Why a discriminating PI?

[Kitsune]

The only viable known method that I'm aware of is ADR (Atomic Dielectric Resonance), which is unavailable technology, Radar World Ltd.

Neaaat, first, the thread was started with slightly trollish declaration "all PI and whatever discrimination is crap", followed by repeated "REAL detectorists ALWAYS dig up everything" and finished with subtle bullsh*t technology/company advertisement.

[bakergeol]

As an owner of a GS5 and a Ferrous Hound I have been following this thread with interest. My point is no matter what machine you bring out of the closet it will have weak points(GS5. Ferrous Hound, Big Vlf). You simply must understand each machines weak points and adapt.

For instance, the GS5(I do not yet have the upgrade yet) does ring a high tone on some new bottlecaps down at the beach. Well considering you are only dealing with a narrow range of low conductors (up to roughly 1/3 ounce)for this tone appling reverse discrimination is an effective tool. So with 2 iron test positions on the GS5 with an reverse discrimination option you have effective iron ID with depth.

I can't dispute the remarks made about the Ferrous Hound. It is an effective magnetometer but with limitations all mags have. Yes it is depth limited for small flat iron and deep flat iron. For me the point is so what? It's value to me is that I employ the Ferrous Hound with the GS5. It is a great "heads up" machine. Instead of testing every signal with the GS5 GB mode (you have 2 GB mode positions and a reverse discrimination option)I have my FH to tell me which signal to test. So only bottle caps below 6 1/2"(Ferrous Hound limit) do I have to apply the GS5's iron options. It is a great time saver as I run the GS5 and the mag at the same time. It is also a great "hot" rock identifier because of the great shape "hot" rocks have.

Granted discriminating PIs in the future will make all of the above obsolete and cumbersome. Indeed when the next generation is offered I will one of the first to buy one. Until then I figure I have the best combo for iron ID presently.


I feel the GS5 is giving me a view of the near future. Discriminating PI's will be the future for all the high end arenas. The age old problem is that the deeper you go the more ground mineralization your VLF reads. This means that good targets will read "iffy" with depth. As PI's are not effected the way VLF's are in mineralization you will not see this with PIs. The key is that your tones will not change with depth regardless of the mineralization. The unquie sound character I receive with a unique pulse delay setting and GB mode for a zinc penny is not going to change with depth. You are not going to get "iffY" signals with depth or questionable iron signals with a discriminating PI.

Just my 2 cents
George

[Paul]

Neaaat, first, the thread was started with slightly trollish declaration "all PI and whatever discrimination is crap", followed by repeated "REAL detectorists ALWAYS dig up everything" and finished with subtle bullsh*t technology/company advertisement.

Care to take a dip into the world of science and apply some data to prove your statements or shall you continue your emotional charade of fuzzy logic backed by nothing?

[Paul]

I see George is the first non-fuzzy logic thinker to reply. We'll see if anyone follows.

Granted discriminating PIs in the future will make all of the above obsolete and cumbersome. Indeed when the next generation is offered I will one of the first to buy one. Until then I figure I have the best combo for iron ID presently.

I agree with just about all you say George. You could be correct in the above statement. Time will tell. One thing's for certain, nobody has provided any science to prove that any PI, VLF, IB, or such combinations can distinguish between a piece of iron against an appropriate sized nugget in mineralized ground. On the contrary I've provided the science as to why such units cannot achieve such a task.

Paul

[ElectroNovice]

ElectroNovice,
That seems to make my point; i.e., dig everything.



That method is not accurate. Again the machine can only give you a probability. That probability is worthless in the hands of a novice. If the professional nuggetshooter knows his area and knows there's a high probability of old iron chunk in the area and if the machine is saying it "looks" like iron then it probably is. Yet, ask any good professional detectorist and he'll tell you he digs everything.
The method you mentioned is not accurate because you can have a nugget sitting next to a chunk of magnetite, which is not uncommon.

Paul

Paul have you read all the papers on SAM or the hundreds of papers on UXO detection by EM or the thousands of papers on EM geophysical prospecting? So what if a lump of gold sits near a lump of maghematite or magnetite.The Tx off magnetometer survey will record this as a magnetic anomaly either geophysical due to the ferromagnetic minerals or due to ferromagnetic iron,the lump of gold will have little effect on the local magnetic field.

