ADVANCED TRAINING

As the one who did the above mentioned 'test', I never intended to indicate that our results would equal a 21 inch burial. I can see it was poorly worded and misleading. I was thinking of hunting over ice plant, rocks etc. where you cannot get close to the ground. I am a novice at primary level testing and like many, learn from mistakes. Clearly I did here. I was thinking clearer than I spoke and between knowing what I was thinking and anxiously seeking to post results I was pretty excited about, I blew it. I stand with the raw data, but take the interpretation with a huge chunk of Himalayan salt.

Past(or)Tom
Using a Legend, a Deus 2, an Equinox 800, a Tarsacci MDT 8000, & a few others...
with my beloved, fading Corgi, Sadie

PastTom....I did not intend to high light this either. I’m just have some idea how difficult your beaches can be. I was the one who combined those results not you buddy. Thanks to Tom for great info so no one is miss lead especially some one new wanting one of the machines. But.... I am serious about wanting to know what you guys are finding....especially the gold. I know it can be one of those....it’s there or not situations just like we are having. I got 2 cents today in the water.... buddy got 35 I think.

Tom..... it was NOT AT ALL..... to be a verbal lashing/spanking. In fact...… you triggered me to think of 'how' folks interpret things. VERY good reminder! So/hence; my Segue into said response.

So Tom...... how much EMI comes just from the ground? There has always been that question...... "how far off the ground should i GB ..... or does it matter". I believe most of that had to do with ground EMI. Isnt there such thing as conduction (physical contact) and radiated EMI..... one affecting low freqs and the other high freqs?

Very little (if any) EMI comes from the ground. Now...… there is one large exception. If there are buried power wires underground...… this is one of the worst types of EMI..... that (normally) will completely render any detector 'useless'.

You should Grnd Bal...…. within an inch or two off of the ground. ((( About an inch …. seems to present the greatest attributes..... in fairly bad dirt ))).

Another.....electric fence on a farm.

Things that eat a lot of battery power:

1. Pinpoint button
2. Selectable lower Freq's
3. Backlight
4. External Speaker usage

Antenna...….. vs ………. Coil.

* A antenna is usually in the form of a stick. A rod.
* It is "open-ended".
* Electromagnetic energy radiates/emanates from the ends.
* The electromagnetic energy leaves the antenna...….. and never returns. . . . . . . just like a bullet leaves a gun..... never to return.
* The electromagnetic energy from an antenna.... traverses: to-----and-through "near-field" …. then into "far-field"..... and beyond; to infinity.

+ A coil is in the form of a loop.
+ It is a "closed-loop". (A coil is NOT "open-ended"). It is a 'closed-circuit'.
+ Magnetic energy (NOT electromagnetic energy) radiates/envelops around the loop.
+ The magnetic energy does not leave the loop...… it stays within the confines of the loop.
+ The magnetic energy (by physics) is incarcerated within the confines of "near-field" only. This magnetic energy does not reach/traverse into the "far-field".
+ Even the encircling magnetic field generated by the coil..... is a 'closed-loop'. A 'closed-circuit'. The easiest way to visualize/picture this is; the 'closed-loop' energy-field is in the shape of a doughnut. The magnetic field encircling the coil..... does not leave the coils field...……. unlike a bullet from a gun. It stays within the confines of the loop. These eddy currents (magnetic lines of flux) encircle the doughnut in a closed-loop fashion. If you increase the transmit power..... you are merely increasing the size of the closed-loop..... and NOT departing "near-field". By laws-of-physics...….. you are incarcerated... to-and-within... the confines of "near-field".

There's a bit more to this; yet, for all intents, purposes and …… ease-of-explanation …… I post this data.

And...… right now...… I am not smart enough to merge the two differing technologies. Subsequently; we are incarcerated into "near-field". We can only recover targets a mere handful of Centimeters deep. (Whereas: Archaeologists are recovering targets: Meters deep).
As a detectorist...….. on a daily basis...…… we are finding targets 100-years-old …….. all the time.
As a Archaeologist... on a daily basis...…… we are finding targets 1000-years-old...….. all the time.

