Interesting (or Just Plain Crazy?) Approach To Ferrous Limits Settings

[Geordiedan]

Watched this video from a UK (Scotland) Minelab dealer/user who has an unusual approach to setting Ferrous Limits for his new Manticore

When I hunt I never use iron discrimination (all metal mode ON all the time) but I do run various degrees of iron bias.  On the 'Nox I tended to use FE set on either 0 or 1 depending on the fields, and with the MC I've just been trying it out at default settings but looking to lower them a little to get back towards my old 'Nox settings.  

NASA Tom has mentioned that:

"Manticore Ferrous Limits Upper = 8 & Lower = 3......is...... EQX F2: '0' equivalent. On paper......the numbers are slightly different; yet, in the real-World Upper 8 & Lower 3....... produces nearly identical real dirt performance resultant. "

So I'd had in mind to work towards something a little like that 🙂

Enter the youtube video - This guy Toddy has advocated running with the upper ferrous limits at about 3, and the lower at zero, i.e. completely wide open screen.  Now that had never even crossed my mind as the purpose of ferrous limits is to make the tone of the target with ferrous characteristics sound like iron.  So running like this anything at all in the lower FE sector is going to chime up based on its conductivity on the x-axis only.  Am I missing something or are there additional benefits to doing this that I'm overlooking?  

By running in all-metal with some lower limits configured I'll still be hearing that there are targets there, just with the iron buzz when they're showing as being ferrous.  I'm not sure I get the idea behind having those all sound like good tones.

Video in question: 

https://youtu.be/RlBvfcTeOkk

[JCR]

His sites may not have any flat ferrous junk & small iron may not be bad about falsing so he can get away with it perhaps?

[GB_Amateur]

That's a pretty thick accent to my ears, but combining Closed Captioning and my own interpretation I think I got the gist of it (didn't listen to the last 4 minutes, though).  Some takeaways (which are neither profound nor new):

1) knowledge of the FBS detectors is going to give Manticore users a head start;

2) as JCR mentions, his goal targets (small hammered coins) and his background trash (no bottlecaps and not a lot of sheet metal bits?) allow him to eliminate the lower part of the Manticore's ferrous settings while still limiting the amount of trash dug.  He seems to hint that he still digs some trash -- I see that as a good thing.

3) given that he notches out the lowest conductive channel (1) to silence coke, I conclude that his ground conditions aren't the friendly beach sand we see on many videos.  I don't know whether his coke distribution is more like hot rocks or spread out ground mineralization noise, but either way he's dealing with something undesirable.

[Chesroy]

I would forget his settings for awhile and get used to the factory settings and what they are capable of, it's going to perform better than the equinox 800 I would suggest so you won't be missing anything. Plenty of time to experiment later. 

[Fell Wanderer]

18 hours ago, Geordiedan said:

By running in all-metal with some lower limits configured I'll still be hearing that there are targets there, just with the iron buzz when they're showing as being ferrous.  I'm not sure I get the idea behind having those all sound like good tones.

This is speculation on my part because I don't have the machine yet. I think the reasoning behind Toddy running the lower ferrous limit wide open, is to increase the separation and un-masking of small cut hammered coins close to iron which are dragged down into the ferrous zone and therefore missed if lower limit was set high. Ferrous and non ferrous targets will sound good outside the grey ferrous zone and will be hard detecting on trashy ground. Nuances in audio response and the indication on screen of a tight dot for a hammered, rather than larger smudge or smearing for trash, may help to distinquish between good and bad targets.

[Geordiedan]

Thanks guys,  coincidentally (?) there's some relevant discussion over on NASA-Tom's forum along similar lines with member steveg - is he on here? (Edit- yes he is, paging @steveg )

I can't sign up to that board due to the security etc being broken so I just have to watch from the sidelines 😞

 

When asked about running a wide-open screen Tom came back with:

"I always start to hunt a new site with FL Upper = 6 & FL Lower = 3. (((And...... I usually end up STAYING on these aggressive settings........unless there is a unusual extenuating circumstance.....forcing me to make SLIGHT tweaks))). These are highly aggressive settings; yet, with a little experience.....your skillset will rapidly improve. These settings on a EQX would equivalate to a F2 = -1. 
"Why" do I use these settings? Because the unmasking (in iron) abilities are tremendous. "

 

Which makes sense in the context of what I was asking above - I'm planning on setting one of the Custom FL profiles up at 6/3 and seeing how it runs on some of my familiar fields 👍

[steveg]

On 1/11/2023 at 9:08 AM, Geordiedan said:

Enter the youtube video - This guy Toddy has advocated running with the upper ferrous limits at about 3, and the lower at zero, i.e. completely wide open screen.  Now that had never even crossed my mind as the purpose of ferrous limits is to make the tone of the target with ferrous characteristics sound like iron.  So running like this anything at all in the lower FE sector is going to chime up based on its conductivity on the x-axis only.  Am I missing something or are there additional benefits to doing this that I'm overlooking?  

