Let's made a PC-base metal detector with usb interface !!!

[metsik]

wireless

Would you describe, what you want to do? The PC/laptop/netbook/tablet PC is the core of the processing part.
Which kind of data would you like to transfer?
Which radio module are you referring to?

The ASK (amplitude shift keying) is a digital modulation type. Most of the available radio modules aren't suitable for this job.
Aziz

I want to cut the middle of the USB wire.
In one side to put a transmitter, and in the other to put a receiver.
I have a set of one transmitter, and one receiver, using ASK.

the data is visual (web camera)

I am processing my data with a laptop.

I Know how to receive and process it on my laptop.
the only problem is that I dont know how can I combine between the two.

Matar Maoz

[Aziz]

I want to cut the middle of the USB wire.
In one side to put a transmitter, and in the other to put a receiver.
I have a set of one transmitter, and one receiver, using ASK.

the data is visual (web camera)

I am processing my data with a laptop.

I Know how to receive and process it on my laptop.
the only problem is that I dont know how can I combine between the two.

Matar Maoz

Hi Matar Maoz,

I am sorry, but I can't help you. You are trying to use a complete different application.
Just look in the internet. Maybe there is someone, who can help you.

Aziz

[Aziz]

Hi Matar Maoz,

maybe you need such a configuration:
http://www.dlink.com/products/?pid=629

But I don't know, whether it will work.

Aziz

[cko47]

Sound card

Hi,
Thanks for ms.nomi and gwzd ...
yes, PDA can be better in light weight, but did PDA cpu enough for this job?

also programming of pda is which language? what is usb interface for PDA?
if you have any idea please share it to use for our purpose...

anyway,for laptop i found a usb interface with PIC18F4550 to start:
i am waiting for any idea, thanks...

I have created the program which displays an entrance signal from a sound card. The unfinished version is placed in the bottom of my message. I used the sound card. It has poor qualities therefore displayed signal in the program of distortion. But with the help of this program it is possible to simulate work of the detector. While the not complete version is placed bellow.
If to use a sound card of higher quality that of distortion should decrease. Sample rate must be > 96000 (96Khz or more), etc 192 Khz.

At connection of a signal it is necessary to reduce by an input sound card a signal up to 0,5 volts using of a divider. Differently sound card can burn (crashed) .
My PC
CPU 1.6 GHz
OS Windows XP
Sound card Realtek AC97 Audio
Lin input

[WM6]

I have created the program which displays an entrance signal from a sound card. The unfinished version is placed in the bottom of my message. I used the sound card. It has poor qualities therefore displayed signal in the program of distortion. But with the help of this program it is possible to simulate work of the detector. While the not complete version is placed bellow.
If to use a sound card of higher quality that of distortion should decrease. Sample rate must be > 96000 (96Khz or more), etc 192 Khz.

At connection of a signal it is necessary to reduce by an input sound card a signal up to 0,5 volts using of a divider. Differently sound card can burn (crashed) .
My PC
CPU 1.6 GHz
OS Windows XP
Sound card Realtek AC97 Audio
Lin input

Great work cko47.
Congratulation and thank you.

[cko47]

Great work cko47.
Congratulation and thank you.

I replace the attachment It had some errors.
How I can edit my message for changing attachment new version?. Excuse me for my bad English.
Thank You for your opinion.

[WM6]

I replace the attachment It had some errors.
How I can edit my message for changing attachment new version?. Excuse me for my bad English.
Thank You for your opinion.

Editing possibilities of posts are limited in time. After EDIT button near to your post dissapear you cannot edit your post anymore, but you can stil ask admin (Qiaozhi) to make some changes for you (as attachement replacement par example).

[Qiaozhi]

I replace the attachment It had some errors.
How I can edit my message for changing attachment new version?. Excuse me for my bad English.
Thank You for your opinion.

There is a time limit, but (as you've now posted an updated version) I will leave the original to maintain continuity.

[Aziz]

I replace the attachment It had some errors.
How I can edit my message for changing attachment new version?. Excuse me for my bad English.
Thank You for your opinion.

Hi cko47,

good to know, I am not the only one, who plays with sound cards.
Well done.

Aziz

[cko47]

There is a time limit, but (as you've now posted an updated version) I will leave the original to maintain continuity.

Thank You for your reply.
You can write to me using my email (it is in application - Pulse Induction Analyser as attachment). I placed modified version (but again incomplete) in reply for WM6. Please visit to reply for WM6.
Changes and corrections of the mentioned program I make of each day. While not receive yet ready product. I shall be grateful for a finding of errors.
Have a nice day.

[cko47]

Pulse Induction Analyser

There is a time limit, but (as you've now posted an updated version) I will leave the original to maintain continuity.

It is working version program but without complete Help and setting form. Problem with synchronization was resolved. Try this program with Hammer head PI MD. Connect to TP4 using R divider. Input signal must be less than 0.5 v.

