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All-metal mode vs. "zero disc. mode"

Posted by steveg 
All-metal mode vs. "zero disc. mode"
April 27, 2018 08:17PM
Hi all.

On another forum, there's a bit of a debate ongoing about whether the Equinox has a true all-metal mode, or if it incorporates ONLY a "zero disc." capability, but no true "all-metal mode."

My understanding was, a true all-metal mode is a return signal that does NOT pass through a disc./ID "circuit," so to speak, but instead is an audible representation of the "unfiltered" signal. Now, I don't totally understand how the internal electronics work given my lack of an electronics background, so the idea of "circuits" and "filters" are terms I use that I THINK I know what they mean, but hesitate to use them as I am not entirely CERTAIN of my understanding of the nuances/specifics, electrically.

Anyway, my impression was that a true all-metal mode includes a TRUE threshold (not a "reference" threshold), and outputs audibly a signal that has NOT passed through any ID/DISC process or circuit or algorithm or whatever.

However, a statement was made by an Equinox field tester in a thread on the other forum that Minelab engineers say that the Equinox DOES include a true all-metal mode, NOT simply a "zero disc." mode. This confuses me, as even in Gold Mode on the Equinox, you get ID numbers (if I recall correctly) , so some sort of processing of the signal is obviously occurring in order to assign the ID. And so to me, that by definition would mean it's not a true "all-metal" mode.

Can someone speak to all of this, who truly knows and understands it all -- so that I can understand it better for myself?


Edited 2 time(s). Last edit at 04/27/2018 11:55PM by steveg.
Re: All-metal mode vs. "zero disc. mode"
April 27, 2018 08:57PM
Back in the good ol' days, everything was done in analog circuits, and it was analog all the way to the speaker. Filtering, disc, and tone/visual ID were done in analog circuits. Eventually, an ADC and micro were added and things began moving into digital-land. Initially tone/visual ID, and the all-metal vs motion disc filtering remained in analog. Switching between AM & disc modes meant switching in & out analog filtering; generally you could have one or the other but not both.

Modern designs have moved the filtering into digital-land. Raw unfiltered signals are captured by the ADC and after that you can have multiple parallel processing paths going though the micro. This means that ALL THE TIME you can have both the AM and disc signals running and pick-n-choose what you want, when you want, including both. This allows you to see VDI numbers even when running a true AM mode, or to mix AM & ToneID audio in disc mode. Some machines even do rudimentary TID on the static AM signal so you can get (rough) TID info in a zero-motion AM mode.

In short, new design methods are obsoleting old terminology. What is TR? What is VLF? What is multi-frequency? What is PI? A lot of terms no longer mean what they used to mean. In some cases, they never meant what they meant in the first place.

Edit: I have no idea how the Equinox is processing signals, and whether it has a true AM mode or not. Just saying that things are a lot different than they used to be.

Edited 1 time(s). Last edit at 04/27/2018 08:59PM by Geotech.
Re: All-metal mode vs. "zero disc. mode"
April 27, 2018 09:03PM
Thanks for that explanation Geotech.

The question and answer on this thread have that old time feel from way back.

I like it !
Re: All-metal mode vs. "zero disc. mode"
April 27, 2018 09:28PM
Geotech --

That is some really, really good info. Technical enough to correct my understanding, but still non-technical enough that a non electronics engineer like myself can understand.

Thank you!

Re: All-metal mode vs. "zero disc. mode"
April 27, 2018 10:43PM
That's the stuff I miss reading
Re: All-metal mode vs. "zero disc. mode"
April 27, 2018 11:04PM
To add to that..... you can disc out say iron.... which shuts off the audio to the phone...yet they gave us the ability to reduce the tone volume as well... to the point we can turn it off.
Re: All-metal mode vs. "zero disc. mode"
April 28, 2018 12:13AM
In more layman's terms,

if a machine has a true threshold based all metal non motion mode and it reports a number/VID while in that mode = the audio itself is running/reporting thru an unfiltered channel but the VID is running thru a disc circuit/channel in order to report the number you're seeing = like on an MXT in mixed/dual mode or like on the Impact and a few others that run static modes but report numbers on the display (I take it EQ too?) from what you're describing it does/the AM feature it has.

