What is really going on inside our detectors??

uhfradarwill

Full Member
Mar 20, 2022
115
458
Barre, MA
Detector(s) used
Minelab:
Sovereign GT
Equinox

Tesoro:
Comparde
After many years in the weak signal Radio Frequency state of the art world, especially radar for Ionospheric research, my guess is that most modern detectors are using a software designed radio hardware platform.
It wouldn't be hard to use these transceivers to transmit and receive signals from ~4 Khz to over 40 Khz and measure phase differences.

I think a coil is mostly just a coil, tried and true.

It's the software that greatly defines a detector's performance.

Just a guess, but if I had to assemble a team to design a kick ass unit, I'd go the SDR route and get some awesome software people to understand the problem and write kick ass code!!
Happy hunting....
 

crashbandicoot

Gold Member
Sep 27, 2020
9,373
17,402
Dumas,AR
Primary Interest:
All Treasure Hunting
After many years in the weak signal Radio Frequency state of the art world, especially radar for Ionospheric research, my guess is that most modern detectors are using a software designed radio hardware platform.
It wouldn't be hard to use these transceivers to transmit and receive signals from ~4 Khz to over 40 Khz and measure phase differences.

I think a coil is mostly just a coil, tried and true.

It's the software that greatly defines a detector's performance.

Just a guess, but if I had to assemble a team to design a kick ass unit, I'd go the SDR route and get some awesome software people to understand the problem and write kick ass code!!
Happy hunting....
Sounds like a plan!
 

alloy_II

Sr. Member
Dec 24, 2021
462
854
Radar for Ionospheric research, sounds fascinating, way above my pay grade.

I totally agree there's nothing magical about the coil, using the DD as an example the 6 inch coil, most likely has the same length of wire as the 12 inch coil. Just wound into a smaller space.

One give away with the Nox series, the early release at the time of sale did not have 4 khz installed so this tells me the frequnceys are synthesized..

Frequency synthesizer.

The limitations would be with the antenna which is tuned to work within this ~4 Khz to over 40 Khz range of frequencies.

An OHM measurement would verify if each of different sized coils offered use the same length of wire.

VA7ELM signing off.
 
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alloy_II

Sr. Member
Dec 24, 2021
462
854
Off topic, in this video the radio frequency waves to break the oxygen/hydrogen bonds of water turning it into fuel.

BURNING SALT WATER AS FUEL BY FREQUENCY

 
Last edited:

alloy_II

Sr. Member
Dec 24, 2021
462
854
After many years in the weak signal Radio Frequency state of the art world, especially radar for Ionospheric research, my guess is that most modern detectors are using a software designed radio hardware platform.
It wouldn't be hard to use these transceivers to transmit and receive signals from ~4 Khz to over 40 Khz and measure phase differences.

I think a coil is mostly just a coil, tried and true.

It's the software that greatly defines a detector's performance.

Just a guess, but if I had to assemble a team to design a kick ass unit, I'd go the SDR route and get some awesome software people to understand the problem and write kick ass code!!
Happy hunting....
A bit of research revels that Minelab is using SDR technology.

Source.
Detector manufactured by Minelab Electronics Pty Ltd operating frequencies, user manual, drivers, wireless reports and more. FCC ID.io; Blog; Search; FCC ID Z4C-0041 ... Software Defined/Cognitive Radio.

Not sure which model of detector this FCC application was for.

Screenshot from 2022-05-03 11-04-12.png


Screenshot from 2022-05-03 11-06-33.png
 

alloy_II

Sr. Member
Dec 24, 2021
462
854
After many years in the weak signal Radio Frequency state of the art world, especially radar for Ionospheric research, my guess is that most modern detectors are using a software designed radio hardware platform.
It wouldn't be hard to use these transceivers to transmit and receive signals from ~4 Khz to over 40 Khz and measure phase differences.

I think a coil is mostly just a coil, tried and true.

It's the software that greatly defines a detector's performance.

Just a guess, but if I had to assemble a team to design a kick ass unit, I'd go the SDR route and get some awesome software people to understand the problem and write kick ass code!!
Happy hunting....
I did a browse about the article on SDR on the wikipedia page, mentioned a sound card was needed to pull this off.

I'm thinking all the necessary hardware required is already installed on mobile phones.

Smartphones are easy to root then install an alternative operating system.

So why not turn an old phone into a metal detector.

How to Root Your Android Device​

Source.

How to turn your Android phone into a metal detector​

Source.
 
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Treasure_Hunter

Administrator
Staff member
Jul 27, 2006
45,645
47,631
Florida
Detector(s) used
Minelab_Equinox_ 800 Minelab_CTX-3030 Minelab_Excal_1000 Minelab_Sovereign_GT Minelab_Safari Minelab_ETrac Whites_Beach_Hunter_ID Fisher_1235_X
Primary Interest:
All Treasure Hunting
Music video deleted, please do not post music videos in our Tech forum.
 