Have a nice day

[cko47]

Sound card for simulation of HH PI MD. Program

[quote=vistac2000;70303]Hi friends,
I almost new in http://thunting.com/geotech/forum, and see this site amazing and very interest about metal detectors,
at first I am sorry if my english is not very good ...

I wish with your helping, we can made a new PC-based metal detector with usb interface, this metal detector will can operate with pc or laptop very well and with some nice advantages, such as exact discrimination & even measure depth of target ! and others ...



I resolve synchronization problem in my program - Pulse Induction Analyser. It is working. But without complete Help and Settings form. You can try use this program with HH project.

[miki73]

ib-pi coil

Can sombody explain me bether whot is magnet wire?
I can see we have bether caracteristic with ib-pi coil.
How can measure balance in this coil?
Measure voltage on output of rx diferent amplifier, controling current on bucking coil and try to
pick up minimum voltage on rx??
Azziz please thell me how you measure noise on some stage.With your scope or you calculate
this.Can i use usb digital scope to see noise..

Sorry for maybe my stupid question..

Regards!

[Aziz]

Can sombody explain me bether whot is magnet wire?
I can see we have bether caracteristic with ib-pi coil.
How can measure balance in this coil?
Measure voltage on output of rx diferent amplifier, controling current on bucking coil and try to
pick up minimum voltage on rx??
Azziz please thell me how you measure noise on some stage.With your scope or you calculate
this.Can i use usb digital scope to see noise..

Sorry for maybe my stupid question..

Regards!

Hi Miki73,

Magnet wire is enamelled copper wire. It has a very thin insulation and is usually used in coils, transformators or electric magnets (-> magnet wire). PI coils should use a different wire (with thicker low dielectric insulation, like PP or teflon, ..) to lower the interwire capacitance of the coil. VLF coils can be wound with magnet wire, as there is usually a resonant capacitor connected to the coil and the interwire-capacitance is not so dominant.

Induction balance is best achieved with two D shape coils (DD coil) by overlapping transmit (TX) and receive (RX) coil. The voltage induced in the RX coil should be as low as possible not to overload the input amplifier. The induction balance is achieved manually by setting one of the coils at a specified overlapped position (usually small overlapping area).

Induction balance by adjusting the bucking coil:
This coil type is usually a concentric co-planar coil with the main TX coil outside and the bucking coil inside (often half diameter). The bucking coil is wound in reverse direction referred to the TX coil but is connected in series with the TX coil. It has a specified number of turns to make a rough induction balance. The RX coil is often at the same diameter as the bucking coil with some distance gap to the bucking coil. Fine induction balance can be achieved by varying the distance gap to the bucking coil. This coil type is not for beginners and is quite difficult to make (to balance).
Make the DD coil. It's much easier.

Noise measurement (not for beginners):
I am using my sound card and a FFT software (spectrum analyser software) to measure the noise floor directly in decibel (dB). It is possible to see, how much noise is at a specific frequency (frequency-domain view). There are many software tools, which makes measurements and calculations easy (look in the internet).

You can use oscilloscope or usb scope as well to see the noise in time-domain view. However, it is difficult to measure the noise at a specified frequency.

One have to distinguish between the noise spectrum density (referred to bandwidth 1 Hz and specified for each frequency) and root mean square (RMS) for a specified bandwidth (for instance 0 Hz .. 10 kHz).
Have a look at the following site for further info:
http://www.ecircuitcenter.com/Circuits/Noise/Noise_Analysis/res_noise.htm
And the great internet (lot's of useful informations there).

Cheers,
Aziz

[Aziz]

Thanks

Hi all,

thanks for Geotech staff, mikebg and other friends for congratulating and remembering my birthday. I did forget it due to lots of work. I am getting really old (Alzheimer).

During the last weeks, I have made lots of iron oxide/hydroxide. I have corroded 1.2 kg of fine steel wool for further mineral ground tests (type 00 and 0, 000 is the expensive but most fine mesh type, which I didn't use). It gives a good mixture of different iron oxides/minerals with some content of magnetic property too. The fine mesh steel wool corrodes quite fast after removing its oil film. I have sprayed it every day with water with a breeze of salt solved in it. It takes appoximately 3-4 weeks.

I also have started a new PI controller hardware, which I hope makes everything simpler and cheaper. I am trying to reduce the number of sound cards for the application (from two into one). The objective is to use the internal sound card of the laptop and let the software synchronize to the PI controller. The PI controller will use a crystal controlled timer and the PC will get the timing information as well on the other channel. So external synchronisation of the PI controller is not necessary and the output channel of the sound card can be used for beeping. Note, this will save further battery power (no external sound card).

The new PI controller is quite trivial, simple and flexible for different coil configurations too (mono, IB, anti-interference, two-box). Only minor changes will be required (mostly on front-end amplifier and transmitter stage). I am getting really sick of making a new platform every time.

I hope, I can find an elegant and simple solution for the very accurate synchronisation without loosing much signal response spectral energy. The theory states, that it is possible. Well, I will see it.

Cheers,

Aziz