The TX on magnetometer survey will then record this as a huge magnetic anomaly many orders of magnitude above geological background ie a conductive target. The magnitude of the Tx off magnetic anomaly and the nature of the localised perterbation of the magnetic field at this anomaly will enable with a high degree of probabilty to predict the nature of the buried target,ie ferrous/ non ferrous. If you don't want to use a magnetometer with TX on you can of course use a Pi purely in recieve mode inside a large Tx loop and a well designed Pi will not respond to the geological anomaly. The reponse of the buried target can then be tested by varing the Pi Rx sample sample delay which will effect the amplitude of the recieve signal.As the sample delay increases the amplitude of the recieve signal will change DIFFERENTLY for ferromagnetic and non ferromagnetic targets again enabling a user to predict with a high degree of confidence if the buried target is ferrous/ non ferrous.If you understood enough about Pi and EM and had done enough reading you would understand this.There are also some recent documents which you should read eg,"A Multidisciplinary Analysis of Frequency Analysis of Frequency Domain Metal Detectors for Humanitarian for Demining' a Phd thesis by Claudio Bruschini and others which show how in EM we can use the in phase and quadrature reponse of EM detectors to remove the ground reponse and predict better the nature of the buried target.

I suspect you have been on other forums and are about to hit us with a promotion of your "gold only technology" is this not the case?
ElectroNovice

[Paul]

ElectroNovice,

Take a piece of iron. From the viewpoint of the PI this iron has magnetic properties in addition to being a good conductor of electricity. Actually normal PI's don't detect magnetic fields. Rather they detect photon interaction. I simply added the magnetometer to the thread just to be safe. Now that iron has permeability and an RL time constant. I can easily replace that piece of iron with a piece of metal, say aluminum, and a piece of magnetite of appropriate size and your PI cannot tell the difference. I can easily match the irons RL time constant with by the aluminum. I can easily match the irons magnetic properties with the magnetite. Although, as mentioned, you can theoretically get a spectrum fingerprint, but it would have to be in the MHz as in 100+ MHz. As mentioned, such fingerprints are not accurate. I'm not sure how else to say it. A PI, even with some sensitive magnetometer can be tricked.

Tx off magnetometer survey will record this as a magnetic anomaly either geophysical due to the ferromagnetic minerals or due to ferromagnetic iron

And so will a piece of iron. Iron is magnetic just as magnetite is magnetic.

,the lump of gold will have little effect on the local magnetic field.

I never mentioned anything about that, but now that we're talking about it we can say that the magnetic material will indeed change the golds RL time constant and the gold will affect magnetic materials. The only signal that metal cannot effect magnetic material is DC, but there is no such thing as DC. The gold simulates the eddy current that a piece of iron would generate. Can you see what I'm saying? I am saying that we can simulate / replace a piece of iron with two pieces -> metal such as aluminum & magnetite. The metal simulates the RL time constant. The magnetite simulates the magnetic properties found in iron.

The TX on magnetometer survey will then record this as a huge magnetic anomaly many orders of magnitude above geological background ie a conductive target. The magnitude of the Tx off magnetic anomaly and the nature of the localised perterbation of the magnetic field at this anomaly will enable with a high degree of probabilty to predict the nature of the buried target,ie ferrous/ non ferrous.

The probability would only come in the form of an experience person who knows the area. If the area is prone to high amounts of iron then sure the detector can accurately predict, but that's not a broad term of "accurate." The broad term of "accurate" would encompass all situations. If I can come to your place and trick your PI detector every time then that is not accurate.

I suspect you have been on other forums and are about to hit us with a promotion of your "gold only technology" is this not the case?
ElectroNovice

Wow guy. The clear and precise answer to your question is "NO, I have nothing to sell here or any metal detecting related forums or sites." Once again, I'm seeking on the field data.

Paul

[ElectroNovice]

Why a discriminating PI?

I take on board what you say Paul. But in gold hunting particularly for large nuggets there is no substitute for experience,research and common sense. In Vic Australia any deep targets in truly virgin goldfield ground are almost always gold.Most trash items are usually very shallow.

Also highly reliable discrimination in Pi detectors is possible at least according to Dave Emery with his Pulse Devil. Perhaps he can come aboard and join this discussion?
ElectroNovice

[NC-Dave]

Hi folks. First Paul's comments about discriminating PI's. The Pulse Devil is indeed my design. It can accurately identify iron as it does not just look at the resistive component of the signal. Several samples are taken during the transmit on time which when compared to the resistive signal which is measured during the transmitters off time allow for highly accurate discrimination. The extra reactive information measured during the on time makes this possible. As to the depth of the Pulse Devil. I won't make any claims about that but will wait for others to report from their testing. Let's just say that it goes deep.

ElectroNovice surely you must have some old mine camps around? I am told that they are full of nails etc. If however all you work is virgin ground then you are quite correct in what you say. You are also dead right in saying that there is no substitute for experience, research and common sense.