Carl-NC

Bronze Member
Mar 19, 2003
1,808
1,192
Oregon & Texas
Detector(s) used
Custom Designs and Prototypes
Primary Interest:
All Treasure Hunting
Just a guess, but if I had to assemble a team to design a kick ass unit, I'd go the SDR route and get some awesome software people to understand the problem and write kick ass code!!
I designed SDR chips for Analog Devices, now I design metal detectors. Metal detectors have already moved toward SDR equivalence, they newer models (X-Terra, Deus 1/2, Equinox, probably Legend) are all direct-sampling architectures so filtering, demodulation, and phase analysis are all done in software.
A bit of research revels that Minelab is using SDR technology.

Source.
Detector manufactured by Minelab Electronics Pty Ltd operating frequencies, user manual, drivers, wireless reports and more. FCC ID.io; Blog; Search; FCC ID Z4C-0041 ... Software Defined/Cognitive Radio.

Not sure which model of detector this FCC application was for.
That was likely for their Bluetooth headphones, metal detectors don't run that high. Minelab is also part of Codan which has a military radio division.
 
OP
uhfradarwill

uhfradarwill

Full Member
Mar 20, 2022
115
458
Barre, MA
Detector(s) used
Minelab:
Sovereign GT
Equinox

Tesoro:
Comparde
  • Thread Starter
  • Thread starter
  • #11
I designed SDR chips for Analog Devices, now I design metal detectors. Metal detectors have already moved toward SDR equivalence, they newer models (X-Terra, Deus 1/2, Equinox, probably Legend) are all direct-sampling architectures so filtering, demodulation, and phase analysis are all done in software.

That was likely for their Bluetooth headphones, metal detectors don't run that high. Minelab is also part of Codan which has a military radio division.
I knew it!! Thank for the info!!
 

99thpercentile

Jr. Member
Nov 2, 2006
95
26
Evergreen, CO
Detector(s) used
Geonics EM61-MK2, Geophex GEM-3, GapEOD UltraTEM III, Minelabs F3, Foerster MINEX 2FD 4.500
Primary Interest:
All Treasure Hunting
The most frustrating part about hobbyist and military metal detectors for me as a geophysicist is that they are still essentially analog output devices where the operator is listening for the whee-whee sound. In geophysics as applied to landmine, unexploded ordnance (UXO), and improvised explosive device (IED) detection all of our metal detectors for almost 25 years utilize the concept of digital geophysical mapping (DGM). An operator could be deaf and it wouldn't matter to us since the sensor output is saved along with the exact time and position of the measurement. Since selective availability (SA) was turned off for the global positioning system (GPS) in 2001, every survey done for any of the applications listed above utilized centimeter accurate satellite positioning. The idea of trying to find items in real time by the sound of the whee-whee seems ludicrous to me. I'm not sure how to bring the industry into the past, not the present, of geophysical instrumentation.

All of the metal detectors currently used for UXO detection fall under the advanced geophysical classification (AGC) banner. The instruments are time domain electromagnetic induction (TDEM) sensors with a sufficient number of time gates (~27+) to fully characterize the target decay curve. The receivers all have three orthogonal coils so that we can completely characterize the target response. A few of the systems have multiple orientation transmitter coils. With these systems we can detect 100% of the targets in the ground, discriminate 100% of the targets as UXO or non-UXO, and then classify 100% of the UXO targets by the exact model of UXO, depth to the target, and the orientation in three dimensions of the targets. I can't find a single hobbyist metal detector that will record all of the data at a reasonable rate (minimum 10 Hz, ideally 20 Hz) with a GPS position and time stamp. The Minelab CTX 3030 is the closest to a real geophysical instrument but it only saves the GPS log file and location of any marked targets, it doesn't save any of the data. I do have CEIA CMD CIED unit that saves the sensor output and GPS position, but only at 1 Hz.
 
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uhfradarwill

uhfradarwill

Full Member
Mar 20, 2022
115
458
Barre, MA
Detector(s) used
Minelab:
Sovereign GT
Equinox

Tesoro:
Comparde
  • Thread Starter
  • Thread starter
  • #13
The most frustrating part about hobbyist and military metal detectors for me as a geophysicist is that they are still essentially analog output devices where the operator is listening for the whee-whee sound. In geophysics as applied to landmine, unexploded ordnance (UXO), and improvised explosive device (IED) detection all of our metal detectors for almost 25 years utilize the concept of digital geophysical mapping (DGM). An operator could be deaf and it wouldn't matter to us since the sensor output is saved along with the exact time and position of the measurement. Since selective availability (SA) was turned off for the global positioning system (GPS) in 2001, every survey done for any of the applications listed above utilized centimeter accurate satellite positioning. The idea of trying to find items in real time by the sound of the whee-whee seems ludicrous to me. I'm not sure how to bring the industry into the past, not the present, of geophysical instrumentation.

