disappointing deep nonferrous gives zero hints it might be nonferrous. ALWAYS choppy, ratty,bitey broken signals [just like deep ferrous] My only hope is that I can get the D2 to throw a number. 

I'm with you Dave.  We hunt in vastly different environments so we are going to have different perspectives on D2 machine behavior.  So I don't dispute yor observations on fringe targets in saturated salt sand with black sand mineralization.  I have similar concerns in heavy soil mineralization but overall ID depth suffers to the point that nuances in mode IDs are a moot point - I usually go with a PI at that point.  In mild soil, and full tones, in my experience, a high conductor tone can ring through even if visual TID is getting depressed from co-located iron.   I really just wanted to point out regarding your comment that the video showed poor D2 tonal performance because the on-camera operator was struggling because of dependence on iffy visual TID to attempt to discern the nature (conductivity) of two different non-ferrous targets at depth - which is purely a drawback to using PITCH which has no tone ID capability other than ferrous vs. non-ferrous.  Again, not disputing whether D2 reliably indicates ferrous vs. non-ferrous tones at fringe depths in deep wet salt sand.  You have vastly more experiencece than me in that situation.

2 hours ago, GB_Amateur said:

You can keep the door open without arguing with every person who tries to close it.  Eventually the evidence will clarify and one needs to be ready for that.  In the meantime while you're still holding that door open, even if just by a crack, put yourself in the other person's shoes and respect their views, usually simply keeping your mouth (and fingers) quiet.  It's OK to disagree in silence.

This is sound advice for all who participate in asking for and dispensing advice, Chuck, regardless of where you stand on the present subject at hand.  Thanks for articulating it so well.  I often have to step back and look in the mirror and regain that sense of self-awareness as to whether I'm preaching or just trying to win an unwinnable debate solely for the sake of winning or being proven right, even if it’s only in my own mind.

Sirius - just one last follow up.  As I read through your replies, especially the last one, it is not clear to me whether you still think the quarter is silver or even valuable or just a unique strike on the wrong metal or a no-value counterfeit.  You were willing to scratch up the edge after visiting the coin dealer, after all. 

So your unwillingness to destructively test the coin further might just be that it is not worth the trouble to confirm whether or not the core is actually copper at this point (though you apparently do think there is no copper there) and not because you think it has collectable value.  I get that.  But at this point, i think that is the only way to be sure.  However, if you still want it to be accepted by the CoinStar machine, definitely let it be.  

35 minutes ago, Gold Seeker said:

but if t floats your boat then it's whatever you think it is.

Reminds me of when I was first getting into relic detecting.  I recovered a highly corroded ferrous target at a farm site.  It was a hook or something.  It was non-descript in terms of being able to tell whether it was CW period iron or modern farm junk.  I asked my detecting buddy if he thought it was a CW period relic. Knowing that 1) it had no distinguishing features that could conclusively date the item and 2) it had basically no collectable value either way - he replied, "It is if you want it to be."  Never forgot that and it injected some reality into my idealistic sense of what relic and treasure detecting is all about and the very small potential that any given unidentifiable target I pull out of the ground is some unique relic treasure. FWIW.

Well ok then.  Suit yourself.

Strange you sought and then decided to basically brush off the input of a coin dealer as well as multiple experienced forum members who took the time to respond regarding the potential nature of your find.  But that is certainly your prerogative.  It is your find, after all.

If you feel so inclined, look up Occam's Razor. 

The simple version of that is summed up in the saying:

If it looks like a duck and quacks like a duck, it's probably a duck.

Who knows, maybe there is a small possibility we're all wrong and you have something unusual there.  But if you are basing it on the few hundred clad quarters you've personally seen in various corroded states since you took up detecting a few months ago, then that is a pretty weak position to consider conclusive considering all the variables and the probable millions of clad quarters that are out there exposed to the elements.  If you've seen the pics of Beach Find clad here, there are no "usual suspects" regarding corrosion states and appearances regarding green copper and copper leaching.  It's all over the map.

If you just want affirmation of an "out there" hypothesis, versus usable input, that's fine, I guess.  But forum members like to share honest advice from their experiences not just tell you what you want to hear.  It's also reassuring to get confirmation your feedback is given serious consideration.  I can't speak for the others who chimed in here, but from my perspective, at least, it was just a tad frustrating reading the same counter argument multiple times.  🤔 

Something to think about if you plan to use the forum to get input on your next inquiry. 

Oh, BTW, nice pocket watch you have there that made several guest appearances throughout thread.

Cheers...and happy hunting.

3 hours ago, Sirius said:

I was responding to GB. Basically why would I need to scratch deeply when the core is so close to the surface. I  took a not so tarnished clad quarter and scratched the rim on a brick and it instantly exposed the copper core, whereas the coin I found yesterday didn't show any signs of having a copper core after scratching the rim on a test surface. 
My question now is: could this be a counterfeit quarter?

It really makes no financial sense to go through the effort to counterfeit a clad quarter.  

What it looks like to me is that the copper core of your quarter has circumferentially receded from the edge of the coin whose diameter is now defined soly by the Cupronickel surface clad layers.  This can be explained by the fact that the pure copper is more susceptible to saltwater induced corrosion than the Cu/Ni clad layers, so there is more pure Cu metal lost.  The net effect of that is that when you scratch the edge you are deforming the silver-toned Cu/Ni metal into the circumfrential void created from the receding copper core.  If you instead took a file and scratched off some of the clad surface layer off the face of the coin, you might then better expose the copper core layer than scratching the edge.

31 minutes ago, Sirius said:

I just scratched it to do an acid test on the rim. But my question is why would it be such a thin layer of copper. These things were made with 75% copper 25% nickel clad in mind, as shown with the other coin of the same year. It's curious so i'm still asking around about what it could be.

Not sure what you are asking here (“thin layer of copper”).  The two outer clad layers are 75/25 Cu/Ni alloy which has a silver/nickel appearance. There is no thin layer of copper.  The core is pure copper.  

1 hour ago, Jeff McClendon said:

They had very sketchy target IDs but both had dig me audio

I think we are basically in agreement but it takes a super-trained ear (explained below) to be able to discern anything more from the pitch audio alone coupled with the sketchy TID was that you had a probable symmetric, non-ferrous target as there is no obvious tone ID component in PITCH to let you know if it was a low mid or high conductive target like you have in Mukti tones or full tones.  That was my point in response to Dave’s assertion that the video demonstrated D2 had poor tonal ID charisticstics.  Agree that if you were digging all non-ferrous it was a dig me audio signal but without reliable visual TID, you would have difficulty differentiating a zincoln from a tab from a heavy gold ring in PITCH, though with experience, you can discern more dense/massive targets such as solid gold, silver or copper/clad or an aluminum can bottom as they will tend to give a slightly fuller, more rich sounding audio in pitch.