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On 10/5/2017 at 8:08 AM, Steve Herschbach said:

Target masking is far more an issue than depth in many locations. Let’s face it, where humans congregate the most, and lose the most stuff, is also where the most trash resides.

The more I learn (by reading and experience) the more I realize that unmasking is the holy grail future of induction balance (IB) detectors.  Dankowski has been emphasizing the issue for years (as your link to a 2000 article shows Dankowski - Beneath The Mask).  The sites I hunt are visciously peppered with iron, small and large.  That goes for old homesites here in the Midwest and out West, at old abondoned mines, placer sites, and ghost towns.  As bad as littering is today, at least we have trash barrels, recycling, refuse collection, and advertising pleas to keep the world a beautiful place.  I get the impression that back in the 19th century the thought didn't even occur to them.

People can still cherry pick (using strict discrimination) to avoid the trash.  If all you're after is recent drops (clad, zinc, and maybe a few pieces of silver jewelry) then go for it.  I want old stuff and, as you note, that means dealing with lots of trash.  But even careful hunting today is hampered severely by masking.  As Tom D.'s report shows, not only don't you hear the good target, sometimes you don't even here the bad ones!  How do you know there might be good target being masked if your detector responds as if there is no metal at all within its search field?!

It's my impression that masking is just as big of a problem for nugget hunters.  Does it just get less attention because most nugget hunting is done with pulse induction (PI) and zero volt transmission (ZVT) technology, which (AFAIK) doesn't offer much discrimination anyway.  If you're really going to dig-it-all, including iron, then eventually you're going to find just about every piece of detectable metal within range.

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Here's a story, that illustrates the masking problem quite well.

Two days ago, I was asked to come try to find a wedding ring that a guy had lost.  It was lost in a small 30'x30' area that, back in the late 90s when he lost it, was a pig pen.  He was slinging food in for his two pigs, and the ring flew off.  He lost it in the mud.  So, armed with my friend's E-Trac (my Explorer is at Minelab for repairs), I set out to search for the ring.  The gentleman who lost the ring was there with me, and I asked him several questions, about size, composition, etc. -- and about exactly how and where he felt he lost it. 

I then began hunting and in and near that 30'x30' area, but after a good hour or so, nothing.  We talked about how the pen was always muddy, and with the pigs walking all around through the mud, their hooves working it pretty deep when it was real wet, we felt like the ring could possibly be as deep as 12" or so.  SO, I hunted more slowly, listening for, and digging more "iffy" targets, including a few bent nails that were real deep, and that I thought had a chance.

After still not finding the ring, I was about to give up.  I was struggling a bit not only because it was a somewhat unfamiliar machine (haven't swung an E-Trac in years), but also because I was unfortunately without my headphones -- and with the wind, I couldn't hear threshold, etc.  Just the tones.  Anyway, I told him that it was my guess that if the ring was within 8" or so of the surface, it should be an easy dig.  So to test that, I dug a round plug, which stayed in tact when I removed it, and dropped my OWN ring into the bottom, and pressed it down to a measured 8".  I then put the plug back in the hole, and swung the machine over it, to see how well the machine would detect it.  But, shockingly, NOTHING.  I couldn't believe it.  SURELY an E-Trac would hit my 8" deep 14K man's wedding band...so I switched out of Auto +3 to manual, maxed out sensitivity.  STILL nothing.  Not even a peep.  I was shocked, and almost embarrassed in front of the guy (who knew nothing about detecting).  So, shaking my head and mumbling about how I "couldn't believe it wouldn't hit an 8-inch ring," and how "that doesn't even seem possible," I dug the plug back out with my hands to retrieve my ring, and...no ring.  So, I grabbed my Pro-pointer and stuck it in the hole, and got a signal on the side of the hole.  Nope.  Nail.  SO, I checked the plug.  Got a signal.  Nope, another nail.  Long story short, I finally found my ring in the loose dirt, just off to the side of the plug, so I filled the hole back in, hunted a bit more with no luck, and gave up and apologized to the gentleman.