You're hearing the audio in all metal and it's running in all metal feeding you raw unfiltered data but the number is being reported from being ran thru a different channel that allows it to report the number.
Re: All-metal mode vs. "zero disc. mode"
April 28, 2018 12:22AM
Steveg....your f-70 had all metal and gave an id number...as the f-75.
Re: All-metal mode vs. "zero disc. mode"
April 28, 2018 12:31AM
OK MRH, that makes sense. I can see especially how that makes sense in the Gold Mode. The Gold Mode on the Equinox has a true threshold, not a reference threshold, and uses VCO-type audio. But, if I recall, it does give an ID number. SO -- I can see from what you and Geotech are saying, it's a signal being split at the ADC into two separate "streams," or paths, an all-metal path, and another path where a VDI number is assigned. OK, fair enough. An all-metal mode, with ID achieved by running a separate, identical signal through an ID "circuit."

BUT -- what about in regular "Park Mode," for instance? There, you can notch, disc, assign tone bins, or run full 50 tones...and you can run a reference-based threshold if you so choose (by setting threshold volume above zero). Now, in this mode, the default disc. setting from the factory is to disc. out iron, and accept non-ferrous. BUT, there's a button, with a "horseshoe" icon on it -- and if I press that, it immediately turns off the iron discrimination (instead of having to click it off a notch at a time). And so, people will press this horseshoe button, and say "there, I'm running all-metal mode, now." But really, in my mind, I'd say they are more correctly running zero disc. in disc. mode, thus accepting all metals, but it's not "all-metal mode," by strict definition. Now, however, after this discussion, I'm not so sure. Is it now truly nothing more than semantics, to say that pressing the horseshoe button does NOT equate to "all-metal mode," but instead is really running "no discrimination in discrimination mode?" Has this truly been reduced to semantics, now that everything is digitally processed, or is there still something going on where it IS still more correct to say, when hitting that horseshoe button, "I'm running zero disc. in disc. mode" versus "I'm running all-metal mode?"

Re: All-metal mode vs. "zero disc. mode"
April 28, 2018 12:35AM
A question.
If indeed a metal detector has true AM, shouldn't it airtest at longer distances with no disc vs with disc applied? Like how Equinox is setup in detect modes of park 1 and 2, field 1 and 2.

Seems Equinox is yielding no more air test distance when engaging horseshoe for example using park 2.

I haven't checked prospecting modes.

Seems to me this would mean no true AM at least iin these 4 detect modes.

I guess what I am saying doesn't the "less filtering" taking place while using true AM reveal itself even with air ?
Actually in air it will reveal itself moreso vs in the ground (especially higher mineral soil), meaning true AM depth is compromised in higher mineral soil just not as much as disc mode.

Edited 2 time(s). Last edit at 04/28/2018 12:53AM by tnsharpshooter.
Re: All-metal mode vs. "zero disc. mode"
April 28, 2018 12:35AM
I guess that's true, Ozzie. Again, I was so "new" to all of this back then, that I wouldn't have known an all-metal mode from a disc. mode, for the most part! I'm not sure if I can remember back far enough to recall exactly how the all-metal mode behaved, but you are reminding me that it had ID in all-metal mode. As I think about it, the Gold Bug Pro and F19 do, also -- running all-metal, I recall that I'd stil get ID info, up on the "speedometer." So, again, another example of what we are talking about here...

Re: All-metal mode vs. "zero disc. mode"
April 28, 2018 12:37AM
tn --

This partially relates to my last question, above. IS the horseshoe button placing you into an "all-metal mode?" Or is it just a "disc. mode with no targets discriminated...??" OR -- is there really no difference, anymore, in the digital age, and it's all semantics??

Re: All-metal mode vs. "zero disc. mode"
April 28, 2018 12:42AM
steveg Wrote:
> tn --
> This partially relates to my last question, above.
> IS the horseshoe button placing you into an "all-m
> etal mode?" Or is it just a "disc. mode with no t
> argets discriminated...??" OR -- is there really
> no difference, anymore, in the digital age, and it
> 's all semantics??
> Steve

I say at least the field and parks detect modes are just disc mode with no disc.

