Metal Detector written in Octave/Scilab?

[Atul Asthana]

Are there any metal detectors available on Scilab or Octave (or even Matlab)?
OR
Has any one tried writing a metal detector on any of the signal processing platforms available on PC (my preference is Linux)?
OR
Has any one written receive side signal processing part on any signal processing platform?

[Atul Asthana]

To use a laptop/Android tablet/phone as a metal detector

These devices have a mic input, speaker output, a large screen, multiple buttons and a lot of computing power.

A VLF should be very easy.

Other mods to VLF theme could also be implemented with relative ease.

The speaker output can be used to drive the tx coil (may be with a buffer or an audio amp), with any kind of waveform (a chirp??).

The mic input can take signal from the rx coil (again, may be with a good, low noise preamp).

The computing power can be used for running signal processing algorithms on the received signal, and for target identification.

As an example:
A chirp of a small duration can be sent and the received signal can be analysed using wavelet transform.

The tablet makes it possible to simultaneously run multiple signal processing algorithms and compute target's identification.

Also, since the metal detection part will primarily be software, the algorithms can be tweaked for the soil conditions and target type.

Any interests?

Its too much of a hassle for me to learn Scilab, I did my signal processing almost 30 years ago. I'd prefer if the younger lot can take over the technology development part.
Couple of college going kids may be able to do this, if guided properly.

Aziz, Carl, others in commercial design/production companies : any thing that can be done?

[Atul Asthana]

A smart phone based metal detector in production

There seems to be one such MD here which uses smartphone for processing. I don't know how or what it processes, but this seems to be the way forward.
http://www.okmmetaldetectors.com/pro...FcN66wodVyG7QQ

BTW, I am not connected to OKM or any of the people working there.

[joop]

This is not a metal-detector but a magnetometer. I think it must be using a fluxgate to measure changes in the earth magnetic field.

[moodz]

These devices have a mic input, speaker output, a large screen, multiple buttons and a lot of computing power.

A VLF should be very easy.

Other mods to VLF theme could also be implemented with relative ease.

The speaker output can be used to drive the tx coil (may be with a buffer or an audio amp), with any kind of waveform (a chirp??).

The mic input can take signal from the rx coil (again, may be with a good, low noise preamp).

The computing power can be used for running signal processing algorithms on the received signal, and for target identification.

As an example:
A chirp of a small duration can be sent and the received signal can be analysed using wavelet transform.

The tablet makes it possible to simultaneously run multiple signal processing algorithms and compute target's identification.

Also, since the metal detection part will primarily be software, the algorithms can be tweaked for the soil conditions and target type.

Any interests?

Its too much of a hassle for me to learn Scilab, I did my signal processing almost 30 years ago. I'd prefer if the younger lot can take over the technology development part.
Couple of college going kids may be able to do this, if guided properly.

Aziz, Carl, others in commercial design/production companies : any thing that can be done?

G'day .....the code that produces these nice sinc pulses was all done on linux in C using a sound card. Carl tried to claim that Whites had a patent on it but the White's patent is for a half sine pulse.

See this post and the rest of the thread ...

http://www.geotech1.com/forums/showp...10&postcount=8

I did not post the code ...I have noticed there are few people with coding skills on this board ...there are plenty who come up with good ideas ...and plenty who use them but dont contribute ... ( yeh OK its a rant )

moodz

[Atul Asthana]

Good ideas should be put to use

moodz,

I hope, I did not infringe any patents. If I did, it really doesn't matter since use of any kind of existing signal processing methodology (for tx and rx) is obvious and not novel. Though, there may be an inventive step involved in this.

I do not think that bipolar/unipolar pulse or chirp or any other kind of waveform on a metal detector would stand patentability examination.

Its very obvious for a person to use different tx waveforms and to use various signal processing techniques in rx.

Well, lets try and use the capability of a PC/Tablet/Smartphone to design a better metal detector.

And, I will not file a patent either;-)

moodz, it will be a good idea to write a metal detector on Scilab.

I'll request all those who can contribute, to join in.

[Atul Asthana]

This is not a metal-detector but a magnetometer. I think it must be using a fluxgate to measure changes in the earth magnetic field.

joop, thanks for pointing out that its a magnetometer.
I intended to refer to use of computing power of the smartphone for signal processing and visualisation.