Stupid me, it wasn't until the drive home that the lightbulb went off, and then I felt like an idiot...DUH!  The ring was MASKED by the nails -- I just didn't know it while running the coil over it because I couldn't hear the machine's threshold without the headphones (and thus couldn't hear the null I am sure I was getting, passing over those nails while trying to detect my ring)!!  

Moral of the story is, that was just another stark reminder for me of how much masking cripples our ability to find that for which we are searching, and suggestive of just HOW MUCH good stuff is still in the ground, even at "hunted out" places...

Steve

 

 

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On 10/5/2017 at 5:15 PM, steveg said:

 The ring was MASKED by the nails -- I just didn't know it while running the coil over it because I couldn't hear the machine's threshold without the headphones (and thus couldn't hear the null I am sure I was getting, passing over those nails while trying to detect my ring)!!  

Moral of the story is, that was just another stark reminder for me of how much masking cripples our ability to find that for which we are searching, and suggestive of just HOW MUCH good stuff is still in the ground, even at "hunted out" places...

Steve

Wow.  That really drives the point home Steveg. 

So how do we combat that? 

  • Work the locations from multiple angles so the coil can find the edge of a good target masking the nails instead of visa versa?
  • Smaller coils to try and work between the nails/iron
  • Dig the threshold nulls to clean out the area?
  • Machines with faster recovery?

I am curious (as an Explorer and Etrac user - and hunt with an open screen in ferrous with my Explorer and a disc'd screen in conductive with the Etrac) if the Explorer would have had any different results.  And bringing it all back around to the topic subject, how the new E800 will handle this... I guess that is the question we are all waiting to be answered.

Thanks for the post Steve... definitely food for thought as I head out for a lunchtime hunt in a nail infested park :)

Tim.

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Tim,

As far as I can tell, the answers to your questions are yes, yes, yes and yes!

This -- working in iron -- is where I need the most growth, as a detectorist.  I have focused my efforts on "hunting deep," as that is where SOME of the remaining goodies are, in heavily hunted public spots; meanwhile, the REST of the goodies are masked (or partially so).  I am not good at hunting in iron, but I intend to improve, and I'm hoping the Equinox will be a tool with which I can begin that improvement.

According to Tom Dankowski Dankowski - Beneath The Mask, we would be shocked beyond belief if we knew how many targets are undetectable, due to masking (as he demonstrated in that "Behind the Mask" article Steve linked, and which I have read several times).  He states that we cannot do ANYTHING yet, technologically, to allow us to detect truly "masked" targets.  He says we are only barely making inroads (technologically, in terms of detector design) into finding targets that are CLOSE TO iron, through relatively recent advancements such as faster recovery, as well as apparently some different styles of presentation of audio/tones (i.e. revealing in a "more intelligible way" the presence of a good target next to iron).  

Whatever the case, I intend to learn this skill, as best as I possibly can, because I do think this is where a huge number of the targets we seek, that have yet to be found, remain hidden. 

I don't know if the Explorer would have done better; I tend to believe that when working in iron with FBS, you are starting off "handicapped" to begin with -- i.e. not the best tool for the job, as it has been explained to me (though others disagree).  But I can't vouch for that either way, as -- like I said -- I am extremely "green" with respect to working well in iron.

Whatever the case, yes...this was educational for me.  I am well aware, intellectually, the difficulties of detecting in iron, and how targets are easily hidden by the presence of iron.  But this REALLY drove the point home, in case I needed a reminder of just how bad we can be "blinded"...  Those two nails were not huge, maybe 2" long, and rather thin...but they absolutely BLINDED the E-Trac.  NO WAY POSSIBLE, with the E-Trac, do I ever find my ring, if I didn't KNOW it was down there, having just buried it...

Steve

 

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All the suggestions noted for trying to defeat masking help, but the key thing is the detector response time. The BBS/FBS detectors have a very slow response time and no amount of hunting methodology can ultimately defeat this.

All you have to do is spend to time on some basic tests like I did at this thread to show this clearly. It is not that the BBS/FBS detectors are not great units, but this is one area in which they simply do not compare well to other detectors.