Just like running F75 in de mode 0 disc. It won't puch as deep in bad soil. Go AM on it and it will.
Same with Nokqta Impact running say di99 mode with 0 disc.
But go general D mode different ballgame.

Actually which VLF detector multi freq that indeed can be run in true AM?
Seems there are few.
White's V3 series and what others?
Does CZ units have true AM? I have never owned or played with.
I need to play with prospecting modes on Nox some more it seems to see what's up here with them in the dept.

Edited 2 time(s). Last edit at 04/28/2018 12:45AM by tnsharpshooter.
Re: All-metal mode vs. "zero disc. mode"
April 28, 2018 12:53AM
I don't have an EQ Steve but from what/how you explain the modes work (other than the Gold mode/s)

I'd say the horseshoe when pushed is how you suspect = it just goes full blown 0 disc but NOT true AM
Re: All-metal mode vs. "zero disc. mode"
April 28, 2018 01:33AM
Something for folks to think about.

Multi freq

How does this work when talking true AM when it comes to Ground Balance.

Like, I could maybe assume the White's V3 series detectors are some what compromised when using true AM using 3 freq multi.

Geotech alluded to something on these units as far as GB goes some time back. Granted running one of the V3 series in single freq could be a different ballgame.

The ground balance on fbs, bbs and Nox are intriguing. How they work. Wish I knew the magic that's done.

You know the more I think about this.
What would if possible would a multi freq True AM really provide over single freq useable?

In my mind it's almost like the use of multi freq (no true AM) allows more filtering to be done and actually arrive at a better place vs using single frequency. Like multi freq (each freq tx data and received) can be filtered more, but indeed has other transmitted freq data transmitted and received to compare. Hence in the end you arrive at a better place. Maybe I'm off base here.
The reason I say this, is witnessing what I have using multi on the you know what doing multi to single freq doing head to head comparisons. Seems multi freq harder to fool vs single freq.

Edited 3 time(s). Last edit at 04/28/2018 01:53AM by tnsharpshooter.
Re: All-metal mode vs. "zero disc. mode"
April 28, 2018 03:17AM
Yes...... the EQX Prospecting Mode-1 & 2 are true all-metal modes (with VID...... and higher group of Freq's utilized).
Yes...... the CZ has a "auto-tune" all-metal mode...... which is the truest definition of "all-metal".
Re: All-metal mode vs. "zero disc. mode"
April 28, 2018 05:59AM
When they designed the Equinox, they should have added a true all metal button for each frequency or each mode. That would be very handy. Maybe we'll see it on future models.


Edited 2 time(s). Last edit at 04/28/2018 06:10AM by Badger in NH.
Re: All-metal mode vs. "zero disc. mode"
April 28, 2018 06:12AM

Thanks for your reply. So, that implies that there IS still a "more than just semantics" difference between "all-metal mode," and a "zero discrimination" mode...

Re: All-metal mode vs. "zero disc. mode"
April 28, 2018 10:43AM
Steve......i see the separate reporting of digits..... but the other part disc, isnt that nothing but what the machine lets you hear? It still sees everything and is affected with coil shut down i believe. According to the manual..... AM and no disc are one in the same. They have done a few things different that is just now being looked at like the question of AM vs no disc...... and it seems to be a silent running machine with the ability to run a reference threshold (noise to me). Then theres the ability to reduce volume for each bin. Seems they have played with the audio more with this one.
Re: All-metal mode vs. "zero disc. mode"
April 28, 2018 02:38PM
Steve-G , thanx for bringing up this good topic. Geotech & Michigan-relic-hunter : Loved your inputs !!

Cal-cobra and I have had this discussion, during long drives to md'ing spots . And to add to the confusion: There are machines (like the one being discussed here) that has/allows for an over-lap. The Whites Eagle was like that, where you could have simultaneous all-metal, yet the chosen disc. #'s coming in as well.

