The discriminating pulse induction detector is needed. we are in the stone age.

[RingProfessional]

Will it ever be possible to make such a machine is it impossible? does anyone know if metal detectors are going to get any deeper?. I wont waste any more money on buying new top level vlf's because theres nothing in them with regard to coin detection depth. I need to detect small coins at a foot in dry soil but the most i can get is around 7 - 8 inches. Finding small coins at depth is what sorts a good detector from a bad one. In the mean time i will still keep dreaming about the DISCRIMINATING PULSE INDUCTION METAL DETECTOR.
I will be the first to buy such a machine if ever one is made that actually rejects iron and other bits of trash. Getting coins past 8 inches with id is so hard if not impossible with a vlf. The metal detecting industry is going to die within the next few years in my opinion because as sites get worked out people are going to loose interest. Most of my sites are worked to death, but i know deeper coins are to be got but until a detector is made that will give me another 6 inches extra depth on coins then i wont buy another vlf discriminator ever. Some kind of display that shows the shape of a target would be the best form of discrimination ever made as we could then actually see what it is we are about to dig. We are still in the stone age with our technology of metal detectors .

 

[Cody]

The Explorer is a discriminating pulse induction metal detector! That is how it is patented, how it operates. The analog pulse induction detector switch the power supply across the coil to create the pulse. The Explorer and Sovereign use a square wave to pulse the coil.

Pules induction does not mean a foot of depth in discrimination but is time domain instead of frequency domain. Pulse induction has to have ground compensation just as any other detector. What is very unique about the Explorer is how it compensates for soil minerals. It takes about 3/4 of one patent to explain this and then another patent to explain the frequency domain aspects of the detector.

I think it is convenient to simply call the Explorer a hybrid although that is only partially correct. It is actually a very modern unique pulse induction discriminator. If we get stuck in thinking an analog pule induction which does not discriminate then we are several years behind the invention of pulse induction with discrimination as patented by Minelab and invented by Candy.

The Explorer will discriminate to within about an 1/8" of maximum depth. A major barrier to depth is not discrimination but that magnetic particles in the soil can retain magnetism if the transmitter pulse is over driven. So driving the tx coil hard is detrimental to depth and soil rejection. The same problem is true of the analog PI, modern PI, and VLF.

 

[Steve(MS)]

The 2 final frontiers are greater depth and target separation with the ability to see thru trash. I have just bought a vintage detector to check out it's ability to see thru trash but the weather has not been cooperating so I will get to it when I can.

 

[RingProfessional]

I guess i will keep my explorer for the next 30 years then.

 

[Cody]

I don't think depth is the issue unless we think of depth WITH discrimination. I recall how deep the first VLF would detect and how small the pieces of iron it could hit. We could use a larger coil and wear ourselves out pretty quick on deep targets. Depth became an issue when it was depth with discrimination. I don't think there is a way to use the current multiple or single frequency technology and get much more than what we have other than a little more with a larger coil then we run into coil size to target size problems. I don't what I would do with a machine that was sounding off on targets at 2 feet the size of a dime or smaller in a park. My guess is we would all end up being banned from public hunting areas. I don't think a USABLE magnetic field can be radiated from a coil that is going to do more than what we get now. Depth is extracting fainter signals from what is already contained in the composite signals and rejecting the trash. The other way to achieve depth is to use a larger coil to radiate the TX field. If it was just more power then engineers would have done that a long time ago with larger power supplies.

I agree, I would not be trading my Explorer off in the near future. I feel like I am seeing about what we can be done with the Explorer, Sovereigns, DFX, and now it looks like the T2 may be one to watch. However, we are still looking at very small differences in what has been achieved in depth for years now. I am sure you are like so many of us and always looking for the next evolution that will give us some real serious increase in depth with discrimination.

 

[Steve(MS)]

We have to examine the what the consequences will be with more technology, that is if we had a machine that could tell us the exact size and shape of an object then I think a lot more people would be getting and using detectors, then if you think it is difficult to find a good place to detect now, well most places would be wiped out with no hope of finding anything good, as it is, no place is completely hunted out. As it is, there will always be different ways of thinking out the process of the challenge of detecting, those "hard to detect areas are the ones to seek out because the other guy gave up on it or only was going for the "quarters".
Steve(MS)

 

[RingProfessional]

I never thought about it that way that if a metal detector had 100% accurate discrimination then sites would be cleared out more - true.
Do you know what i hate more than pull tabs - well the answer is i hate chewed bits of aluminium cans as it sounds like gold or other bits of jewellery. Seems like most of the parks over here are strewn with the stuff. :angry:

 

[Steve(MS)]

There are some sights I frequent with the same problems. One thing you may want to pursue is trying to find some old house places and/or old church sites,old fields,parks, to detect also so that you will have diff. sorts of sites to visit. That will keep it more interesting and you can experiment with strategies. HH and take care.
Steve(MS)

 

[RingProfessional]

From what i have read about it this is a pulse induction discriminating metaldetector for coin hunting that uses modified vlf circuits to discriminate iron and other trash. What do you think to the idea of a pulse induction machine and a vlf combined.

 

[Charles (Upstate NY)]

n/t

 

[Charles (Upstate NY)]

The engineering types covered this question pretty well on the PI forum a while back. But if you want to test this go swing the Explorer over some black sand infested soil, now swing a real PI over the same soil.