[moodz]

moodz,

I hope, I did not infringe any patents. If I did, it really doesn't matter since use of any kind of existing signal processing methodology (for tx and rx) is obvious and not novel. Though, there may be an inventive step involved in this.

I do not think that bipolar/unipolar pulse or chirp or any other kind of waveform on a metal detector would stand patentability examination.

Its very obvious for a person to use different tx waveforms and to use various signal processing techniques in rx.

Well, lets try and use the capability of a PC/Tablet/Smartphone to design a better metal detector.

And, I will not file a patent either;-)

moodz, it will be a good idea to write a metal detector on Scilab.

I'll request all those who can contribute, to join in.

Thats a good idea Atul ... I am not interested in patents either .. I reckon those that indulge are enemies of mankind and progress of knowledge...however I digress ..in the open source software arena much more complex problems than metal detectors have been written ...you would have more success starting a project there ...here it is like a desert for software developers even the hardware is stuck in 555 land ... and apparently there are companies that will fire you if you design a circuit using a 555 ... LOL. Still maybe someone will come to your aid ... I would .... but I am too busy knocking out a next generation PI circuit at the moment.

BTW how is scilab going to get inside a smartphone ??

moodz

[Atul Asthana]

moodz, great that you are on to designing next gen PI MD. Wish you all the success.

Well, you are right on the 555 example. Most of the MDs rely on time domain processing, and signal processing in frequency domain has been barely used.

I guess, frequency domain processing will dramatically improve the functionality of metal detectors (PI and VLF/IB/------).

Smartphones (at present) may not be able to run Scilab, but tablets and laptops can, and Scilab code can be converted to C (http://forge.scilab.org/index.php/p/scilab2c/), which may be compiled and run on a smartphone.

[Tepco]

Carl tried to claim that Whites had a patent on it but the White's patent is for a half sine pulse.
moodz

Carl didn't tried to "claim" anything, Whites US 7649356, i suppose this is all about it. I just incidentally find this post and mentioned PDF, so, sorry, but i have to make few comments, especially on waveforms presented.

Waveforms are well known for many decades, also method to produce them. Technically, Zero Current Switching (ZCS) resonant 1/2f converter topology. At least few dozen patents use it. For all possible applications. Induction heating, welding, CCPS (capacitor charging PSU), X-ray power sources, lasers, particle accelerators and what not...Except MD machines. Since Fisher has patent on energy recovery pulse, ML on square wave, someone on tuned circuits etc, this is OK.

Well, almost. White,s can sue these guys, from Russia whit love, already done:
http://vash-ru.net/anker/a_pulse_2_opisanie.shtml
(Bipolar harmonic haversine?!? what a name!) Thing spew fire really, good detector.
(I'm not Russian, and i didn't designed that thing)

Now, few words about waveform, in technical, not lawyer's terms. Waveform is usually generated using half or full bridge MOSfet, or any other device whit reverse diode, IGBT or something. Coil inductance in this case (or transformer leakage L + some additional one if needed) and capacitor forms series resonant circuit at certain frequency. Drive frequency is exactly half of that, producing characteristic current and voltage waveforms presented in patent, timing can produce single, bipolar haversine, continuous waveform, and power devices switch on or off at zero current, reducing switching losses.

In PSU applications, (transformer instead of coil) this has tremendous advantage, high efficiency, and high core utilization, low EMI, making things smaller and cheaper. Generally, operation is either 50% duty cycle (full ZCS) or 12.5% or less (ZCS at turn on, non-ZCS at turn off), area between is "forbidden" due to high switch currents. Whit transformer, circuit acts as a constant current source from short ckt. to half of open ckt. voltage (usable up to 2/3), but can be regulated whit ext. feedback, many high power PSU units use this topology. Proving me as an ultimate source for completely useless OT information.

In MD use, this is highly efficient way to drive TX coil, only resistive and switching losses will dissipate energy, reactive part will remain in LC tank,no flyback loss , high drive currents are easy to achieve. Also sine, square or pulsed waveforms can do the same, but allready patented.

Then how will someone recover target information from this waveform, using sampling, sync detectors, ADC+MCU or DSP, vacuum tubes or whatever else,it is designer's choice.