And some people used to make the mistake of thinking they were achieving all-metal depths WHILE discriminating. But no, it didn't work that way: A fringe target would fall into the iron (or whatever you'd chosen to disc. out) range. Hence, yes you got the target "deeper" (if you want to call it that). But no, you weren't getting the TID for the deeper fringe ones. It was easy to get lulled into THINKING you were going deeper in disc, but that was merely a psychological trick: The fact that you're getting a fringe whisper, would subconsciously draw you to "double-check" various spots. Eg.: smuch the coil closer, center it better, double check, etc... And then ... sure ... you'd THEN perhaps get the TID to chime in. But the reality was: Whether or not you'd been in the cross-over mode, did not increase the resulting depth of when/where targets could come into the disc. depth range.

Same for something like the Explorer : If you use ferrous, and open up the screen entirely (nothing disc'd out), then you're hearing everything. So it could be argued that you're in "all metal". Well, .... yes and no : The deeper fringe targets would come in with the nail-grunt whisper. But they could simply be deeep conductors that are too deep to trigger the TID on.
Re: All-metal mode vs. "zero disc. mode"
April 28, 2018 03:17PM
dew --

I don't know. I don't know for sure if it's that simple. YES, the Equinox excels (in my opinion) at giving us lots of ways to slice and dice and adjust the audio, as you well noted. But as far as the "doesn't disc. mode 'see it all?'" I don't know if that's the case...

Here's how I've always seen it. If you are in a true threshold-based all metal mode, you hear the threshold "hum," which -- if ground balanced properly -- is an audio-based representation of the "pure" return signal, with ground signal "removed." Right? I've always understood a true threshold as a real-time, audio-based "monitoring" of exactly what is being received by the coil, though with ground signal "subtracted out." Now, the savvy hunters have always talked about how even a tiny "waver" in the threshold, IF perfectly ground balanced, could be the hint of either a tiny target, or a fringe-deep target, right?

So, let's move over to disc. mode. I have always understood it that there has to be "enough" of a return signal, with sufficient "information" to be available, so that the machine's processor can run calculations, or whatever, so as to be able to assign an ID number, and/or a Tone ID to. This seems to make sense, based on what I have experienced, and what I understand. In other words, to calculate an ID -- either tone, or visual -- the machine needs enough "information" to glean from the signal to "examine" and "process." And my understanding has been that there can be a situation where on the very weakest of return signals, insufficient information can be gleaned from the signal to assign a proper tone or a proper number to that signal.

And so, I have always understood it that a true threshold-based all-metal mode will almost always be the deepest mode to run, IF you know what to listen for, because that tiny, subtle threshold "waver" can, if weak enough, be too "weak" of a signal to assign EITHER a VDI number or a tone ID to it. On an Explorer, and on the Equinox (and I'm sure other modern machines are similar), I have of course seen times where I hear a tone (i.e. the machine apparently had enough "info" to assign a tone-based ID to the signal) but no VDI number shows up on the screen (signal too weak for the algorithm to confidently assign a digital ID number, presumably). So, I would conclude that for some reason, some machines are able to assign an "audio ID" to a weaker signal than they can apply a "digital ID number" to.

BUT -- the question remains...do you reach a point where that "all-metal mode threshold waver" type of signal is simply too weak of a signal to assign even a tone ID to, let alone a digital ID number? Such that, having that TRUE all-metal mode can be, for a very experienced user, who knows how to keep a very accurate ground balance, a slightly-more-sensitive-to-the-weakest-of-signals mode -- i.e. the absolute "deepest" way to hunt, if you are focused enough to carefully listen for the most subtle hint of a threshold waver, and recognize that it may be a literally "fringe deep" target?

I don't know, and this whole premise is based on something that -- if not true, in today's electronics world -- would make this whole discussion fall apart. And that is, IS THERE A SUCH THING, anymore, of a return signal that is truly too weak to assign a tone or visual ID to, BUT is still "strong enough" to give you a little "threshold waver" in all-metal mode?


