Gradiometer for archaeology

Projects General Guidance
1

Hi
I am new to the forum so hello.
I have looked at another post on this subject but there have been no posts for sometime.
The Gradiometer I want to build uses 2 Speake & Co fluxgate magnetometers aligned in a vertical configuration 500mm apart.
Now I need to say I know little to nothing about electronics as I gave up physics for biology at school 45years ago.
I am looking to connect, if possible, to an Arduino Uno which will form the brains of a data logger. I will then download the data to a computer.
In the original plans for the Gradiometer from 2003 the mags are first connected to a SCL007 chip made by Speake which produces a 8 bit digital output. However the author says he intends using a PIC16f877-20 microprocessor. He says this will monitor the sensor output frequencies separately and store the results to a non volatile serial memory.
First question is how to configure this set up to read the signals from the mags using an Arduino?

I have some data on FGM-3 mags.

Sensitivity.+- 50,000nT at 5v
Output wave. Pulse width modulated
Output period. 3-25us
Power. 5+- 0.5 Vdc, 13mA approx 65mW
4 terminal device. 1: FB, 2: GND, 3: OUT, 4: +5v
Operating temp range. 0-50c
Supply current. 12mA
Period swing. 120KHz to 50KHz

Now this means little to me so you see I need help?

Thanks

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2

You can certainly read at least one magnetometer PWM output with an Arduino, but making sense of the reading will require the user manual or datasheet. Post a link if you have one.

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3

3 to 25 us isn't a great range for the basic timing functions.
Time to go off piste.

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4

I wondered about the 3-25 usec, too, but the "period swing" , whatever that is, has a much larger range.

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5

Hi

I will look for a data sheet.

Found this info:

Speake & Co make the SCL007 chip that excepts the 2 signals from the FGM-3 mags and does the digital mixing for us. The output of the gradiometer chip is an 8-bit parallel word which corresponds to the mix frequency. A zero output means the sensors see the same field, a full-scale output means there is a large difference. The SCL007 also has a “sign” bit which can tell us which of the two sensors is detecting an increase in the magnetic field, making the total output a true offset binary 9-bit word.

Would this mean that the digital signal from the mags, once combined by the SCL007 chip, could be read by an Arduino. They do also say you could use a DACS to convert to an analog signal.

Does this make any sense?

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6

Hello everyone, I would like to present myself. I am Geraldo and I work at GEM Systems.

GEM Systems is the manufacturer of the well know Gradiometer Overhauser, model GSM-19GW. This instrument has the most accuracy and sensibility in the market for Archeology survey.
If you would like to have more information, would you please send me your email to geraldo.pinto@gemsys.ca.

Best Regards.

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