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New Minelab Manticore


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8 hours ago, steveg said:

1.  That "rusty tin infestation" seems to be a "western" thing, more than an "eastern" thing, and so -- with 99% of my detecting of 1800s sites being "back East," I'm not nearly as familiar with that "rusty tin" issue you mention.  I think this somewhat west vs. east disparity is due to the types of containers that food, and other such necessities, were packed into, for folks traveling long distances (often westward) back in the 1800s.  The only time I experienced any of what you are talking about, in terms of that rusty tin issue, has been during the few times I've hunted old miner's camps/cabins, etc. in Colorado.  And when there, I was using a Gold Bug Pro, not FBS.  But, yes, I did experience how those pieces would ID as conductive, and were very "troublesome."

In my limited experience in Western ghost towns it's not just the rusty cans (and worse, pieces of them), although those do play a roll.  Even worse in some places are the pieces of sheet metal (iron composition but possibly originally zinc coated by the galvanizing method).  Sheet metal was quite common in construction, particularly for roofs.  (Sometimes copper was used, but that seems less frequent.)  In some ways these are similar to old crown caps, except for the dimensionality (flat or 2-d for sheet metal and unless severely decomposed, 3-d for crown caps with that raised rim).  Also it seems that rust preferentially attacks edges and maybe this is where a ferrous+non-ferrous readout can really help.  Small pieces have a higher percentage of edge compared to large pieces.

8 hours ago, steveg said:

...My nemesis when hunting 1800s sites "back East" is not the "tin" issue, but the "square nails" issue.

(Note:  The following paragraph is just my impressions; not carefully studied so may be way off.)  For me often the modern rusty nails are worse and I think those might be easier to distinguish.  There seems to be a misconception among many that 'ferrous' and 'iron' are equivalent.  From an historical (and chemical) standpoint that is understandable.  But in metal detecting (as in many pursuits) the lingo that develops and becomes standard isn't particularly conforming to historical or scientific usage.  I think 'ferrous' refers to the magnetic properties if ferromagetic materials.  Iron (and its common alloy -- steel) also has conductive properties and those can dominate the response of a detector.  Where we win is for thin, rusty materials when the ferromagnetic part of the signal can dominate the conductive part.  My hope is that with rusty bits of sheet metal (as found scattered thickly in many Western ghost towns) will give a 'tell' on the new ML Manticore.

As far as the Manticore being an improvement over FBS/FBS2, one possibility is that its better separation when combined with the ferrous+non-ferrous readout (which those earlier detectors perfected) will give it the edge.  Again, just wishful thinking at this time AFAIC.  The Equinox has better separation (from what I've been told -- never had an FBS) but lacks the ferrous discrimination properites of those earlier models.

 

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1 hour ago, Johnnysalami1957 said:

Aurait pu le nommer Equinox 1000. Ou 1500 selon son prix. 

So it would rather be Equinox 2000 given the price.

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15 minutes ago, Geotech said:

FBS2 is VLF with time-domain sampling & processing. There is no PI going on.

Carl,

Would it be possible for you to help me understand a bit more.  My simplistic, non electrical-engineering-trained mind thinks in terms of VLF being "frequency domain" and PI being "time domain."  And I THINK that is correct, right?  And I have a very basic understand of the "trasmit, wait while hysteresis occurs, and then receive" idea of how PI units function...

BUT -- what I have a hard time understanding is if FBS2 utilizes "time-domain sampling and processing," why is that not considered at least "PI-like?"

I would really like to understand this better...

Steve

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1 hour ago, Geotech said:

FBS2 is VLF with time-domain sampling & processing. There is no PI going on.

Do you mean they are doing something like using an inverse Fourier Transform to construct a new time domain waveform out of a number of multiple additive VLF frequencies broadcasted by the coil, and then sample for the target response after the new FFT "pulse" is decaying? But still also sampling in the frequency domain too with the multiple VLF frequencies individually?

Or are you talking about something more basic here? I get confused between the way physics/mathematics terminology is used sometimes in the detector world in ways that don't mean what I would interpret them to mean outside the detector realm.

 

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8 minutes ago, jasong said:

Do you mean they are doing something like using an inverse Fourier Transform to construct a new time domain waveform out of a number of multiple additive VLF frequencies broadcasted by the coil, and then sample for the target response after the new FFT "pulse" is decaying? But still also sampling in the frequency domain too with the multiple VLF frequencies individually?

Or are you talking about something more basic here? I get confused between the way physics/mathematics terminology is used sometimes in the detector world in ways that don't mean what I would interpret them to mean outside the detector realm.

 

Read what I just posted before you did Jason. Carl means it literally - there is no PI going on here.

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1 hour ago, steveg said:

Would it be possible for you to help me understand a bit more.  My simplistic, non electrical-engineering-trained mind thinks in terms of VLF being "frequency domain" and PI being "time domain."  And I THINK that is correct, right?  And I have a very basic understand of the "trasmit, wait while hysteresis occurs, and then receive" idea of how PI units function...

BUT -- what I have a hard time understanding is if FBS2 utilizes "time-domain sampling and processing," why is that not considered at least "PI-like?"

It's a fairly complicated topic that really requires a whole book chapter and a lot of diagrams to explain*. In the old days all VLF designs were frequency domain (or, more accurately, phase domain) and all PI designs were time domain. But BBS/FBS/FBS2 (all really the same basic tech) created sequentially-transmitted frequencies where freq-domain processing doesn't work because the dead time between frequencies would screw up the channel filters. So ML used time-domain processing which, honestly, looks somewhat similar to normal freq-domain sampling. But it's done on ramped-exponential decays instead of sinusoids. From the time-domain sampling you can still get the equivalent of a target phase.

PI is also time-domain (and always will be) and also samples a decaying exponential but it does so during a TX "quiet time" where the TX signal is not changing. With FBS the TX signal is always changing, just like VLF. And with PI, you can never extract a target phase.

26 minutes ago, Steve Herschbach said:

Whether a detector is Induction Balance or Pulse Induction is a function of the electronics and how the current is flowing, continuously, or intermittently. It has nothing to do with processing.

This was a good differentiator until the GPZ came along. In traditional PI the TX current is turned completely off during the RX sampling. In the GPZ it is not, but it is also not changing (the TX current is a bipolar square wave) so the result is exactly the same: there is no changing TX field during RX sampling. So now my definition of PI is a system that receives during a TX dead time, whether current is zero or a DC value. Put another way, during sampling there is no reactive signal.

*Inside the Metal Detector, 3rd ed, Ch 2; pub. 2023 (I hope)

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