All of the metal detectors currently used for UXO detection fall under the advanced geophysical classification (AGC) banner. The instruments are time domain electromagnetic induction (TDEM) sensors with a sufficient number of time gates (~27+) to fully characterize the target decay curve. The receivers all have three orthogonal coils so that we can completely characterize the target response. A few of the systems have multiple orientation transmitter coils. With these systems we can detect 100% of the targets in the ground, discriminate 100% of the targets as UXO or non-UXO, and then classify 100% of the UXO targets by the exact model of UXO, depth to the target, and the orientation in three dimensions of the targets. I can't find a single hobbyist metal detector that will record all of the data at a reasonable rate (minimum 10 Hz, ideally 20 Hz) with a GPS position and time stamp. The Minelab CTX 3030 is the closest to a real geophysical instrument but it only saves the GPS log file and location of any marked targets, it doesn't save any of the data. I do have CEIA CMD CIED unit that saves the sensor output and GPS position, but only at 1 Hz.
This is very interesting, thanks.
So I'll have to set-up my Trimble GNSS RTK system and carry the rover while I swing.
Now, all I have to do is interface it with my Equinox.

I think I'll just hunt in the all metal mode and hope for the best.

What ever happened with the pulse induction technology? Did it die because of it's lack of discrimination.

Don't even get me started on ground penetrating radar......
 

alloy_II

Sr. Member
Dec 24, 2021
462
854
This is very interesting, thanks.
So I'll have to set-up my Trimble GNSS RTK system and carry the rover while I swing.
Now, all I have to do is interface it with my Equinox.

I think I'll just hunt in the all metal mode and hope for the best.

What ever happened with the pulse induction technology? Did it die because of it's lack of discrimination.

Don't even get me started on ground penetrating radar......
I was suckered into believing the hype, years ago had purchased the Garret Infinium LS.

Not an ideal metal detector on the prairie farm land, then at 5.5 pounds the machine soon gets very heavy.

My daughter living in Penticton BC with several beaches is now the proud owner.

I now own an Equinox 800, IMO much better suited to my age group.
 

99thpercentile

Jr. Member
Nov 2, 2006
95
26
Evergreen, CO
Detector(s) used
Geonics EM61-MK2, Geophex GEM-3, GapEOD UltraTEM III, Minelabs F3, Foerster MINEX 2FD 4.500
Primary Interest:
All Treasure Hunting
This is very interesting, thanks.
So I'll have to set-up my Trimble GNSS RTK system and carry the rover while I swing.
Now, all I have to do is interface it with my Equinox.

I think I'll just hunt in the all metal mode and hope for the best.

What ever happened with the pulse induction technology? Did it die because of it's lack of discrimination.

Don't even get me started on ground penetrating radar......
You don't have to use an RTK GNSS receiver for your hobbyist projects. Many current archeological geophysical surveys still don't use RTK GNSS while surveying. They set out a system of grids, typically 20 to 30 m on a side, then they collect their data as a series of parallel lines in opposite directions. The data is then rubber sheeted to ensure that the start and end locations all match. The data can then be gridded and displayed. Ideally all hobbyist instruments would have a built in data logger as well as an inexpensive GNSS receiver for approximate locations and accurate timing.

I'm not sure what you mean about what happened to pulse induction technology? TDEM is the standard approach for actual geophysical surveys as it can provide the best discrimination.

I'm also not sure what you mean when you say don't get me started on GPR. I use GPR every day. I have used equipment from every legitimate manufacturer. I have owned GPR systems ranging from $15K up to $300K depending on the requirements. My PhD is about measuring the complex electromagnetic properties of materials such as soils so that I can predict how GPR will perform. GPR is very site dependent, but it is the highest resolution geophysical method, so when you go to a site where you know it will work nothing else will give you the same information. If your targets are all metal, then GPR would never be my primary method as good metal detectors are much better instruments for that application.
 
OP
uhfradarwill

uhfradarwill

Full Member
Mar 20, 2022
115
458
Barre, MA
Detector(s) used
Minelab:
Sovereign GT
Equinox

Tesoro:
Comparde
  • Thread Starter
  • Thread starter
  • #16
You don't have to use an RTK GNSS receiver for your hobbyist projects. Many current archeological geophysical surveys still don't use RTK GNSS while surveying. They set out a system of grids, typically 20 to 30 m on a side, then they collect their data as a series of parallel lines in opposite directions. The data is then rubber sheeted to ensure that the start and end locations all match. The data can then be gridded and displayed. Ideally all hobbyist instruments would have a built in data logger as well as an inexpensive GNSS receiver for approximate locations and accurate timing.

I'm not sure what you mean about what happened to pulse induction technology? TDEM is the standard approach for actual geophysical surveys as it can provide the best discrimination.

I'm also not sure what you mean when you say don't get me started on GPR. I use GPR every day. I have used equipment from every legitimate manufacturer. I have owned GPR systems ranging from $15K up to $300K depending on the requirements. My PhD is about measuring the complex electromagnetic properties of materials such as soils so that I can predict how GPR will perform. GPR is very site dependent, but it is the highest resolution geophysical method, so when you go to a site where you know it will work nothing else will give you the same information. If your targets are all metal, then GPR would never be my primary method as good metal detectors are much better instruments for that application.
I just don't see much hype about PI applied to hobby detecting anymore.

For a living I am involved in high power, 2.5MW, radars for Ionospheric research and in my spare time I'm building a homebrew SDR based GPR.

I'm no PhD but know enough to know what I don't know lol
Happy hunting....
 

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