Minelab GPZ 7000

[Carl-NC]

Is it VLF? Is it PI? These arguments are pretty moot, because there are no longer two clear pigeon holes to stick things in. New designs are combinations and distortions of old comfortable topologies and the reality is they are neither, at least in terms of what VLF and PI used to mean. Even the distinction between "frequency domain" and "time domain" are blurred. What happens when you take a standard quadrature single-freq VLF and shorten the sampling windows? Is it suddenly time domain instead of frequency domain? Maybe it was time domain all along. Conversely, you could take BBS, stretch the sampling windows a bit, and suddenly it behaves exactly like a traditional VLF.

[Davor]

True. VLF IB is in any case only a special case of time domain. In proper signal processing you simultaneously observe phenomena in both time and frequency domain, and both are only the faces of a same coin.

[crane]

A conventional PI obtains GB by waiting until most ground eddy currents and the X signal are zero or minimal and then subtracting an amplified medium or low frequency sample of the ground signal from a high frequency sample... or... by subtracting a non-amplified combined medium plus low frequency sample from the high frequency sample... and another method combines the high, medium and low frequency samples to cure a problem we couldn't possibly get into here after the X fiasco!!!!
The first two methods rely on the ground response being invariant with time or substantially frequency independent over a range of frequencies, and note that the ground signal and some target signals evolve over time, ie, they are dependent on the history of the TX field.

Single frequency VLF mixes RX phase and amplitude to obtain GB and can only effectively sample one half cycle or less of the single frequency sine wave.

BTW, thanks for absolutely nothing of any value whatsoever Davor!!!!

[Davor]

Likewise. I'm keeping this one for future generations. This amount of garbage is akin to ufox, paul99, and the assorted gang of trolls on a good day.
The level of brown nosing a certain manufacturer whose-name-must-not-be-said, and adoption of all the gibberish their bureau of misinformation vomits is priceless.

BTW, what you said makes FBS/BBS worthless junk. Is it?

[crane]

Likewise. I'm keeping this one for future generations. This amount of garbage is akin to ufox, paul99, and the assorted gang of trolls on a good day.
The level of brown nosing a certain manufacturer whose-name-must-not-be-said, and adoption of all the gibberish their bureau of misinformation vomits is priceless.

BTW, what you said makes FBS/BBS worthless junk. Is it?

I'm not the slightest bit interested in ML as a company or your baseless hate ML crusade, I'm only interested in the technology, and if a competitor comes up with something better then I will switch to it.

On that note, a competitor should have no problem knocking ML off their perch, they only need to employ you and one or two others here who keep telling us that they have all the answers and that ML's IP is prior art.

Errr, when did I say anything that would suggest that any commercial detector is worthless junk?

[Davor]

Here:

... to cure a problem we couldn't possibly get into here after the X fiasco!!!!

BBS/FBS leak X all over the place. So if these are not fiasco, eliminating X is not that much of a feat. Make up your mind

And as you mention a perch it was knocked from - big time - in NATO UXO detecting tests on multiple occasions. That said, the perch spans roughly 3700km south of Darwin, and ... that's it. I'm not saying OZ people are special kind of ... stubborn ... but for experiment simply try to import a single incandescent light bulb to Australia.

What you call prior art boils down to impertinent practice of excessive patenting other people's solutions, and bullying hobbyists. If you are sincere about your interest in the technology, and not only trolling for a certain company, I'm sorry to ruffle your feathers and forgive me for not trusting your good intentions.

[crane]

Here:BBS/FBS leak X all over the place. So if these are not fiasco, eliminating X is not that much of a feat. Make up your mind

And as you mention a perch it was knocked from - big time - in NATO UXO detecting tests on multiple occasions. That said, the perch spans roughly 3700km south of Darwin, and ... that's it. I'm not saying OZ people are special kind of ... stubborn ... but for experiment simply try to import a single incandescent light bulb to Australia.