 

Geordiedan, 

Yep, I'm here, LOL!

What you said above, in the part of your post that I quoted, is a correct understanding on your part.  As I strongly suspected, and then was able to confirm, is this -- if the Manticore were run with a "fully open" screen (no discrimination, and Ferrous Limits set to ZERO) this would have the same effect as running a Minelab Explorer/E-Trac/CTX 3030 with a "fully open" screen.  Which means, as you were corrrectly alluding to in your post, ALL targets, ferrous OR non-ferrous, would report audibly to the user as a "non-ferrous" target -- i.e. a "good target."  

For those who may be a bit confused by this, I'll explain, but I warn you that it will be long-winded, LOL!

The REASON that with a fully "open" screen, all targets will report a non-ferrous audio tone, is that IN THE BACKGROUND, the Manticore is essentially calculating a ferrous ID, and a conductive ID, for each target, analogous to what FBS machines do.  It's a bit more confusing, on the Manticore, because for some reason, Minelab does not allow us to SEE the FE-CO values directly (for a reason I will never understand).  BUT -- with that said, the FE and CO IDs ARE being "calculated" in the background, for each detected target.  Point being, each target DOES have a FERROUS ID, and a CONDUCTIVE ID, on the Manticore, and this is in my mind a key to understanding how the Manticore works.  The other key to understand is that the AUDIO reported to the user, for detected targets is based off of the CONDUCTIVE ID -- UNLESS the target in question is discriminated, OR falls within the portion of your screen "grayed out" by your Ferrous Limits setting.  (This is quite similar to FBS machine operation, when you have the machine set up with the sound profile of "conductive tones.")

So, to elaborate on the implications of what I've said above...because EACH target detected by the Manticore is broken into its ferrous component AND its conductive component, then with a fully open screen (no discrimination, and limits set to zero), what would be reported in the audio is the conductive component of the target -- i.e. a non-ferrous tone (implying the target is a "good target").  So -- to repeat...if running NO Ferrous Limits, and NO discrimination on the Manticore, ALL TARGETS will report as "non-ferrous."  This is important to understand...and wrap your head around, so as to fully grasp the logic, because understanding this logic fully will directly impact how you may wish to set the "Ferrous Limits" on your Manticore, in various scenarios.

Continuing along this line of reasoning, the ONLY way the Manticore knows NOT to report an iron target as a non-ferrous object (again, due to the audio being based off of the CONDUCTIVE portion of the target) is by adjusting ferrous limits.  When your ferrous limits are set appropriately, then an iron object -- which would otherwise report as a non-ferrous object if the screen were entirely "open," will NOW report as an "iron grunt" (assuming the ID of the iron target falls within the part of the screen that is "grayed out" by your ferrous limits setting).  

So, if this all makes sense, then the takeaway is that we have complete control, on the Manticore, as to where we place that "razor's edge" of a target reporting with either an IRON tone, or a NON-FERROUS TONE.  And therefore, "limits" settings may be more important than some folks realize.  Obviously the more we reduce Ferrous Limits (i.e. less screen grayed out), the more types of targets (iron OR non-ferrous) we will be "forcing" to report as a "good target" with a non-ferrous tone...but with the BENEFIT, potentially, of improved ability to unmask non-ferrous targets hiding in thick iron.  On the other hand, INCREASING Ferrous Limits (i.e. more screen "grayed out") means that more targets will report audibly as iron, allowing us to tend to dig less "junk," BUT, with the caveat that some potentially GOOD targets (i.e. mixed nail/coin scenarios, for one) may then fall within the grayed-out screen (i.e. within your "Ferrous Limits") and thus report with iron audio, causing you to pass over the target without investigating it further. 

BOTTOM LINE -- understanding that all targets detected by the Manticore will have an FE ID and a CO ID assigned, and that ALL targets detected will report a non-ferrous tone to our ears, UNTIL we set our Ferrous Limits "appropriately," is what must be grasped to properly utilize the Manticore to its fullest.  Until this is understood entirely, then it seems likely that the best way to approach things is to do what Chesroy said, above, which is to run factory default Ferrous Limits, until we understand the machine better, and then begin customizing (which will likely be site-dependent/trash dependent).