Edited 4 time(s). Last edit at 04/28/2018 03:24PM by steveg.
Re: All-metal mode vs. "zero disc. mode"
April 28, 2018 04:17PM
Glad people are starting to discuss this on the EQUINOX..

Yes the Equinox has a true all metal threshold based mode in prospecting...

It is a single channel in that mode ..like a raw audio feed ..it hears everything and just send it to the speaker..Unlike in a disc mode that takes that raw feed and phase shifts and processes it for a beep to happen...

The advantages to all metal threshold based mode is the true raw audio feed and the ability to hear it all in continuous feed..that's the rise and fall of the target through nuanced dark to light feel..true modulation...and the ability in the soil to see deeper since its not taking the audio and having to phases shift it which can rob some depth in the processing..

The recovery speed setting in the prospecting mode is more like a S.A.T. speed

So we talk about wanting disc circuits to be able to bleed enough so we can hear rejected targets intellegenty for unmasking....and offer a chance for items to break through the audio if the the dirts harsh ..that's what the Prospecting mode does inherently ..

We learned along time ago even on analog to use all metal to our advantage,,Even on the old whites 5900s we or I Know myself ran them in all metal mode and just watched the needle of the ID since it still reported while in all metal...Ieven hunted in harsh iron like that as the all metal was way faster retune speed between targets VS the 4 filter disc mode..

The Equinox utilizes the disc mode Visual ID in all metal prospecting mode and takes advantage of it by allowing that ID number to be Nulled..Luckily the Visual ID on the Equinox is very exacting especially in the lower end and especially in the nail break range,,So while we are getting our live audio feed of the soil and targets in it though the threshold waivers...ifa number through the disc channel side pops up it blanks out the audio whenever the disc number coincides with your notch you have applied to the ID..But that null will be triggered form the DIsc circuit and is a slight lag behind the raw feed you getting...Plus we get to hear More of the target before the machine nulls the exact ID of the target...Where say on the DIsc side the audio BEEP is generated along with Visual ID and its how should I say a snapshot or even composite I.D./tone that is fed to the speaker...the All metal live feed gives us info till the Disc side processes it and gives a composite snap of target then the machine Nulls that target for ID reading..so while we have the processing taking place we are listening to the live feed of targets..it doesnt care if its reporting a nail or a silver dollar and really has no way to know..It just wants to signal a target as it should..then if a ID pops up the audio is nulled while that ID is there ..Utilize a zero Iron Bias and its working on the disc circuit not the all metal circuit.So now we have a Bleedy Iron circuit along with a Live feed raw report...We hear it all except the nails if we use the iron null feature then we turn it all the way down on Iron bias so its Bleedy..and we have taken the best of of both modes and combined them depth and nuance and unchained raw feed and just added a slight amount of Bleedy disc to overlap on top of it in the nail range..

My video shows this very well...in depth and in unmasking. you should be impressed by a large coil seeing the nail board and it takes Prospecting to achieve it with some slight filtered nail mask thats it...

and yes the depth in Prospecting is also deeper just like running a F75 in allmelal or old school 5900


“I don't care that they stole my idea . . I care that they don't have any of their own”
-Nikola Tesla

Edited 1 time(s). Last edit at 04/28/2018 04:18PM by Keith Southern.
Re: All-metal mode vs. "zero disc. mode"
April 28, 2018 06:29PM
Keith --

Great post, but a good bit of it is over my head/hard to picture, since I lack your experience (the part where you are talking about using the prospecting mode, talking about the ID showing up and "nulling" the VCO audio in the Gold Mode, and how to interpret this, as you describe it, "bleedy" iron circuit "blended into" the VCO audio of the Gold Mode...

I guess I'll have to play with it, to see what you are talking about, but even then, I would have a hard time wrapping my brain around the implications of what I was hearing, and how to exploit those nuances to "do what you do," in terms of leveraging it for improved detecting success...

I'm too much of a "mere mortal," Keith, to relate to the "dark arts" you use to unmask targets in iron...

Re: All-metal mode vs. "zero disc. mode"
April 29, 2018 12:53PM
Keith & Tom = Straight From The Horses Mouths !!!!
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