VLF MD with digital signal processing : Bee-Buzz 1

[Marchel]

Oh I finally figured out what the problem is with pm!
If I click on "Inbox" your message is not there, it simply does not exist.
But if I click on the above "Message Center" then your second message appears!??
Does this defy logic?

It's weird, if I want to ask you anything in the future I'll send you an e-mail instead

[ivconic]

It's weird, if I want to ask you anything in the future I'll send you an e-mail instead

[Atul Asthana]

Here is the complete project for Keil ARM and the file for displaying data in the MCUViewer program, which is in the Media folder.

https://www.mediafire.com/file/qbp8x...ector.zip/file

https://github.com/klonyyy/MCUViewer

great,


thank you. I will talk to my favorite programmers to experiment, though they seem to be more comfortable with stm32mx cube.

[Atul Asthana]

I plan to dedicate more time on researching to further improve this metal detector, aiming to maximize the utilisation of microcontroller's processing power to create a distinctive and slightly better device, better than a standard, run-of-the-mill one.

Despite the limitations of using the internal 12-bit ADC, I believe it's possible to reduce the noise floor, enhance the effective number of bits (ENOB), improve target identification precision, and reduce power consumption, and all this at a very low cost.

[Atul Asthana]

I'd have much preferred many more experts joining in to share their knowledge and expertise to improve this md further.

my knowledge (and not the expertise) is limited to 30-40 years old signal processing and I guess, a lot of newer knowledge exists that can improve this design.

[Atul Asthana]

For this detector, I have set the lpf corner frequency of 1 Hz for ambient response and 100 Hz for target response.

What are the typical values used by commercial detectors?

Should I implement a selectable range, or allow a continuous selection from, for example, 1 Hz to 0.1 Hz, enabling users to choose a value that best suits their needs?

[Marchel]

I have been into metal detectors for a long time, but I am self-taught in programming and I am still learning. It would be great if a VLF digital metal detector with direct sampling was designed that would be fully functional and available to everyone. There are people on this forum who have built their own fully functional metal detectors, but they keep their secrets to themselves, it would be great if people who have already built a functional metal detector joined.

[Marchel]

I think that even a metal detector with an internal ADC can work well, the Mole metal detector is proof of that.

http://www.radiodom.org/index/krot_stm/0-32

[Marchel]

great,


thank you. I will talk to my favorite programmers to experiment, though they seem to be more comfortable with stm32mx cube.

I use MCUViewer for debugging because it has better graphics and better features, but that's probably just my opinion.

[Atul Asthana]

I have been into metal detectors for a long time, but I am self-taught in programming and I am still learning. It would be great if a VLF digital metal detector with direct sampling was designed that would be fully functional and available to everyone. There are people on this forum who have built their own fully functional metal detectors, but they keep their secrets to themselves, it would be great if people who have already built a functional metal detector joined.

Are there any professionals employed by commercial metal detector manufacturers on this forum?

It would be incredibly valuable to hear their insights. My knowledge of metal detectors is quite limited and primarily drawn from older sonar and navigation radar technologies, dating back 30-40 years.

Any expertise or information shared would be greatly appreciated.


and, does this design violate any patents in any country, though it should not be, being 30-40 years old.

or can I learn from any expired patents?

[Atul Asthana]

I think that even a metal detector with an internal ADC can work well, the Mole metal detector is proof of that.

http://www.radiodom.org/index/krot_stm/0-32

its not the adc/ics, its the process : signal processing, user interaction, adaptability and the over all functionality of the device.

if the process reasonably corelates to the requitements, any other sufficiently powerful processor, even with an external audio codec will do the job very well.

my objetive is to first get the processes in shape, and then implement.
later, we could look at esp32 (which seems much more capable, sans its adc, which can be substituted by an external codec) would make a better / more capable md, where even kalman filters etc can be implemented for noise management.

[Atul Asthana]

Based on my discussions with several embedded system designers and leaders from commercial embedded companies regarding the use of the ESP32 and a 24-bit codec, I would appreciate it if experts could analyze and share their opinions on this topic:

Upgrading to an ESP32 and a 24-bit codec offers potential benefits like increased processing power and higher resolution, but these may not always translate to significant real-world improvements in a metal detector. The ESP32 allows for more complex algorithms (e.g., filtering, frequency domain analysis), while a 24-bit codec reduces quantization noise and increases dynamic range.

However, the limiting factor in most metal detector/similar designs is often not the microcontroller or ADC resolution, but rather analog noise (thermal, EMI) and ground effects. Optimizing the analog front-end (low-noise op-amps, shielding, PCB layout) and implementing effective signal processing techniques are far more crucial.

A well-designed STM32-based system with its internal 12-bit ADC, using the optimized techniques, can achieve exceptional performance, far surpassing traditional analog VLF metal detectors. This is because digital signal processing allows for precise control, noise reduction, and advanced target identification that are simply not possible with purely analog circuitry. Therefore, focusing on software optimization and careful analog design is the most effective approach for achieving high performance.

[Atul Asthana]

I have been into metal detectors for a long time, but I am self-taught in programming and I am still learning. It would be great if a VLF digital metal detector with direct sampling was designed that would be fully functional and available to everyone. There are people on this forum who have built their own fully functional metal detectors, but they keep their secrets to themselves, it would be great if people who have already built a functional metal detector joined.

we will try and build a fully functional direct sampling vlf md, after we've done some research into most of the aspects, inclufing complexity of the software and of writing the code.

those, who have made their own, are not bound to share their designs (the sofware and hardware), but could share design philosophy / processes, giving us insights into the working principles or techniques and other aspects.

so lets work on with whatever knowledge we have or we can gather, and create some thing simple and useful.

[Marchel]

My detector design works with the XP Deus X35 coil so the TX signal is rectangular, and what TX signal do you want to work with ?.

[Carl-NC]

Are there any professionals employed by commercial metal detector manufacturers on this forum?

Yes, I work for FTP (Bounty Hunter, Teknetics, Fisher).

its not the adc/ics, its the process : signal processing, user interaction, adaptability and the over all functionality of the device.

It is both. You can't get high performance results with low performance hardware, no amount of software can fix a bad ADC. However, it is often a useful step to start out with lower ambitions and simpler hardware and work your way up. For a 'why' see my next comment.

my objetive is to first get the processes in shape, and then implement.

You can talk about the process for months on end, but the most valuable step is to build a circuit and get it working. For that, all you need is a TX driver, preamp, micro, and coil. Build it, make it work! You'll learn a whole lot more from that than continuing to talk about it. This thread is now 11 pages long and your very first post was a reasonable plan of what you should do.