Q:
What can cause very large offset errors in the ADIS16405 magnetometer outputs?
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A:
One potential cause is through magnetizing internal materials. This happens when devices experience high-intensity magnetic fields, typically in excess of 20 Gauss. Fortunately, these units can be "de-magnetized" using relatively simple equipment. The following videos illustrate both hand-held and bench-top processes. Here are links to more information on the equipment in these videos:
Hand-held demagnetizer: http://www.rbannis.com/products/handmags.html
Bench-top demagnetizer: http://www.em-chicago.com/Standard_Surface_Demagnetizers.html
The key part of de-magnetizing the ADIS16405 is to expose the device to alternating and decaying magnetic fields.
Hand-held Process
The following video shows the hand-motion that we use to de-magnetize an ADIS16405. The combination of circular and raising motion helps create both alternating and decaying fields.
NOTE: Keep the unit away from the probe or turn the probe off if it must return to a location near the unit after completing this process.
Bench-top Process
This process is a little simpler. Rotate the device on its surface a few times, then lift it away from the surface of the instrument.
NOTE: Keep the unit away from the demagnetizer surface or turn the instrument off if before returning the unit to a location near the surface.