Hopefully, this makes sense, as it can be confusing until you wrap your head around it (and this is why it's easier for folks familiar with Minelab FBS machines to understand the Manticore perhaps a bit more quickly, i.e. a "head start" on figuring the machine out, as GB_Amateur noted above...)

FINALLY -- to bring this around to your original question, Geordiedan, what that particular user (Toddy) is doing in the video (though I haven't watched the video) is choosing to allow a vast majority of the objects detected -- including a good many of the iron targets -- report as a non-ferrous target.  This will, of course, cause him to hear (and potentially dig) alot more "good-sounding" targets that are actually iron (again, due to the minimal Ferrous Limits settings), but on the other hand, will help him reduce the number of times the machine improperly assigns an iron tone to a potentially good target...

Tradeoffs.

Steve

[GB_Amateur]

17 minutes ago, steveg said:

So, to elaborate on the implications of what I've said above...because EACH target detected by the Manticore is broken into its ferrous component AND its conductive component, then with a fully open screen (no discrimination, and limits set to zero), what would be reported in the audio is the conductive component of the target.

Good to know, and it answers a question that bugged me forever (well, for almost 5 years owning the Equinox) -- when Equinox Iron Bias was set to zero (FE originally and F2 eventually), was there still iron biasing occurring?  Given what Tom D. has said about the correlation between the FE/F2 Equinox settings and Ferrous Limits settings, and throwing in what you've just said above, the answer appears to be a big fat YES!

OK, regarding what you call 'reporting' and I call 'sounding off', I'm looking for more clarification.  For simplicity sake (and for some of us, the way we always hunt), let's assume there is no notching in place -- none, zero, nada.  (Notching shows up as complete vertical bars/rectangles going from the bottom to the top of the 2-d screen on the Manticore.)  You point out that with no regions grayed out by Ferrous Limits, everything that sounds off will give a sound corresponding to the (conductive) tone settings.  If we add Ferrous Limits (from the top or from the bottom, or both) and a target lands completely in a gray zone, it will give an iron tone (grunt) only?  If it falls completely in the clear part (not grayed out) it will give a tone determined by the conductive tone settings.  And if the target falls partly in the gray and partly in the clear, it will give some combination of iron grunts and conductive tones (just like the Equinox often does)?

As a side note, I'm rereading (at bedtime, about 2 pages per day) the following treatise.  For those wanting a clarification "from the horse's mouth" (Bruce Candy) on this FE vs. CO stuff, you might want to follow my lead:

 

[Geordiedan]

Great reply, thanks @steveg 

That affirms what I thought to be the case, and while I guess Toddy in that video may have his reasons for wanting literally everything to sound conductive, I think I'll run with something more like NASA Tom's suggested settings this weekend.

On the plus side, this was one of the key reasons I was interested in the Manticore.  With the 'Nox, setting Iron Bias to various degrees all I knew was that "some stuff" was being notched up as being more likely to be iron with each setting.  I ran f2 for a while but never really gelled with it (I've never dug a bottle cap in my life) so ended up back with regular Fe set at either 0 or 1 depending on the area.

With the Ferrous Limits and a suitable amount of trial and error (or, in time, cribbing the settings of the professionals once these have been out for a while in your native country 😄 ) then it should hopefully be possible to come up with some amazingly specific settings to isolate your preferred targets from the surrounding trash.

(Edit to add - I'll also be following the main Manticore thread over on Tom's board to see what he has to say on your tones query 🙂 ) 

Thanks again to all for your thoughts, it all helps me with my learning curve 👍

Dan

[steveg]

3 minutes ago, GB_Amateur said:

Good to know, and it answers a question that bugged me forever (well, for almost 5 years owning the Equinox) -- when Equinox Iron Bias was set to zero (FE originally and F2 eventually), was there still iron biasing occurring?  Given what Tom D. has said about the correlation between the FE/F2 Equinox settings and Ferrous Limits settings, and throwing in what you've just said above, the answer appears to be a big fat YES!

OK, regarding what you call 'reporting' and I call 'sounding off', I'm looking for more clarification.  For simplicity sake (and for some of us, the way we always hunt), let's assume there is no notching in place -- none, zero, nada.  (Notching shows up as complete vertical bars/rectangles going from the bottom to the top of the 2-d screen on the Manticore.)  You point out that with no regions grayed out by Ferrous Limits, everything that sounds off will give a sound corresponding to the (conductive) tone settings.  If we add Ferrous Limits (from the top or from the bottom, or both) and a target lands completely in a gray zone, it will give an iron tone (grunt) only?  If it falls completely in the clear part (not grayed out) it will give a tone determined by the conductive tone settings.  And if the target falls partly in the gray and partly in the clear, it will give some combination of iron grunts and conductive tones (just like the Equinox often does)?