NASA-Tom,

In reading through this, and thinking of "antennas" and "far-field" ideas...Doppler radar comes to mind. With Doppler radar technology, we can transmit an electromagnetic pulse from an antenna, and then measure extremely minute phase shifts in the received electromagnetic radiation (those miniscule phase shifts having been imparted by the "motion" of the target), so as to then glean/extract meaningful information about the target through analysis of the changes in the physical properties of that received radiation. Could there not theoretically be an analogous way that could be conceived, where we transmit EM radiation into the ground, and -- sort of analogous to receiving/measuring/deciphering a tiny, minute phase shift in the EM wave imparted by a object in motion -- measure something akin to a "phase shift," i.e. some type of tiny/minute change in the physical properties of the transmitted EM wave, but imparted in this case NOT by the MOTION of the target, but instead imparted by the specific electrical properties of the target -- and then extract and decipher information about the target?

Steve

NASA-Tom Wrote:
-------------------------------------------------------
> Antenna...….. vs ………. Coil.
>
.......
> As a detectorist...….. on a daily basis...…… we ar
> e finding targets 100-years-old …….. all the time.
> As a Archaeologist... on a daily basis...…… we are
> finding targets 1000-years-old...….. all the time.


Good, basic information but your last comments are a red-hearing. Detectorists are finding things thousands of years old all the time (in places with the proper age). Also, archies come in with excavators or teams of workers who dig down feet of overburden before even beginning their search. Archies simply take a likely looking area and begin digging test trenches and expanding from there. Can you imagine what we could find if we operated like that?

OK, back to the tech talk....

steveg Wrote:
-------------------------------------------------------
> NASA-Tom,
>
> Could there not theoretically be an analogous way that could be conceived, where we transmit EM
> radiation into the ground, and -- sort of analogous to receiving/measuring/deciphering a tiny, minute
> phase shift in the EM wave imparted by a object in motion -- measure something akin to a "phase
> shift," i.e. some type of tiny/minute change in the physical properties of the transmitted EM wave, but
> imparted in this case NOT by the MOTION of the target, but instead imparted by the specific electrical
> properties of the target -- and then extract and decipher information about the target?
>
> Steve

GPR works on backscatter, but discriminating coins from rocks is a challenge.

NASA-Tom Wrote:
-------------------------------------------------------
> Things that eat a lot of battery power:
>
> 1. Pinpoint button
> 2. Selectable lower Freq's
> 3. Backlight
> 4. External Speaker usage

Maybe we are getting closer to detector eating battery power is nominal..Batteries seems to be ever evolving and getting more powerful and lasting longer in lighter smaller packages!

[smallcaps.com.au]

In the future I hope to see a Pulse TYPE unit as powerful as a GPX in a Deus size box and maybe even some disc thrown in for good measure through processing

Keith

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

Geotech --

Understood. "Simple" backscatter, I realize, would present that difficulty (is it a rock or a coin) -- just as "non-doppler" weather radar has a similar challenge (i.e. it is tough, on a single, static image, to decipher a large building from heavy rainfall -- as both simply "backscatter" some of the transmitted EM radiation).

HOWEVER, when analyzing that "phase shift," it adds that additional dimension where now, we have some additional information about the target (i.e. is it "moving," in this case), that helps differentiate that rain cloud, from the building. In other words, to "borrow" a term from detecting, we can "discriminate" a stationary target, from a moving one, because -- the TARGET, the "recipient" of the EM transmission, acted on the EM wave in such a way as to alter the wave's physical properties/characteristics in a specific way. In other words, "information was added." And subsequently that "added information" can then be extracted/gleaned from the received EM radiation, to learn something about the target. I know you understand all of this, Geotech, but I'm elaborating so that those not familiar with "Doppler radar" might understand what I'm thinking here...