[ElectroNovice]

Hi folks. First Paul's comments about discriminating PI's. The Pulse Devil is indeed my design. It can accurately identify iron as it does not just look at the resistive component of the signal. Several samples are taken during the transmit on time which when compared to the resistive signal which is measured during the transmitters off time allow for highly accurate discrimination. The extra reactive information measured during the on time makes this possible. As to the depth of the Pulse Devil. I won't make any claims about that but will wait for others to report from their testing. Let's just say that it goes deep.

ElectroNovice surely you must have some old mine camps around? I am told that they are full of nails etc. If however all you work is virgin ground then you are quite correct in what you say. You are also dead right in saying that there is no substitute for experience, research and common sense.

Thanks Dave,
So you are looking at both the inductive and reactive signal components for Tx on and off using balanced TX and Rx coils? Yes we do have old camps containing heaps of iron trash and some damm good gold and relics as well!
ElectroNovice

[Kitsune]

Care to take a dip into the world of science and apply some data to prove your statements or shall you continue your emotional charade of fuzzy logic backed by nothing?

Well, dear Mr. Paul, about discrimination you already received a bunch of replies, you feel that discrimination is not an useful feature for you, a lot of other people find it otherwise, great. Just - that' s not at all "a world of science", but only a personal preference and detecting style. I very thoroughly do not care about your obsessive wish to dig up every rusty nail in hopes that it might be huge gold piece.

Now about subtle bullsh*t technology advertisements - according to Occam's razor, it's your, not mine, duty to provide information that would back up your claims about Radar World Ltd and Atomic Dielectric Resonance (c) which supposedly works using phonons. Whatever is seen on the Net somehow does not leave an impression of it being real (Uhh, I wonder why? ). And don't be shy about your explanations being "extremly technical" - this is Tech forum after all. Although, if the content of end product of grass digestion in the large cattle will be big enough, they might be more appropriate in Remote sensing forum.

[Carl-NC]

...and finished with subtle bullsh*t technology/company advertisement.

Actually, plugging products and companies is not taboo on these forums. The way I look at it, if a product is worthwhile, then folks should know that. If it is not, then I suspect that fact will also be revealed, and folks should know that, too.

- Carl

[Paul]

Hi Dave,

It can accurately identify iron as it does not just look at the resistive component of the signal.

No offense intended, but I have to question your definition of "accurately." If I can trick your Pulse Devil every time then is that accurate? Also, such a machine will tend to miss the larger finds. It may save digging time, but good finds are something of a rarity. You might sell a lot of machines, but in the end the pros. will be right back to digging everything.


You say you're measuring the reactance during on pulse time, but I will show how you are making several assumptions.

Measuring the reactance of a nugget is no secret. This can be done on either the rising or falling pulse. After the pulse you can measure the RL time constant. So if you know the L component and the RL then you know both R and L components separately, but that buys you nothing in far as iron discrimination. I will tell you exactly how a piece of metal such as aluminum or gold can appear just like a piece of iron.

Also there are methods of obtaining the magnetic properties of the material, but that can also be simulated with a piece magnetite.

A piece of iron could easily be one of the following:

Sizes are relative to the piece of iron in question:
1. A large common nugget within the vicinity of a piece of magnetite.
2. A medium size purer nugget within the vicinity of a piece of magnetite.
3. A small size purer nugget, but thicker, close to a piece of magnetite.
4. A small size aluminum, but thicker, close to a piece of magnetite.

Those are just a few examples. Of course the size could very depending on shape and purity.


Furthermore, any piece of iron can be simulated / replaced and trick the Pulse Devil by manually making a metal (such as aluminum or gold) disc of appropriate size and shape. Iron contains three appreciable properties: Magnetic, Resistance, and Inductance. Take any piece of iron and these three components are precisely matchable to a metal disc such aluminum with the appropriate diameter and thickness within the vicinity of magnetite. Here is how:

The L component relative to the R component is matchable by changing to diameter of a metal disc. The R component relative to the L component is matchable by changing the thickness of the metal disc. The thickness also varies the L component to some degree and the diameter changes the R component, but together any RL variation is obtainable. The net detected field strength is variable by rotating the metal disc, but that is not the issue at hand. If by some small chance your Pulse Devil detects magnetic properties such as contained in iron then that is matchable by placing an appropriate magnetite within the vicinity of the metal disc.


Here is yet another way your unit can be tricked or shall I say the poor person trusting the machine. There very well could be an actually piece of iron, but next to that iron could be a really nice nugget or find. :-)


Dave, no offense, and A+ on trying to improve PI disc., but IMO no PI is going to get really good detectorists to not dig finds. Perhaps for a while they might be tricked, but eventually they'll be right back to digging everything. It's a nice feature, but I see it as a gizmo wooptido ... no offense intended.

