GROUND BALANCE ( without the ground :-) )

[boilcoil]

Bravo Moodz,
Really great.
But I expected a balance of the hot stone without any hot stone.

[Altra]

Nice work! I am curious do you do the number crunching in the FPGA or a co-processor?

[moodz]

Bravo Moodz,
Really great.
But I expected a balance of the hot stone without any hot stone.

Thanks BC ...that hot rock was chosen as a test specifically because it wont ground balance out on top shelf commercial detectors ... the place it came from is a gold field in Australia littered with this type of rock so I will be going back there.

[moodz]

Nice work! I am curious do you do the number crunching in the FPGA or a co-processor?

Thanks Altra. All the crunching is done in an FPGA ( xilinx spartan 400 ). Early on this year I was very tempted to just grab the data from the ADC using the FPGA and simply stream it to an STM32 or PIC32 ... however I ended up persisting with the FPGA to avoid a birdsnest of boards.

The older ADC I used has a parallel interface and it was just easier to crank the data out using an FPGA than a CPU.
I also had the boards ( 24 bit ADC and FPGA ) sitting on the shelf from ten years ago ready to go ... from a PI project ... so it was convenient.
However there is no specific reason why a CPU could not do the same ... and would make coding the user interface easier.
I could run a soft processor in the FPGA but then would start running out of resources and probably have to add external memory and need a bigger FPGA.

[Altra]

Thanks for the detailed answer and updates

I wonder if one of these could be useful?

https://www.ebay.com/itm/11612712717...3ABFBMqMTql7tl

[moodz]

Thanks for the detailed answer and updates

I wonder if one of these could be useful?

https://www.ebay.com/itm/11612712717...3ABFBMqMTql7tl

Yes ... I have seen those before. I have 5 or 6 of the old FPGA and ADC boards so would need to move to an updated platform.
I need an ADC replacement also ... any suggestions?

I still need to do some field testing on the goldfields to prove out the new scheme.

[Carl-NC]

I'm intrigued... any details coming or are you thinking about a patent?

[moodz]

I'm intrigued... any details coming or are you thinking about a patent?

Hi Carl ... I think you will appreciate the method used. Are you interested in a collaborative patent ?
I am happy to split the AU market from the US market LOL.

[JoyJo]

Here is a video showing operation of the "ground balance without the ground" .

The demo is a VLF IB and have not had time to verify but it should/may work on PI detectors also.

It uses an algorithmic method that I have discovered. ( ie not look up tables or fairy dust )

Enjoy.

https://youtu.be/idVP0gRar54?si=lGSRHIzjKnjHTJ8g

The mode of operation is similar to static. And how will your product work in littered places where there are targets made of different metal, different sizes and different shapes next to each other?

[moodz]

The mode of operation is similar to static. And how will your product work in littered places where there are targets made of different metal, different sizes and different shapes next to each other?

You may have to clarify what you mean by "static" ... is this non motion or SAT off or something ? However ...

Interesting question .... my design goal was to make a VLF IB with ground balancing that had sensitivity the same as a PI detector
... that is the best you can hope for with a PI detector. Never found a PI with reliable disc.

I am using a "new??" principle to resolve the ground balance issue without having to reference the ground .. which I believe is new and different from what is done and understood now.
There is no new physics just new interpretation resulting in a new method.

I can say that the method should not impact discrimination methods currently used so the "new" GB method should coexist with existing methods.
In fact you can still use the existing GB methods as well as this new method.

In summary this detector is a deep punching VLF IB that has GB and is at least equal to/exceeding the best PI detectors available that does not require a ground sample to determine the operating point.
I would expect to add full discrimination also. ( but I think that is unrelated to the GB method ). For deep targets the the general rule is "digem all".


... and I haven't touched multifrequency yet .... early days.

[moodz]

I'm intrigued... any details coming or are you thinking about a patent?

After a couple of days slaving over a hot computer ... an Australian provisional patent is now lodged.

You may be interested to know that one of the principal prior art citations is your patent US 9285496 B1.

[Orbit]

Hi Modz! Turning off the ground without ground, if I understand it, implies that the balance point is determined in advance, and at that point the detector no longer needs to be adjusted on the ground?! But still adjust the operating point using hot rocks and ferrite?

[moodz]

Hi Modz! Turning off the ground without ground, if I understand it, implies that the balance point is determined in advance, and at that point the detector no longer needs to be adjusted on the ground?! But still adjust the operating point using hot rocks and ferrite?

I know there are many types of "ground" .... the ground I was most interested in nulling out is ground with a high ferrite content and hotrocks ( aussie gold fields ).
A conductive ground ( seawater for example ) requires a different technique ( SAT in my case as the conductive ground looks like a weak but constant target).

To answer your question though ...the balance point is determined through an algorithm without being near a ground and the detector then cannot "see" ferrites or hotrocks and there is no need for further adjustment or fine tuning as I have been able to achieve a very exact balance and it is probable that the theory of exactly what ground balance is will have to be revisited. The question may also arise why no one has seen this possibilty before ... maybe they have but did not realise what it was since the effect appears as a signal error ... but is in actually the ground cancellation value ( even if ground is not there ).

So you may also wonder why the detector has a ground balance button at all. The reason for this is that if there is a drift in the some parameter ( eg heating in the front end or slight change in coil parameter due to mechanical expansion etc ) and due to the high sensitivity then you would need to hit the ground balance again.

[Orbit]

Thanks Modz! Yes, I assumed it was an algorithm! Of course, props like a hot ferrite rock are used for testing.. It's all very interesting, I've read Karl's patent several times, but as you say, something always slips by or we stick to predetermined rules, and the rules are there to be broken!

[boilcoil]

Bravo Moodz,
You are a real magician.
I am really glad of your success. I wish you always to be the best and do new and new things.

that hot rock was chosen as a test specifically because it wont ground balance out on top shelf commercial detectors ...

Indeed, some PI detectors with very early first samples (most notably gold-seeking detectors) and fixed delays for GB samples may not be able to balance certain targets by adjusting the gain in the GB channel/s.
But if we reverse things (fixed the gain and change GB sample/s delay), I think every PI MD could do it.