So, my thinking is, is there any "alteration" of an EM transmission that occurs, when encountering certain targets, such that while being backscattered, there has also been some physical alteration to the properties of the EM wave...alterations that can be gleaned/extracted for target ID purposes? Specifically for gold/silver hunters, are any of the chemical/electrical properties characteristic to noble metals, properties that might "leave their fingerprint" on the physical characteristics of an EM wave -- such that, when backscattered to a receiver, that fingerprint can be deciphered, and used as some sort of "discrimination circuit?"

Steve

Geotech Wrote:
-------------------------------------------------------
> steveg Wrote:
> --------------------------------------------------
> -----
> > NASA-Tom,
> >
> > Could there not theoretically be an analogous wa
> y that could be conceived, where we transmit EM
> > radiation into the ground, and -- sort of analog
> ous to receiving/measuring/deciphering a tiny, min
> ute
> > phase shift in the EM wave imparted by a object
> in motion -- measure something akin to a "p
> hase
> > shift," i.e. some type of tiny/minute change in
> the physical properties of the transmitted EM wave
> , but
> > imparted in this case NOT by the MOTION of the t
> arget, but instead imparted by the specific electr
> ical
> > properties of the target -- and then extract and
> decipher information about the target?
> >
> > Steve
>
> GPR works on backscatter, but discriminating coins
> from rocks is a challenge.



Edited 2 time(s). Last edit at 12/30/2018 08:00PM by steveg.

Steve...….. RF into dirt IS possible; yet, there is a multiplicity of challenges/problems to overcome. Time permitting...… I do want to discuss this; yet, at a different time. Right now...…. I want to start to 'touch' on:

Mineralization.
Another huge performance impeding (sometimes crippling) inhibitor in the detecting world. Without going too deep into Physicist mode...….. let's look at some basics. The Earth is a ball/sphere with magnetic poles...… and comprises of iron ores... that inhibits us detectorists. Magnetite (Fe3O4) being the strongest. . . . . and can be reddish/brown/black in color. Hematite (Fe2O3) is primarily red in color. And Maghemite (also Fe2O3)…...can be yellowish/brown in color. Hematite and Maghemite are derivatives of Magnetite (the parent). And there's plenty of other minerals/iron-ores that impede our intended performance. Since Magnetite is the parent/origin unto which we 'basis' our gauging/measuring concern in the detecting World...… even to the point where Dave Johnson/Fisher launched the first on-screen measuring gauge (which revolutionized detectorists thought-process) ……. which has broke through even more barriers of "understanding"...… via tremendously enhanced "awareness" to the detecting community. We knew mineralization was bad...… and was hurting us; yet, now we have a 'measuring-device' to commonality-basis our communications with other detectorists around the World...… to see/witness/learn of each others differing conditions. Soooooo………. we have now learned... the World has infinite differing/varying dirt conditions …. that causes folks to have dramatic performance deltas/differences from one another. We have ALSO learned ….. there is a commonality; that being: 'iron based'. Yes; we've known this for a long time; yet, …… it is in the higher order-of-magnitude of ""awareness"" …… especially in the (design) engineering labs ….. that have caused us to take a different 'look' at our current-day methodology unto which we (challengingly) hunger to resolve, discover, invent.

Who are we ...….. (and) ...….. Where are we ,,,,,,,,, Today. We are still:
* generating a magnetic field (from a coil)
* on a magnetic core Earth
* looking for diamagnetic and paramagnetic implements
* in an ocean of interlaced ferromagnetic targets
* within the body of magnetic dirt.

(((Sounds paradoxically self-defeating)))

Bottom line: Pulse Induction ……. so far...….technologically...…. is the best we can do ….. in highly mineralized dirt. And Pulse Induction still presents its failures/limitations......along with its reasonable attributes. It appears Minelab's GPX series does the best for severe dirt...…. with "some" (crude) form of ferrous/non-ferrous ID (4500, 4800, 5000).
The Tarsacci is adding a new/different twist to the equation; with its set of limitations and capabilities. . . . . . and quite different from the rest. . . . . with its full ID capabilities.
Single freq units have come a long way; yet, performance still lags behind...…. in bad dirt.

