Magnetometer drift?

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carlosjackal
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Magnetometer drift?

Post by carlosjackal » Thu Nov 03, 2016 7:26 pm

Hi all I would be interested in what folks think of these readings. At the moment I'm getting a dip every day from 18:00 which peaks at 00:00 then dips again at 06:00. This seems to be a daily occurrence over the last three days.

I can't work out why it is so regular if it's temperature issues. Any ideas?

I have attached a screenshot.

Thanks Carl
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drift.JPG
drift.JPG (148.43 KiB) Viewed 1048 times

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Montana
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Re: Magnetometer drift?

Post by Montana » Fri Nov 04, 2016 7:57 am

Your central heating?

alexandra

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Re: Magnetometer drift?

Post by carlosjackal » Fri Nov 04, 2016 2:53 pm

Hi yes thought that maybe the case but the timings are out I also turned off the heat in that room. The readings last night exactly the same. I'm baffled as it can't be outside temperature even as its like clockwork no matter if it's warm or cold.

Thanks Carl

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Re: Magnetometer drift?

Post by Montana » Fri Nov 04, 2016 2:59 pm

I think Mike G eventually settled on it being the central heating but it was a delayed reaction. I think he eventually ended with it in an insulated flask. Ideally I think it should be in a large deep hole in the garden soil. I am sure the boys will know exactly what it is.
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carlosjackal
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Re: Magnetometer drift?

Post by carlosjackal » Fri Nov 04, 2016 4:09 pm

Thanks I hope so. I should give a basic run down of my setup.

The sensor is about a meter underground fed with outside phone cable which is buried a few inches for most of the run.

The bat detector is sitting on the desk perhaps it needs to be totally insulated? Any ideas welcomed.

Regards Carl

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Re: Magnetometer drift?

Post by Carbon60 » Fri Nov 04, 2016 5:31 pm

Hi Carl,

I would say it's most likely a temperature issue, although it's odd that it's 'like a clock' and you've changed the temperature in the room. Take a look at the latest tutorial which explains how I encased the bat detector in a thermos flask, inside a 'cool box' with a thermostatically controlled heater mat (as for a terrarium). This is what it takes to maintain temperature. I was surprised at how sensitive the system is to temperature changes. I'm sure that this can be nulled using a formula that relates temperature to the readout, but I never got around to doing this.

If it isn't temperature, then it could be some type of voltage issue. I assume that you're feeding the FGM and Bat detector with very steady voltages.

Stu.
Last edited by Carbon60 on Fri Nov 04, 2016 6:02 pm, edited 1 time in total.
Lunt LS60THa B1200 PTFT
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Re: Magnetometer drift?

Post by Carbon60 » Fri Nov 04, 2016 5:57 pm

Carl,

Some images that might help......

Deconstructed bat detector mounted on a wooden board
DSC_0130_2.JPG
DSC_0130_2.JPG (169.93 KiB) Viewed 1005 times
Detector housed in thermos flask
DSC_0129_2.JPG
DSC_0129_2.JPG (93.32 KiB) Viewed 1005 times
Thermostatically controlled heater mat
DSC_0128_2.JPG
DSC_0128_2.JPG (125.64 KiB) Viewed 1005 times
Cool box with thermostatic controller mounted and set (to 27 deg C)
DSC_0124_2.JPG
DSC_0124_2.JPG (85.3 KiB) Viewed 1005 times
All a bit of a faff, but it works and is needed to keep the detector at a reasonably steady temperature.

Voltage regulation is also critical, as I've mentioned. I feed both sensor and detector with stabilised voltages to avoid any drift.

Stu.
Lunt LS60THa B1200 PTFT
150mm H-alpha Solar telescope with Lunt35 mod
DMK41, Basler acA1920-155
NEQ6 Pro-mount
Fluxgate Magnetometers (1s and 150s Cadence)
More images at http://www.flickr.com/photos/solarcarbon60/

carlosjackal
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Re: Magnetometer drift?

Post by carlosjackal » Fri Nov 04, 2016 7:42 pm

Wow may need to upgrade! yes I have built the double regulated supply running off a regulated supply. The bat has no temperature control at all so maybe the culprit. Thanks for taking the time to help out.

Regards Carl

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