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Newbie with first question - Rainer - 03-31-2022
Hi,
Just found this absolutely awesome APP and played with it a bit.
I am a retired 69 year old Textile Engineer making some experiments with magnetism eg Helmholtz coil, magnetometer, Hall sensors, etc.
My question is
Is there a way to Zero the magnetometer so I can measure the real µT inside my Helmholtz coil ?
Thanks in advance and regards
Rainer
RE: Newbie with first question - Jens Noriʇzsɔɥ - 04-03-2022
Technically, this should be possible: https://phyphox.org/wiki/index.php/Phyphox_file_format allows for quite some flexiblity and it looks like a simple button for storing the current value could do. At the end it would be the same as exporting the data to .xls or .csv and subtract a constant value in the data.
A fixed offset correction comes with some difficulties: the smartphone needs to be kept in exactly the same position all the time. Smartphones with a gyroscope can rather precisely determine an absolute position, see https://phyphox.org/wiki/index.php/Attitude_sensor, however, eliminating tilt might require some … maths.
Anyway, you should switch to the “raw magnetometer” in the “⋮” menu so that there are no calibration effects (there are lots of currents inside a smartphone so that the OS continuously recalibrates).
RE: Newbie with first question - Rainer - 04-03-2022
(04-03-2022, 04:33 PM)Jens Noritzsch Wrote: Technically, this should be possible: https://phyphox.org/wiki/index.php/Phyphox_file_format allows for quite some flexiblity and it looks like a simple button for storing the current value could do. At the end it would be the same as exporting the data to .xls or .csv and subtract a constant value in the data.
A fixed offset correction comes with some difficulties: the smartphone needs to be kept in exactly the same position all the time. Smartphones with a gyroscope can rather precisely determine an absolute position, see https://phyphox.org/wiki/index.php/Attitude_sensor, however, eliminating tilt might require some … maths.
Anyway, you should switch to the “raw magnetometer” in the “⋮” menu so that there are no calibration effects (there are lots of currents inside a smartphone so that the OS continuously recalibrates).
Hallo Jens,
Danke, This is a bit to high for me. There is one App for Android phone where I can just push a button and it sets the value to zero of course with certain jumps in the range of 0.0 to 0.3 µT and this is quite good as I can see the µTesla i am producing with my Helmholtz coil. OK, not research grade but good enough for me.
As the phone is laying in the Coil on a table without any movement this is already an advantage. I am not moving the phone inside the coil.
Grüße Rainer