2D Display Top and Lower Half Meaning?

[CliveHamy]

Hi Folks

I went and bought the Manticore and the difference in what it is telling me compared to my old Nox 800 is brilliant. Now I'm trying to understand it better. A simple fundamental question I've not seen answered anywhere follows........ 

I tried asking this on a Minelab facebook blog and all I got was patronising comments from non-minelab "top contributors" telling me to "just listen to the tones" or "don't worry about it", "it's not important, I don't need to know"

The question is:- What is being measured & displayed in the lower and upper half's of the 2D display? - OK I've read the manuals and the blogs, I know from experience that ground effect mineralisation, and small iron appears in the upper half, and large ferrous in the lower half, but how and what is actually being displayed?  I get it that conductance is along the middle from left to right, but as a scientist what is above and below the line and why two half's? We are told it is a Ferrous indication, and I assume that it is a measure related to the amount of inherent magnetic response (not sure that is the right word) as that is a unique characteristic of iron compared to non-ferrous.

I find that if I understand how a system works I'm better placed to understand the meaning of the outputs.

With the NOX600/800 the VDI numbers started from -10 to 0 and it was discussed on the Nox that this represented a negative phase difference characteristic of small Iron, and that non-ferrous materials gave a positive phase difference (along with falsing from large corroded iron) Is the 2D display showing negative phase difference above the line, and somehow larger falsing larger Iron below? - Just guessing what is going on here.

Thanks in advance

Cheers Clive

[TampaBayBrad]

5 hours ago, CliveHamy said:

small iron appears in the upper half, and large ferrous in the lower half, but how and what is actually being displayed?  I get it that conductance is along the middle from left to right, but as a scientist what is above and below the line and why two half's?

As a scientist, you are much more inquisitive about the display than us regular detectorists. By that I mean that I am satisfied with the manual explanation that the top half is for displaying small iron objects like screws and nails and that the lower half is displaying larger flat iron objects like steel bottle caps.

So....how it arrives at doing that I have no idea and (not being mean), I don't care. But I do understand that you would like to know how it is arriving at where to plot the target. My guess would be simply how big of a difference/disturbance in the transmitted signal versus the received signal did the iron object cause due to it's relative size. A nail or screw=small disturbance, larger flat item=larger disturbance when the detector compares it's transmitted signal to what it receives back.

But that's just my non-scientific educated guess. So is that a theory or a hypothesis? 😄

[Chase Goldman]

If you want to dip your toes into more of the science, then download and read this Minelab article on how detectors use target reactive and resistive response to the transmitted magnetic fields to characterize targets and how designers leverage simultaneous multifrequency transmitted waveforms (such as those used by the Manticore, Nox, Xterra Elite, and Vanquish as well as the older BBS and FBS detectors) to extract even more information about ground characteristics and ferro-magnetic targets to compensate for ground effects and better characterize ferrous targets.  It is generalized theory and a few years old, but largely based on Minelab detector designs, so you won't get the specifics on why certain targets show up where on the Manticore's 2D display, but it might shed more insight into what the Manticore is doing with that 2D display.  With Minelab not readily providing any more information than they have in the manual and with Minelab's typical secretive wariness about revealing too much of the inner workings of their design to competitors, it's about the best you are going to get as to what is really going on with Manticore.

Another way to look at the 2D is that it is simply a sophisticated visualization of iron bias on your trusty Nox with a more intuitive way to not only set but also interpret the target feedback you are getting vs. just the audio feedback your received from the Nox (with more targets "sounding" like iron the more you increased the iron bias setting (in other words, the detector was more inclined ("biased") to identify iffy targets as iron, depending on how you set your iron bias, resulting in less ferrous falsing (but also the possibility of non-ferrous masking or non-ferrous misidentification as ferrous.