Best regards, sorry for long and bit OT one.

[Aziz]

Are there any metal detectors available on Scilab or Octave (or even Matlab)?
OR
Has any one tried writing a metal detector on any of the signal processing platforms available on PC (my preference is Linux)?
OR
Has any one written receive side signal processing part on any signal processing platform?

Hi,

forget these tools. Just use a plain C/C++ code. There are many DSP source codes available in the internet. Pay attention to the functional separation of the functionality. Some tools offer a platform independent development environment. So you can port it easily into linux/windows/whateveryouwant...

Good luck.
Aziz

[moodz]

Carl didn't tried to "claim" anything, Whites US 7649356, i suppose this is all about it. I just incidentally find this post and mentioned PDF, so, sorry, but i have to make few comments, especially on waveforms presented.

Waveforms are well known for many decades, also method to produce them. Technically, Zero Current Switching (ZCS) resonant 1/2f converter topology. At least few dozen patents use it. For all possible applications. Induction heating, welding, CCPS (capacitor charging PSU), X-ray power sources, lasers, particle accelerators and what not...Except MD machines. Since Fisher has patent on energy recovery pulse, ML on square wave, someone on tuned circuits etc, this is OK.

Well, almost. White,s can sue these guys, from Russia whit love, already done:
http://vash-ru.net/anker/a_pulse_2_opisanie.shtml
(Bipolar harmonic haversine?!? what a name!) Thing spew fire really, good detector.
(I'm not Russian, and i didn't designed that thing)

Now, few words about waveform, in technical, not lawyer's terms. Waveform is usually generated using half or full bridge MOSfet, or any other device whit reverse diode, IGBT or something. Coil inductance in this case (or transformer leakage L + some additional one if needed) and capacitor forms series resonant circuit at certain frequency. Drive frequency is exactly half of that, producing characteristic current and voltage waveforms presented in patent, timing can produce single, bipolar haversine, continuous waveform, and power devices switch on or off at zero current, reducing switching losses.

In PSU applications, (transformer instead of coil) this has tremendous advantage, high efficiency, and high core utilization, low EMI, making things smaller and cheaper. Generally, operation is either 50% duty cycle (full ZCS) or 12.5% or less (ZCS at turn on, non-ZCS at turn off), area between is "forbidden" due to high switch currents. Whit transformer, circuit acts as a constant current source from short ckt. to half of open ckt. voltage (usable up to 2/3), but can be regulated whit ext. feedback, many high power PSU units use this topology. Proving me as an ultimate source for completely useless OT information.

In MD use, this is highly efficient way to drive TX coil, only resistive and switching losses will dissipate energy, reactive part will remain in LC tank,no flyback loss , high drive currents are easy to achieve. Also sine, square or pulsed waveforms can do the same, but allready patented.

Then how will someone recover target information from this waveform, using sampling, sync detectors, ADC+MCU or DSP, vacuum tubes or whatever else,it is designer's choice.

Best regards, sorry for long and bit OT one.

Dear Tepco if you read the complete thread you will see that Carl did imply ( claim ?? ) that Whites had a patent on this ...

See this post and the rest of the thread ...

http://www.geotech1.com/forums/showp...10

I agree with all your other commentary .... however in my opinion you are mistaking how the US patent system is used ... It does not matter if the waveforms or whatever are used in power supplies or space rockets if there is no patent covering metal detectors then you can apply for one. It is the application and means thereof of producing the waveform that is patented. Once the patent is granted it is a licence to sue anyone who utilses that application and means of generation (even if you use a different circuit .. they rarely publish an actual circuit in a patent ... only boxes ... which could be anything.) For companies like ML ... "all" their key intelletual property is basically waveform based .. there is nothing special about the circuits ... I mean how many ways can you connect a coil and a mosfet switch ?
moodz.

[Atul Asthana]

Hi,

forget these tools. Just use a plain C/C++ code. There are many DSP source codes available in the internet. Pay attention to the functional separation of the functionality. Some tools offer a platform independent development environment. So you can port it easily into linux/windows/whateveryouwant...

Good luck.
Aziz

Its will be far easier to do this in Scilab than in C.