Paul

[Paul]

I very thoroughly do not care about your obsessive wish to dig up every rusty nail in hopes that it might be huge gold piece.

Wow guy, btw, key word was "professionals" dig everything. Stop trying to focus on just me-- professional detectorists dig everything.

Now about subtle bullsh*t technology advertisements

Go jump off a pier guy. It was not an ad. Gee, if we all utilized your fuzzy logic mentality then we could say Dave is simply here to advertise his Pulse Devil.

according to Occam's razor, it's your, not mine, duty to provide information that would back up your claims about Radar World Ltd and Atomic Dielectric Resonance (c) which supposedly works using phonons.

There you go again with fuzzy logic. Occam's razor does not dictate such. Life is always a two way street. Furthermore, Occam's razor is not abstract thinking. You will never find a genius utilizing occam's razor. Occam was not a genius. Genius, as in Einstein, Tesla, etc. Why don't you take a little lesson in the abstract thinking process:
http://en.wikipedia.org/wiki/Abstract_thought

Whatever is seen on the Net somehow does not leave an impression of it being real

Words that go without saying.

And don't be shy about your explanations being "extremly technical" - this is Tech forum after all.

Perhaps you're under the impression I'm from Radar World. Well I am not, nor do I have access to ADR technology. If you chose to ignore all the press releases, public demonstrations, and articles written on Radar Worlds ADR technology then that's your limitation. I clearly stated that the discussion of phonons and ADR are beyond the scope of this site, period.

Paul

[willy]

Dig everything?

Talk about faulty premises. Pro's will dig everything, therefor, those who use disc. are not pros. How 'bout I turn it around... inexperienced detectorists dig everything. See, the veiled insults can go the other way too. There are a number of places I know of where someone can be thrown in jail for "digging everything", given that there's an extreme amount of iron (nails & such) down deep (12"-24"). Now, an inexperienced detectorist might hunt in all metal there and end up basically rototilling the whole area.. until the cops show up. If a person were to strictly limit oneself to nugget detecting, there are situations where disc. can, and generally will, be used. These are the areas of virtual iron trash dumps where said trash is also very deep. If I'm digging in nice easy sand, I might dig everthing; but if it's tough digging with roots and rocks and hard ground with deep targets, I'm more likely to use disc. Spending 1/2 hour digging a trash target can be a waste of time when a person contrasts that against getting a good target by using disc. Sure, there will be target masking and inaccurately ID'ed targets that are passed over, but the probability of getting a good target, and more of them, can be higher. To put it another way, I could be sluicing for gold and get a 99% recovery rate if the slope is gentle, water flow moderate, and small amounts of material run. On the other hand, I could run a steeper slope, puke the water through, and shovel like an SOB.. with somewhere around a 90% recovery rate. In the latter case I'm running 10-20 times the material.. losing a bit more , but getting a whole lot more in the end. That's playing the odds and the same applies to metal detecting. I have a number of friends that are professional prospectors/detectorists that, like me, have at least a quarter century of experience detecting and they use disc. when required... but wait.. they can't be pros; they're using disc. Silly me. ...Willy.

[bakergeol]

Paul

Your quote " A small piece of iron or aluminum can look just like a medium or large nugget or a small pure nugget. Surely you dig everything, right Carl???"

Well that statement for me is half right.

First I am not a tech guy nor do I wish to become one- I use a MD as an escape for my hi-tech job. So I am going to talk as a user not a tech guy.

Using the GS5 nuggethunting, you cannot confuse the smallest or the largest piece of iron at any depth for a gold nugget which is more than roughly 1/3 ounce in size. No ifs or buts about this just using tones. I can distinuish an AL can from a ferrous can at any depth the detector is capable of(subsitute large gold nugget for AL can). The "iffy" portion comes in when you are dealing with gold less than roughly 1/3 oz which is where most gold is found. You have certain steel types such as some new bottlecaps or bic lighters- heat treated steel which is different than regular iron and produces the same tone as small gold. Hence my interest in using reverse discrimination on the GS5 using adjustable pulse delay for the gold below 1/3 ounce as well as with the Ferrous Hound. Of course my experiences are on the non-upgraded GS5(Eric is upgrading mine now)so it will be interesting to see how my new model will perform.

With regards to "iron masking" - Well life is tough- get used to it. Some detectors are better than others. My GS5 can distinuish a dime just touching a bottlecap as nonferrous and ferrous using a small coil so I assume it is above average.

By the way I would love to have one of Dave's Pulse Devil's in my closet. PI guys must start to think like VLF guys. Serious VLF addicts have numerous VLFs because each will work best in certain areas. Likewise with a GS5 and a Pulse Devil in my closet I will be ready for an diverse number of locations and conditions.


George