 

[Cody]

It is patented as PI detector as designed by the Minelab Engineers and recognized as such by the US Patent Office. I have no desire to offend the others with this statement but the most basic perusal of the patents discloses that it is a PI detector.

My guess is their confusion is more one of tradition than reason since the older PI detector had the power supply switched across the coil. Using that as a fundamental design consideration I can see how they fail to understand a PI that is driven by a rectangular pulse. However, nothing we say one way or the other will alter the fact that it is a rectangular pulse drive time domain PI detector.

Look at the patent and see what you think.

 

[Steve(MS)]

I have been following this one since July of last year, also it has to prove to be effective on land to be of interest to many of us. It sounds promising but don't sell all your units quite yet, however if it works as promised it will make most vlf's obsolete.
Steve(MS)

 

[Charles (Upstate NY)]

Suggesting that the Explorer is a PI machine and compares favorably to PI's in the area of depth and ability to work in black sand and wet salt beach conditions is the type of misinformation that confuses people. I can't think of a single person who uses both a PI and the Explorer who has said they compare, they say the PI kicks the Explorers butt in depth especially on low conductive targets.

Minelab clearly identifies their PI machines as PI machines and the Explorer as a FBS machine. They also compare the Explorer not to PI machines but to VLF machines. I read some of the patents, the Explorer seems to be sampling during the transmit period not after like PI's do. Explorer coils are sensitive to more conductive shielding methods like nickel paint and foils, PI's are not. Black sand can suck the depth right out of an Explore, PI's ingore it.

Here's what an engineer who actually designs VLF and PI machines had to say about the "is the Explorer a PI" machine debate...

Many people are fooled by the difference between a square wave pulsed VLF and a PI detector. The truth is that an on-off square wave is just as usable in a VLF detector as is a sinusoidal transmit signal.

A square pulse contains energy at it's fundamental frequency as well as at harmonic frequencies. This is used to advantage in multi-frequency detectors.

Some advanced pulsed VLF detectors use a series of long and short pulses to provide the equivalent of transmitting a plurality of frequencies. All of these VLF detectors sample at least twice during each transmit cycle A first sample is taken from the receive signal at close to zero degrees and a second at ninety degrees relative to the phase of the transmit signal. Most multi-frequency detectors sample the receive signal twice for each frequency.

Each type of target provides an output signal from the demodulators which changes with different transmit frequencies. Multi-frequency detectors can thus make a finger print so to speak for each type of target as they collect more target information than single frequency detectors.

A single frequency VLF measures the ratio of the two demodulated signals. The ratio of these signals is often output as a number and is displayed as a target ID. Measuring the ratio of the two demodulated signals also provides the detector with it's discrimination ability.

A Pulse Induction detector is different from a VLF in as much as it transmits a signal by switching the battery voltage directly across the transmit or transmit - receive coil depending if the detector is using a balanced coil such as dual D or a simple mono coil.

Switching the coil across the power supply circuit causes a very heavy current to flow through it. the current causes a magnetic field to form around the coil. After a specific time period the coil is switched out of the circuit. A further short delay is provided so the circuit can settle down before one or more samples of the receive signal are taken. These samples are taken after the PI's transmit period ends unlike the VLF which samples during it's transmit cycles or pulses.

 

[Cody]

Charles, think for yourself and look at the patents. The Explorer is in fact a hybrid PI detector. Don't turn it into this detector vs that detector. The Explorer is in fact a PI detector, is hybrid, and designed to operate with far less waste of power than the old analog design. One cannot read the patents and fail to understand that much less an electronic engineer unless they are in denial.

I enjoy your post and comments but unfortunately you missed this one a mile.

 

[Captain Kirk]

I see it like Charles explains it. Does the patent actually claim that the Explorer is a PI detector? I think that the first step is to define what actually characterizes the PI operation. Only after doing that can we really answer the question. Until we do that we are in a battle of semantics.

HH,
Glenn

 

[Cody]

Glenn, you are correct and one thing I have decided it to drop the issue. Good to see you posting. I am always concerned when I don't see guys like you for a while as I learn so much from your professional experiences.

Everyone has a pet theory that in reality sucks! Ha

 

[Steve(MS)]

that vlf is called induction balance. The pi on the other hand doesn't have to be balanced between 2 coil windings, at least that is how I understand it. There may be some pi's that have more than one coil, don't know if they would be "balanced" and if they are then that would then cause a problem in defining the two.
Steve(MS)

 

[Steve(MS)]

Garrett in one of his promos regards more than one freq. detection system "pulse induction",in "what you should know about multiple frequency". Maybe it is best to call the Explorer a pulse balanced induction detector? OK, that is all I know, which ain't much.
Steve(MS)

 

[Captain Kirk]

Steve,

I claim no expertise in this area, but I do have an opinion about what really characterizes the pulse induction process. There is a pulse than "induces" eddy currents in metal objects in the target matrix. Then, the induction process is turned off and the coil picks up the magnetic field from the eddy currents. The process is roughly similar to that used by bats and dolphins.

In the Explorer the stimulus and response are taking place simultaneously. The receiver coil is measuring how the magnetic field is being disturbed by the target matrix. Eddy currents distort the field in one direction, while magnetic material distorts it in the opposite manner. For iron objects the magnetic effects occur quickly during the pulse, while the eddy current effect takes place a little later in the pulse (because of the self inductance of the target) and then falls off with time depending upon the conductivity of the target.

HH,
Glenn