In fairly bad dirt: What we see (technologically) today is:
Detector 'A' may see a dime to 12"..... and ID it reasonably/properly..... to 7".
Detector 'B' may see a dime to 11"..... and ID it reasonably/properly…. to 8".
Detector 'C' may see a dime to 7" …. and ID it reasonably/properly..... to 2".
Detector 'D' may see a dime to 10"..... and ID it reasonably/properly..... to 8".
And all of the (above) detectors may air-test a dime to 12".

Due to infinite varying conditions around the World...… these numbers will also vary; hence, the large 'span' that folks report (and can cause a point-of-contention & disbelief) that we commonly see on these forums.

IT IS DIFFICULT TO GIVE A FINITE ANSWER...… FOR A INFINITE VARIABLE.
(((But...…. we're working on it))).

The internet has certainly brought us a wealth of knowledge...… and a rapidly shrinking gap of "what works" and "what doesn't work"...… in a overall-aggregate wide-span condition(s) around the World. In short order...… It has also dramatically helped Physicists & Engineers "see" what is needed in the marketplace.

Um...wow, that’s heavy Sir.
Metal detecting truly is a science and even more complex than we realize. In over 3 decades of hunting I’ve seen it progress tremendously, especially in the last 10.
I wonder what the next 5 may bring?

Aaron



Edited 1 time(s). Last edit at 01/01/2019 04:56PM by Aaron.

Well, Aaron the Tarsacci for one . Yes we are in a golden age of detector advancement and my pile of 'obsolete' detectors is growing, but my arsenal of practical tools is too!

Past(or)Tom
Using a Legend, a Deus 2, an Equinox 800, a Tarsacci MDT 8000, & a few others...
with my beloved, fading Corgi, Sadie

Even thou....14” and SOME depth for that air gap in difficulty sand on that ring is impressive. Here in Fl who would need a PI?

Off-the-cuff thought:

In the early 1970's...… the standard coil was a 6" coil.
In the mid 1980's...…. the standard coil was a 8" coil.
In the early 2010's..... the standard coil was/is a 11" coil.

In the 2030's...… a holographic projection coil. :-)

Dont forget the 9.5" of the 1990s. New tech meant more depth....has nothing to do with the larger coil...Ha....joking



Edited 1 time(s). Last edit at 01/03/2019 01:44AM by Arkansas.

I'd disagree. I'm pretty sure that in most cases a larger coil does have something to do with increased depth.

The GPX is also very susceptible to EMI. It doesn't take much to render one nearly useless. My buddy and I hunt together a lot. He tends to want to stick close to me, which drives me batty some times cause I can start to hear his machine interfere with mine. Depending on what channels we are running, I can hear him sometimes as far as 50 yards away. The problem is, he likes to hang out about 15 yards from me. Haha. Thus is a big issue at the organized relic hunts where 300 people have a GPX and there may be 100 or more of them hunting the same 30 acre field/hot spot. There's simply not a clear channel you can go to, to get away from the warbling and motorboating. People are always amazed at how there can be 10 or more hunts on a property, and there still be easy relics in the same areas that got pounded. That's why. More relics are found on the 3rd and final day after lunch than the first two days combined because half the people leave at lunch on the 3rd day. Meaning not as many people and everyone spreads out. Can hunt more better like that.

Despite the emi problem from other machines, powerlines, fences, even weather changes...there's nothing better in mineral and nasty ground that we have found than the GPXs.

