FPGA based UNIPI system

[Repwoc]

I know how you think in Britain! I happened to watch a video of a man who moved to England, he said that every year, whenever someone from the company goes on vacation, he brings something exclusive and something special from his country, it was the turn of that man from Serbia and he bought some black candies on with the name black odjacar, ordinary candies have a little spiciness but an unusual taste, everyone wondered why they were called black odjacar, as I understood from his story, they thought it was something like an insult to people with a different skin color. However, candies have nothing to do with that at all! It has nothing to do with valuation etc. those candies are a brand like Coca Cola, I hope you understand me?

I genuinely didn't understand what you meant by colored objects in the context of metal detecting, that's all. Now I do, so thanks for the explanation.

paul

[moodz]

...so I finished building a pergola in the backyard and now back to the project. Been chasing improved sensitivity and even though there is no amp on the frontend and the TX is running off 4 volts we get over a meter detection on the copper and aluminium test squares and very good detection on the .05g gold nugget.
The primary channel detects conductive objects and cancels ferrites ( and hopefully ground signal ) and once that was sorted it only took a copy and paste to implement the 2nd Disc channel which can resolve ferrous / non ferrous objects surprisingly well .... I thought I would have to put a alot more work into it but there you have it.

I will have to change the name of the detector from UNIPI as it is not a PI detector ... the TX is Sine wave basically single frequency 19 Khz.
Anyway here is a video of showing the target response of the 2nd Channel.


https://youtube.com/shorts/GYUeE3TZR...ZyewTACbMyVTBv

[moodz]

This is a test of full depth discrimination .. the most important test for a PI REPlacement. I just found the project name PIPER ( PI replacement project ) LOL
This project is now exceeding any PI detector I have used ( including commercial ). Noting of course this is all in the lab.
Cant test in the field yet till I sort out the user interface and put it all in a box.

Heres a video of disc at full depth ( in air )

https://youtube.com/shorts/P56z6dgOg...mKm4mRyJa3wuyG

[moodz]

... making up a field test unit. Spun the ADC board around on the FPGA board ( will have to remap the pins in code ).
ESP32 for house keeping WIFI / bluetooth etc.
TX board and power supply + hardware to be fitted.

[Mdtoday]

... making up a field test unit. Spun the ADC board around on the FPGA board ( will have to remap the pins in code ).
ESP32 for house keeping WIFI / bluetooth etc.
TX board and power supply + hardware to be fitted.

Look good Moodz.

cheers for posting progress

[moodz]

Look good Moodz.

cheers for posting progress

Thanks Brian ... I am moving closer to using your display unit.

[IBGold]

Hi Paul,

Have you stopped development work on the Magpie V3 if so I will pack it all away back on deck here again if you want the Board back let me know will send t to you will wait and see how this project goes best of luck and hi Brian.

Regards, Ian.

[moodz]

Hi Paul,

Have you stopped development work on the Magpie V3 if so I will pack it all away back on deck here again if you want the Board back let me know will send t to you will wait and see how this project goes best of luck and hi Brian.

Regards, Ian.

Thanks Ian ..Well ... this project has surpassed the V3 several times over. I was trying to do get the V3 to do what this project does however I have found for instance you need absolutely zero drift in the integrators for the method I am using and that will never happen in the analog world where the frontend of V3 lives. Keep the board .. I have enough already but thanks for trying it out. If I can get this curren project to finished stage I will send you one to test... dont hold your breath though LOL.
Cheers

[Mdtoday]

Hi Paul,

Have you stopped development work on the Magpie V3 if so I will pack it all away back on deck here again if you want the Board back let me know will send t to you will wait and see how this project goes best of luck and hi Brian.

Regards, Ian.

Hi Ian, hope you are doing well mate.

Cheers

[Olly]

Moodz you've inspired me to have another go at an FPGA based system.
I've got the same ADC development board you're using and am lucky enough to have a Kintex-7 FPGA board kicking around as well.
This has an HDMI connector on it so I've managed to get 720p (1280 x 720 x 60Hz) video working in order to display results as you do.
I noticed that you have a nice little font set at the bottom of your display, may I ask where you got that from or was it self developed?

Cheers
Olly

[moodz]

Hi Olly ... I used the yavga package from opencores.org ..but that site seems to be unmaintained these days so try here ..
https://github.com/freecores/yavga

The char maps are in there and it's open source.

[Olly]

Thanks Moodz, much appreciated!

[boilcoil]

... now trying to see if I can get some phase information out of the coil.

Hi Moodz,
You can try by two samples of the induction-balanced coil through on-time.
The first should be at an earlier stage (the linear part of growth), and the second in the exponential/halfsin part.
The two samples should behave in a slightly different way.
With ferrotarget, they will have the same trend, but different changes.
For highly conductive targets, they will have the same trend (opposite to the previous one), but different changes (opposite to the previous changes).
With resistive nonferro targets or very small ferro targets, they will have completely different trends.
By their different positioning, you can find the optimal response.
It's a bit like the phase shift in the VLF.

Try it, you don't lose anything.

Regards

[moodz]

Hi Moodz,
You can try by two samples of the induction-balanced coil through on-time.
The first should be at an earlier stage (the linear part of growth), and the second in the exponential/halfsin part.
The two samples should behave in a slightly different way.
With ferrotarget, they will have the same trend, but different changes.
For highly conductive targets, they will have the same trend (opposite to the previous one), but different changes (opposite to the previous changes).
With resistive nonferro targets or very small ferro targets, they will have completely different trends.
By their different positioning, you can find the optimal response.
It's a bit like the phase shift in the VLF.

Try it, you don't lose anything.

Regards

Hey thanks for the tip.

[moodz]

I have built up a compact version of the new POC ( proof of concept ) ready for some field trials.
It now fits into a case and runs of a lithium battery pack. The sensitivity is higher than the original and the TX efficiency is improved ( about 250 ma @ 5 volts = 2.2 amps peak to peak in the coil )

The classic test is the coke can test at 1 meter. This is in air and in the "noisy" lab environment ...
Its a BS test but it does have some merit in sensitivity estimation.

Here is the video.

https://youtu.be/tkT9uPBlLfY?si=yu3eOwthVYbhuisu