Gradiometer query - Speake SCL007

[Jan]

Re: Fluxgate mag

Expect that when I move sensors far apart sensitivity will improve ?


As towed array, sensors say 2-3 meters apart will not be a big problem.... I think..


Regards, Jan

[Jan]

Re: Fluxgate mag

Expect that when I move sensors far apart sensitivity will improve ?


As towed array, sensors say 2-3 meters apart will not be a big problem.... I think..


Regards, Jan

[Jan]

Re: Fluxgate mag

Expect that when I move sensors far apart sensitivity will improve ?


As towed array, sensors say 2-3 meters apart will not be a big problem.... I think..


Regards, Jan

[Carl]

Re: Fluxgate mag

[Carl]

Re: Fluxgate mag

[Carl]

Re: Fluxgate mag

[Carl]

Re: Re: Question 4 the Group

Thanks, these were two packages I was looking at. Sounds like I can eliminate one.


- Carl

[Carl]

Re: Re: Question 4 the Group

Thanks, these were two packages I was looking at. Sounds like I can eliminate one.


- Carl

[Carl]

Re: Re: Question 4 the Group

Thanks, these were two packages I was looking at. Sounds like I can eliminate one.


- Carl

[fred]

Gradiometer query - Speake SCL007

I am trying to constuct an FGM gradiometer using Speake SCL007 FGM's.

I have a sine wave output from the differential, but it flatlines for a range of values.

Does anyone have any ideas about the feedback pin or whether calibration is necessary for a gradiometer?

Thanks,
Fred

[nickf]

Re: Gradiometer query - Speake SCL007

Just to be clear are you making a gradiometer using the SCL007 custom chip or doing something else ? (the actual sensors are called FGM-3s). I think the SCL007 is a specially programmed PIC (the pinouts are the same), Speake and co give details of the way it calibrates the two sensors in their documentation. I don't know the relationship between the digital output of the chip and the size of the magnetic anomaly though - you could try emailing them, they've been very helpful answering my questions.

The feedback pin is connected to one end of an internal coil which is wound around the sensor with the other end being grounded. I don't think its used with the SCL007 chip though.

Nick

[fred]

Re: Gradiometer query - Speake SCL007

We gave up on the feedback pin and wound our own coil around the sensor to create an offset. Thanks for your help though.

Incidentally, the change in frequency was about 3 times more than we were expecting...haven't worked out why yet.

Fred

[nickf]

Re: Gradiometer query - Speake SCL007

no worries ! you mentioned a sine wave differential in your first post, are you using your coil to equalise the sensor frequencies and then looking for beats ? I'm doing a few tests on my sensors at the moment to work out the best way to use them.