FPGA based UNIPI system

[moodz]

....were crackin out winners here like a battery shop at a racecourse !

Version 1.0 FPGA code completed .. whew.

Checkout the response to the jeweller's screwdriver in the video below

https://www.youtube.com/watch?v=K9_DWF0GUvA

moodz

[moodz]

.... yep the ripple in the integrator output was solar inverter magnetics ...
Flat as a pancake now.

[moodz]

UNIPI detects .05 gram nugget.

This is a good result as there are quite a few PI machines that cannot detect this particular test nugget at all.
Its even more spectactular when you consider the UNIPI has no preamp at all though there is headroom at the frontend ADC for approx 50x to 100x gain.

I would expect that a smaller coil would improve things also .. and maybe a OO coil or similiar for VLF. ( or maybe not )

below is the test on video ...

https://youtu.be/bLjRquZhnOY?si=AsKBNxSC98XQE8mz

[Mdtoday]

UNIPI detects .05 gram nugget.

This is a good result as there are quite a few PI machines that cannot detect this particular test nugget at all.
Its even more spectactular when you consider the UNIPI has no preamp at all though there is headroom at the frontend ADC for approx 50x to 100x gain.

I would expect that a smaller coil would improve things also .. and maybe a OO coil or similiar for VLF. ( or maybe not )

below is the test on video ...

https://youtu.be/bLjRquZhnOY?si=AsKBNxSC98XQE8mz

Great work Moodz, detecting that piece of gold, nice.
I would think that even a 5-10x gain ADC preamp would yield very acceptable returns without jeopardising the brilliant response you have currently.
Perhaps a preamp would also be a measure of protection for the ADC inputs too.
Nice work!

btw…that jeweller’s screwdriver from your previous video might have a brass handle. I have a similar set and the knurled handle is brass sleeve. The steel shank goes all the way through on the set I have.

cheers

[moodz]

Thanks mate ! I am aware that the hardware ( fpga chip and ADC ) are close to obsolete ... though you can still get them. I need to consider moving the code to an updated platform ( ie current FPGA and ADC ) before going to far.
We do need at least 24 bits of resolution ( not sure if it has to be 2.5 MSPS )... by the time I get the processing to the end of the chain I am using a 36 bit word in the integrator and the integrator values on the VGA display are bits 0 to 9 ( ie the lowest 9 bits ) of the 36 bit word so the noise is very low. I think I am using a novel algorithm in the VHDL which should be fully portable to new FPGA chips or even CPU and you cant patent VHDL code AFAIK.

Currently the chip is a XILINX Spartan 3A and the utilisation is low ... theres enough room there for a soft processor on chip.

Below are the compile results for the FPGA...

[Altra]

Great progress Moodz.
The screwdriver response is normal for IB coils, PI and VLF. Any elongated ferrous will react this way. Carl may have an explanation for the phenomenon? Crown bottle caps also present different responses depending on the angle.

[moodz]

Great progress Moodz.
The screwdriver response is normal for IB coils, PI and VLF. Any elongated ferrous will react this way. Carl may have an explanation for the phenomenon? Crown bottle caps also present different responses depending on the angle.

Thanks Altra .. yeh I am more used to mono - coils.... now trying to see if I can get some phase information out of the coil.

[Carl-NC]

How is it detecting the ferrite but not the hot rock?

[moodz]

How is it detecting the ferrite but not the hot rock?

good question ! .... I have a theory that some responding targets ( such as this hot rock - responds to PI and GPZ detectors ) are a balance between metallic ( inductive ) and ferrous ( magnetic ) so for a detector that has a bipolar target response like this one then there will be no response as the ferrrous vs inductive is not unbalanced enough to cause a response.
I am currently adding an IQ demod to the code to see if there is any response that way.

[moodz]

... so I did some more code work and now the UNIPI can cancel ( ignore ? ) ferrite responses without reducing metallic sensitivity.
We are still operating on single frequency ... and this is something I have always wanted in a detector and now it appears to be a reality.

Unfortunately you may have to throw the theory books out the window ....

Here is a video of the latest version in operation .... I have applied the technique in code ... but it also be done in hardware ... could be a patent in it.

https://youtube.com/shorts/tub-kIWJS...Tgtdp8epJ_GjHC

[Altra]

Shattering the laws of physics everyday. How does the new code respond to ferrous?

[JoyJo]

This is a wonderful result! Congratulations to you! You are a genius, dear moodz !

[moodz]

This is a wonderful result! Congratulations to you! You are a genius, dear moodz !

Thankyou ... but unfortunately I am not a genius or I would have continued this project I started 10 years ago.

[moodz]

Shattering the laws of physics everyday. How does the new code respond to ferrous?

I am using straight up physics but from first principles ... If you mean like descrim ?
It seems to now reject ferrous and hotrocks ( which it did already ) but any conductive metal registers as a target ( the more conductive .. the stronger response )

[moodz]

How is it detecting the ferrite but not the hot rock?

So I investigated why the hotrocks were not being detected ... the sensitivity was certainly high enough as I was able to detect a .05 gram gold target but not a hotrock ??.
nitially I thought I may have had a target "hole" and it was centred over maybe a range of targets including hotrocks.
More testing and code tweaking ... revealed that the hot rocks were not being detected because the code was already partially working and trying to reject ferrite responses ( ie opposite to conductive ) and this partial ferrite rejection was resulting in non detection of hotrocks.Once this fact was known the code was adjusted to cancel the ferrite response entirely and understanding this now allows a simple switch function (eg CANCEL ON/OFF) ... not sure when you want to detect ferrites though.

The solution to this problem might also be the road to full metal descrim... but jury is still out on that one.

So thanks Carl ... your question sparked the solution to this problem and solved another.

moodz.