Minelab GPZ 7000

[Davor]

Thanks Davor all book marked except this one, its no longer found.
A Fast 4-D TEM System for UXO Characterization
http://www.estcp.org/documents/techdocs/UX_0105.pdf

You may find it here: http://www.dtic.mil/get-tr-doc/pdf?AD=ADA442592

[deemon]

So, it is as I suspected, and this technique is not designed to work with short decay constant targets.

Hm ... why not ? The key parameter here is a flyback pulse duration . So if you need , for example , to feel a target with 1uS TC - just make the flyback pulse about 1 uS and enjoy . Less turns in the coil ( made of a good Litz wire ) , less capacitance in parallel , pump the current and frequency ( up to 100 kHz , for instance , or even more ) , use a very fast transistors - and we'll get a good device for very thin targets .... but of course , if the target TC is equal to the salty water TC - we cannot separate them using TC as a criterion . And another tip , comparing to the classic PI technology - increasing the main sample delay ( in classic PI ) is equal to increasing the flyback pulse duration ( in square wave PI ) .

[Qiaozhi]

Hm ... why not ? The key parameter here is a flyback pulse duration . So if you need , for example , to feel a target with 1uS TC - just make the flyback pulse about 1 uS and enjoy . Less turns in the coil ( made of a good Litz wire ) , less capacitance in parallel , pump the current and frequency ( up to 100 kHz , for instance , or even more ) , use a very fast transistors - and we'll get a good device for very thin targets .... but of course , if the target TC is equal to the salty water TC - we cannot separate them using TC as a criterion . And another tip , comparing to the classic PI technology - increasing the main sample delay ( in classic PI ) is equal to increasing the flyback pulse duration ( in square wave PI ) .

That was my interpretation. It doesn't help to eliminate ground when your intended target has a very short time constant.
Also, you did say this: "... and we can say that this feedback mechanism really desensitizes our detector for such kind of a ultra-short targets."

I guess what I'm really trying to understand is the main benefit of this technique. Does it provide greater depth? If that's not the intention, then what is it?

[Carl-NC]

Deemon, your CCPI method is different than ML's and probably inherently better. This is why folks need not get so wrapped up with patents, there are usually several ways to get there. ML's approach requires careful compensation of ground effects and hence their patent to cover that, but other CCPI methods steer clear of the whole issue. Thanks for sharing all your work.

[deemon]

That was my interpretation. It doesn't help to eliminate ground when your intended target has a very short time constant.
Also, you did say this: "... and we can say that this feedback mechanism really desensitizes our detector for such kind of a ultra-short targets."

I guess what I'm really trying to understand is the main benefit of this technique. Does it provide greater depth? If that's not the intention, then what is it?

I meant that if we need to ignore some kind of targets - we can set the device parameters in order to make it unsensitive to them . So it's a benefit , not a drawback . And about a ground elimination , you see - there is a big difference between a ground ( probably having a ferromagnetic properties ) and a salty water ( having a low conductivity ) . So when my intended targets has a very short TC , I can have a problem with a salty water ( if its TC is close to the targets TC ) , but not with the ground . Ground elimination is an inherent property of this circuit , just because of its principle of operation - as I explained before .

And what about the benefits of this technique - in theory it must go deeper than a classic PI with the same coil and the same power consumption . And it must have better ground tolerance . Of course , I need to perform many experiments to prove it ... I'll do it all when I'll have enough time .

[deemon]

Deemon, your CCPI method is different than ML's and probably inherently better. This is why folks need not get so wrapped up with patents, there are usually several ways to get there. ML's approach requires careful compensation of ground effects and hence their patent to cover that, but other CCPI methods steer clear of the whole issue. Thanks for sharing all your work.

But you see , Carl , how this CC TX idea does lead , quite logically - to a 3 different signal processing algorithms .... it's really amazing . When I started this research , I wanted to assemble only one device , but then I had seen that I need to test all 3 approaches and choose the best .... so the theme appeared to be significantly longer that I thought before As for me , I believe that the third alghorithm is the best ( with its auto-balance feature and all this correlation stuff ) .... but it's a most difficult to solve also . Some problems are so specific that there aren't any well-known solutions , and I needed to invent something special ... anyhow , I'm already near the finish of this project .

[Qiaozhi]

I meant that if we need to ignore some kind of targets - we can set the device parameters in order to make it unsensitive to them . So it's a benefit , not a drawback . And about a ground elimination , you see - there is a big difference between a ground ( probably having a ferromagnetic properties ) and a salty water ( having a low conductivity ) . So when my intended targets has a very short TC , I can have a problem with a salty water ( if its TC is close to the targets TC ) , but not with the ground . Ground elimination is an inherent property of this circuit , just because of its principle of operation - as I explained before .

Thanks, now I understand.

And what about the benefits of this technique - in theory it must go deeper than a classic PI with the same coil and the same power consumption . And it must have better ground tolerance . Of course , I need to perform many experiments to prove it ... I'll do it all when I'll have enough time .

Yes .. what the results are in the real world would be very interesting.

[greylourie]

Here is a M/L Knowledge Base article.

[Kev]

Ho,
Some may find these interesting,
At around 6 Watt hour, there's a lot of power jammed into those very short pulses.
No physical difference between pulses for Extra Deep and General timing, must be in the processing.

Sorry for cruddy scope images, also no damping or true magnitude.

Cheers
Kev.

High Yield Pulse

High Yield Waveform


General Pulse

General Waveform


Extra Deep Pulse

Extra Deep Waveform

[greylourie]

Thanks for posting up those images. Very nice scope you must have. It is intriguing to see such alternating short duration pulses. When viewing the pulse train from afar, to my uneducated eyes, they almost look like flyback periods. Reminds me of something PiTec posted once. For years MikeBG spoke of an old "gradiometer-like" coil and principle. Seems to follow similar pattern, measuring the difference between two receive signals.

From videos and reports, it displays some astounding depths for the smallest of targets. Horrible machine. You lucky fellow.

[Kev]

Yep Lourie there's nothing new under the sun, either natures done it, or someone else's thought of it before.

How it's applied in real life is what makes the difference...........yeah horrible machine indeed, maybe if some of deemon's ideas make their way into the next revision, it'll then be a real beastie, and not a heaftie only.

I think the DOD coil maybe the Achilles heal of this machine.......when you consider the whole TX energy is released in such a short duration, the grounds got to complain wildly me thinks.

cheers Kev

[greylourie]

deemons device offers lots of potential for what and when things are measured. Feel bit guilty not following through.

[Qiaozhi]

deemons device offers lots of potential for what and when things are measured. Feel bit guilty not following through.

Are you saying that Deemon's concept is being commercialized?

[green]

Ho,
Some may find these interesting,
At around 6 Watt hour, there's a lot of power jammed into those very short pulses.
No physical difference between pulses for Extra Deep and General timing, must be in the processing.

Sorry for cruddy scope images, also no damping or true magnitude.

Cheers
Kev.

High Yield Pulse
[ATTACH]33929[/ATTACH]
High Yield Waveform
[ATTACH]33930[/ATTACH]

General Pulse
[ATTACH]33931[/ATTACH]
General Waveform
[ATTACH]33932[/ATTACH]

Extra Deep Pulse
[ATTACH]33933[/ATTACH]
Extra Deep Waveform
[ATTACH]33934[/ATTACH]

What is the scope measuring?

[greylourie]

Are you saying that Deemon's concept is being commercialized?

Who is saying what exactly ? Can you attribute your question to anything my above post might have said ? Bit surprised, that coming from Geotech admin. Especially when your posts are something I relish reading for their clarity of purpose.

I'm quite startled !