As a side note, I'm rereading (at bedtime, about 2 pages per day) the following treatise.  For those wanting a clarification "from the horse's mouth" (Bruce Candy) on this FE vs. CO stuff, you might want to follow my lead:

 

GB_Amateur --

EVERYTHING you said in the middle paragraph of your post (regarding limits, and tones, etc.) is exactly correct.  You understand it correctly, and you explained it quite well.

That paper from Bruce Candy is EXCELLENT.  A very good read.

Finally, to talk for a minute about what you said in your first paragraph...

Essentially, I know what you are trying to ask, and so I will tentatively say "yes."  I say TENTATIVELY, because essentially your "point" is correct, i.e. your logic/reasoning are consistent and reflect that you understand quite well conceptually.  BUT -- I am not sure if understanding the way the Manticore works can be "applied back onto the Equinox" directly.  In other words, I am not sure if the Equinox explicitly "calculates" a FE and a CO value "in the background," like the Manticore does.  BUT -- I am thinking that it does NOT.  IF IT DOES -- then, yes, what you said would be precisely correct.  It would equivalent to saying that even with FE (or F2) set to zero, there was STILL some "iron bias applied," or -- in Manticore terms -- still some "Ferrous Limits" with "grayed out screen" in place, in the background.   Because, of course, running FE or F2 at zero STILL allows some targets to report as iron.  We can adjust for "iffy" or "mixed" targets on the Equinox to make it MORE LIKELY that we hear conductive tones mixed in with the iron tones (minimizing iron bias), or LESS LIKELY that we hear any conductive tones (i.e. mostly iron grunts) on the same target, by maximizing iron bias.  BUT -- even set at ZERO, a nail can still report as a ferrous tone and ID.  So, YES -- it is "as if" there is still some "iron bias" (or, in Manticore terms, "ferrous limits") in place, even though we've set FE/F2 to zero.

We are delving a bit here to the fringes of my understandings of detector operation, BUT with that said, -- I will say that I THINK the Equinox leans just a little bit toward OTHER machines (though with plenty of DNA that it shares in common with the Manticore), with respect to the way it ID's iron, from the perspective that -- again -- I don't THINK the Equinox explicitly calculates both a ferrous and a conductive ID for each target, in the background.  I may be wrong on this, but to me, I think about the way non-Multi-IQ/non-FBS machines will calculate JUST a single ID, and somewhere along the ID scale, the algorithm assigns a "break point" such that below that point, the machine calls the target "iron," and above that point, the machine calls the target "non-ferrous."  And the way I think of "iron bias," (but which I know is not TECHNICALLY correct, it's just how I picture it in my mind), is that what you are doing by adjusting iron bias on the EQX, is adjusting slightly that "break point" the machine uses to call a target iron, vs. non-ferrous. 

This, again, is not technically correct, as I am essentially certain that what is in fact happening inside the guts of the EQX is that the multi-frequency approach is being used to get different "reads" of the target, in other words, sort of a somewhat "less explicit" FE and CO reading of the target as compared to what occurs in the Manticore or FBS where EXPLICIT FE and CO are calculated.  And it is in this "less explicit" evaluation of FE and CO on the EQX that is where "iron bias" enters the picture.  So, said a different way, I think EQX "kind of" reads FE and CO characteristics of each target, and we can "bias" the EQX's readings of these properties via the iron bias adjustment, BUT, that Manticore accomplishes a "more refined" or "more precise" examination of FE and CO properties of targets, assigning EXPLICIT values to both FE and CO.  And that "more refined" examination of FE and CO then allows such things as the 2D screen, and the more "precise" adjustments that occur with "Ferrous Limits," as compared to iron bias.

I hope this makes SOME degree of sense, what I'm trying to say, and is at least SOMEWHAT understandable.  

BUT -- I'll note that it is possible that what you assumed is actually quite correct, i.e. that EQX IS more "explicitly" calculating FE and CO in the background, and thus that iron bias is very much the same as "Ferrous Limits" on the Manticore, with the difference simply being that we just can't FULLY adjust iron bias to the degree that we can force ALL targets to ID as "purely non-ferrous" (as can be done on the Manticore).

Steve