With age....comes wisdom (hopefully). Over the past few decades...…… I have made the following observation (including: first-hand):

A CDE (Chief Design Engineer) invents/creates a 'miracle product'. BUT...…………. then: The C.E.O. ……………… or Marketing Department...………… or some time-continuum/time-pressed Corporate deadline...……. or mass-production incarcerating restrictions; severely infringes upon the CDE's 'miracle product'. Then: This 'miracle product' succumbs to: mediocrity status. Starting with the C.E.O. .,.,.,.,.,.,.,.,.,.,.then the marketing department...………... all the way to the product end-user: We all suffer...…. by having to accept a "no-longer: miracle product"; but/rather...….. succumb to accepting a 'normal/average' product...…….. NEVER missing what we 'could have had'. NEVER missing the large technological advancement...….... because of:

YOU DON'T KNOW...….. WHAT YOU DON'T KNOW.

We have no idea: "how good it WAS". ""How good it could have been"".

Sooooooo……….. the time-continuum/World presses forward: Unknowingly. Unsuspectingly. In to the World of mediocrity.

Let's proceed into a example of: "What If".

What if Carl Moreland has created such product. Yet Tom Walsh, Marketing Dept. (or whomever): Cripples Carl's (and Alexandre Tartar) 'miracle product'. We (the end-user) would never know what we 'could-have-had'. I can only hope Tom gives Carl more reign. This may require: Finding the way to efficientize mass-production. Create a new non-standard R.O.I. Model. Taking additional (calculated) risks. Creating a (unknown/unsuspecting) paradigm-shift...….. that 'appears' to be a: paradox. What if Tom was the: Miracle Product pathway.

I merely use Carl/Tom/Alexandre as one example. The list is not finite.

Here is something that is noble/commendable about a certain creed/breed...…. yet; a paradox:
From one Chief Design Engineer ….. to another (direct competitive) Chief Design Engineer: We all want to see tremendous success. Yes; there is 'competitiveness' ……. but/however; If one CDE comes out with a tremendous technological invention/advancement...……… all other CDE's "applaud" the one CDE. We eternally embrace human-advancement & technological-advancement. Barriers/walls are dropped. Human pride trumps technological pride. This is forever-commendable.

This is ADVANCED TRAINING for certain/specific (unsuspecting) folk.

In furtherance of the human race.

i agree 1000% Tom. If it tuneable the average Joe can use the machine out of the box with factory settings...... but if its dumbed down at its very peak .... we really have put ourselves behind by years. Edging a machine up every .... lets say 3 years, knowing it was capable of doing the very same thing the new model does back then is a set back to me. The concern that people wont buy a powerful machine because it requires a little effort makes no sense..... when all you have to do is run in factory settings until you have the time on the machine and you get that AH HA moment. But dragging a machines ability out over years based on the initial capability just isnt the way to make that great leap forward faster. It may sell the same machine for 10 years but that same machine would have likely sold more machines over that 10 years..... and increased competition to compete. It seems some are content to have the top machine for years ..... before they start thinking about releasing the tech they already had in the machine in the first place. We are definitely on the same sheet of music. Id like to see them work on improvement..... not status quo. Putting machines on the back burner..... just because you have one on top isnt progress either.

I would add sometimes the project can be bigger than the DE's capabilities. ie, wrong guy on the job. End result is a flop for a product and a clueless DE.

Happens.

HH
Mike

George Payne. Why do the top engineers never stay at one company?? The only limit of an inspired engineer is the companies leash length....Marketing

As a retired military guy i can see the need for change. Our regulations might have been standard...... but there were as they say more than one way to skin a cat. It was an education each time i moved learning/teaching different ways to do the very same thing. It was good to get a fresh perspective from other points of view and get some NEW ideas worth exploring. At the end of the day..... everyone benefited... and sometimes even these standards changed.

If the noise cancel for the ctx3030 is done wrong can that have an impact on the vdi's being wrong/off of what there suppose to be?

It can.... by so can GB, depth, near targets even sensitivity or coils.

So what's the right way to noise cancel the ctx?

Have to remember the CTX isn’t like the Nox. Is has channels with random freqs so IMO auto is best. It has an excellent noise cancel a feature I believe is better than the Nox.