The XP DEUS reactivity setting shows this well. Note that there is a direct trade off in response (reactivity) speed and maximum depth. A slow response allows the detector more time to take a "snapshot" of what's under the coil. The detector has more information to work with, and the audio response is full and easy to hear.

Fast response times "clip off" the signal. The faster you do this, the more depth is impacted. The audio response literally gets shorter and at high speeds is so attenuated it can be difficult to pick out a target signal. Think "beeeeeeep" versus "bip". In dense trash however attaining maximum depth is not as important as fast recovery time. The secret is being able to adjust the detector for either wide open spaces or dense trash - or anywhere in between.

xp-deus-reactivity-example.jpgxp-deus-v4-reactivity-chart.jpg

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I agree my pet hate about BBS/FBS is the way they blank when they pass over an Iron target  and they don't switch one until the coil is well past it and then any good targets in close proximity are lost for good, BBS is the worst of the two, because even though the Sovereign GT has an Iron mask switch with on and off positions that Iron mask is still running in the background so you can't disable it even in the off position, And when you sweep over an Iron target it nulls but if there is more than one Iron target in the ground the Threshold may not return until you have made many sweeps of the coil and only seeing side by side testing made me realise just how many Good targets I was missing and both types lack sensitivity of Single frequency machines to tiny Items and nuggets. This was the main reason for me changing brands, But if Minelab would have had a fast machine like this back then I would still be using them.

John. 

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3 hours ago, steveg said:

...Whatever the case, I intend to learn this skill, as best as I possibly can, because I do think this is where a huge number of the targets we seek, that have yet to be found, remain hidden. ...

Steve

 

As do I Steve!  I think all of us turf hunters have come to grips with the fact that the good ol' days of walking through a dated park and getting easy high tones are long past (even though I wasn't detecting then... I still miss it.. haha).  So, as Steve H. has said many times... we just need to be smarter in our approach to detecting, and part of being smarter is using the best tools for the job... I may be dreaming a bit... but maybe the E800 will have me seeking out those iron infested parks that most of the other detectorists in the area avoid like the plague.  I'm willing to work for it... sounds like you are too :).  Tim.

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On ‎10‎/‎5‎/‎2017 at 8:08 AM, Steve Herschbach said:

CTX owners like to kid themselves about how well it does in dense trash because, as they say, they have recovered good targets in dense trash. Well yeah, and left more behind then you found! The CTX is an improvement over previous BBS/FBS models when dealing with dense trash, but the fact is slow recovery and target masking are the CTX Achilles Heel. The Equinox may not “go deeper” than a CTX on a dime per se, but it should easily be able to recover dimes (for example) the CTX misses just based on recovery speed alone. Target masking is far more an issue than depth in many locations. Let’s face it, where humans congregate the most, and lose the most stuff, is also where the most trash resides. If the Equinox pulls good finds out of those locations that the CTX consistently misses due to having a faster recovery speed, what does that say about depth?

Dankowski - Beneath The Mask

 

I just went back and re-read the "beneath the mask" article.  My head is spinning.  Thinking about all the nulls, and silent masking I have walked over, even just today...  I haven't used a "fast" machine like the Deus and now the upcoming E800, but have noticed a difference in the types of targets I have recovered while spending time learning the ATX Pi on turf.  It didn't connect, but thinking back, I found several targets (coins and other relics) in an area I have absolutely pounded with my CTX, Etrac and Explorer... some after removing some ferrous bits... It is starting to connect now.  Thanks Steve.... with every post you are making me a more educated hunter.  Tim.

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This video I made might help if you take the etrac back out to your nail bed?  I use this as my last resort - last pass to squeak out a tiny bit more targets.  But in your case this set up just might hit the ring?

 

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2 hours ago, khouse said:

This video I made might help if you take the etrac back out to your nail bed?  I use this as my last resort - last pass to squeak out a tiny bit more targets.  But in your case this set up just might hit the ring?

 

Thanks for reminding me about this video Khouse... I remember watching it from another forum link and I was amazed by the results then.  

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