What you call prior art boils down to impertinent practice of excessive patenting other people's solutions, and bullying hobbyists. If you are sincere about your interest in the technology, and not only trolling for a certain company, I'm sorry to ruffle your feathers and forgive me for not trusting your good intentions.

I was referring to traditional PI and I think you know it, and if you don't realise how much of a feat it is to eliminate the X response in a CW detector designed to detect gold in highly mineralised ground then why don't you just simply admit that you know nothing about the subject?? And if you want to know how X is processed in BBS and FBS coin and relic detectors then do some reading.

As to NATO's UXO detector comparisons, my interest is only in detectors designed for gold but it is obvious from your past posts that you selectively pick negative comments when it comes to ML. We do though see a large number of ML mine detectors being successfully used for detecting gold nuggets, do you know of another brand that might do the same or better???

And ML don't bully hobbiests, the guys you are referring to poked ML with a sharp stick for years, and after their own ideas failed, they then copied everything they thought might be of value from ML's designs. They even boasted about studying the circuits and obtaining what they openly referred to as "ML's secrets".

[Davor]

The pot calling the kettle black. Glad to see your true colours.
Keep on trolling, will be glad to see your back.

[plexi]

I'm new at this so be easy on me I have not worked with magnetism for 38 years but one observation on the VLZ it looks like a low impedance coil hence the three coils
if so that would be a game changer. And as previously stated 6000' of coil wire. The way I see it would be a DD coil just a guess with .042AWG wire it could not take 200 VAC peak
on the rise and fall time of a PI detector unless the mA were very low and lower voltage. A low impedance coil would help noise issues. And would be less prone to high mineralized soil.

Best regards, Steve.

[Chet]

Hi Steve

The 6000' of wire is a little misleading. If you look closely to the open coil picture you will see some braided wire. They use a special woven muti-strand Litz wire for both transmit and receive windings. Litz wire is made up of various numbers of small diameter enameled strands. It can be round or braided into rectangular shapes. For hype someone decided that if you added up the number of strands multiplied by the number of feet it could be approximately 6000 overall feet of wire used in the coils. For example 100 feet of 660 strands of AWG 46 wire would equal 66000 feet of wire.

Have a good day,
Chet

http://www.ebay.com/itm/Litz-wire-66...cAAOSwo0JWMENm

[plexi]

Chet, Thank you for clearing that up for me on wire gauge. I have a learning curve ahead in the metal detector department. I'm looking forward to learning each component function and calibration.
On the GPZ coil does it have one transmit and one receive coil separate or is it three coils in one transmit and receive or a dual coil T & R with a dummy coil.
I use metal detectors as a tool. My goal is to build a PI detector with discrimination for native gold detection that is waterproof. I understand it is cheaper most of the time to buy an off the shelf unit but what knowledge is gained doing things the easy way none.

Respectfully, Steve.

[Chet]

Hi Steve

You can find the GPZ coil layout in figures 6-8 of this patent;

https://www.google.com/patents/US20130154649

Paragraph [0085] has the description of the coil arrangements.

There is a lot of good reading throughout this Forum. Knowledge can become addictive.

Have a good day,
Chet

[plexi]

Chet, thanks So the GPZ has a double D coil receive and a mono transmit coil and at this point in time is the only coil available for the GPZ 7000
I suspect that this configuration would cause more ground noise but minimize eddy currents as to a true mono coil.
So now we get into Flux cutting and Flux linkage.


Best Regards, Steve.

[daverave]

ive been reading through all these things about the gpz detector on this discussion...what does it all matter ??? the fact is the gpz is way over priced whatever bangs and whistles it posseses !!! for a beach detectorist like me it does nothing better on the beach than a $1500 whites tdi pro !!!

[greylourie]

ive been reading through all these things about the gpz detector on this discussion...what does it all matter ??? the fact is the gpz is way over priced whatever bangs and whistles it posseses !!! for a beach detectorist like me it does nothing better on the beach than a $1500 whites tdi pro !!!

What does it all matter? Geotech, learning what makes these devices tick. GPZ on the beach, when you can buy a TDI? Yes overpriced, would be an understatement.