As far as the "X-axis" is concerned on the Manticore 2D display - I am not sure the algorithm's that ML uses to determine whether a target should be displayed above or below the non-ferrous conductivity centerline (in other words, how ML is able to tell the difference between large and small ferrous - for example, it can't just be based on intensity because deeper large targets might have less intensity than extremely shallow small targets, so there is something more sophisticated going on there).  However, the way I interpret the display is that target plots that are further away from the centerline mean the Manticore is "more certain than not" that the target is ferrous and if it is closer to the centerline, then there is probably more "uncertainty" about the nature of that target.

The same goes for plot "smear" which can indicate multiple TIDs being calculated (horizontal smearing from multi metals or target shape irregularity) as well as uncertainty in ferrous response (vertical smearing) or both ("s" shaped smearing). 

So I tend to simply ignore the targets further away and most smeared indications (unless I suspect a coin spill) etc. unless I am specifically targeting ferrous. 

ML has also provided a number of 2D sample plots in the user guide for some specific target types to help you better interpret what you are seeing on the display and correlate that to a real world target type.  Hope that helps.

 

[Skull diver]

12 hours ago, CliveHamy said:

Is the 2D display showing negative phase difference above the line, and somehow larger falsing larger Iron below? - Just guessing what is going on here.

I can't provide a good answer at the level You'd expect, but for sure Your it is the most accurate description yet, right in those words.

While on other machines like Nox or any brand with this system one visualize a negative reading below zero, on the 2D screen there's a new design of an older Fe/Co chart previously seen on Ctx3030.

Once upon a time there was a certain Fe component and Co component giving a more or less precise coordinate and trace on the screen in a squared graph.

In a few words now, anything far from the center line We see in the panel it is rarely worth something unless "the place" needs some investigation.

You'll see with some practice that an elongated trace, vertical or not, even passing through the line and going upwards or downwards, rarely it is a good object or at least in good shape. Rusty?Maybe...Near something rusty, maybe again, but never noble alloy or mixed metals coins giving a clear dot ON the line.

As every other instrument, it can fails, but with honesty, I still don't find the case when a certain trace far from the line means something better than what I wrote.

For peace of mind, I use all metal since the first day and never regret.

Just be careful to not abuse increasing the upper and lower ferrous limits towards the center as it can be counterproductive.

Science or not, I can frankly say that if there's some detectable gold somewhere and You put your coil above it, You'll see it clearly.

Another piece of advice?

Stay conservative with sensitivity cause it seems to ruin all of this beautiful conduct reading ground and buried stuff.

And if noise overcome signals, raise with confidence separation speed up to 6 or 7 if needed.

Less depth?Bulls####

 

 

 

[IBMe]

Not to toot the horn, but Tom Dankowski, who has a forum, could probably give you a more definitive explanation as he worked on the development. Probably has restrictions.

[TampaBayBrad]

1 hour ago, IBMe said:

Not to toot the horn, but Tom Dankowski, who has a forum, could probably give you a more definitive explanation as he worked on the development. Probably has restrictions.

Yes, and his explanation would be in the language the OP may understand. 🙂

CliveHamy, if you would like to check Tom's forum on Manticore, here's the link: Dankowski Forum

It's up to 34 pages now in old school forum format. I have read some people say they have a hard time registering to post.

[IBMe]

new forum

https://www.dankowskidetectors.com/newforum/viewforum.php?f=2

 

[CliveHamy]

16 hours ago, TampaBayBrad said:

As a scientist, you are much more inquisitive about the display than us regular detectorists. By that I mean that I am satisfied with the manual explanation that the top half is for displaying small iron objects like screws and nails and that the lower half is displaying larger flat iron objects like steel bottle caps.

So....how it arrives at doing that I have no idea and (not being mean), I don't care. But I do understand that you would like to know how it is arriving at where to plot the target. My guess would be simply how big of a difference/disturbance in the transmitted signal versus the received signal did the iron object cause due to it's relative size. A nail or screw=small disturbance, larger flat item=larger disturbance when the detector compares it's transmitted signal to what it receives back.

But that's just my non-scientific educated guess. So is that a theory or a hypothesis? 😄

 

[CliveHamy]

Thanks TBB for having a go.