Is it normal for the LSM9DS1 magnetometer offsets to change?

[Zach1]

We have the LSM9DS1 installed in some sensors we have. We calibrate them all in the office before taking them out to measure magnetic data. When we go to analyze the data there appears to be an offset or drift in the magnetometer readings that can be up to about 0.01-0.5 Gauss. Is it normal to see changes in the magnetometer offsets over time or after transportation?

[Eleon BORLINI]

Hi @Zach​ , 10 mg and above is quite high offset for just a transportation. My questions are: which FS did you selected? And, more important, to which kind of transportation was the magnetometer subjected? It seems an hard iron magnetization... Is the same in the 3 axis? Btw, maybe it's not the case, but if the transportation path is constant for the application, and the offset is constant (at least in the last path point), you could compensate it in the registers from OFFSET_X_REG_L_M (05h) to OFFSET_Z_REG_H_M (0Ah). Regards

[Zach1]

The FS settings are +/- 16 Gauss on each axis.

The offsets aren't the same in each axis, and the offsets vary by device.

The magnetometers are installed in small, battery powered devices which we ship to a variety of locations. We mostly transport them by car to a variety of locations (so we just put them in a suitcase in the trunk). Sometimes we mail them (through, e.g., UPS). Cheers.

[Eleon BORLINI]

Hi @Zach​ , ok, so you should see max 1mG offset variation... another question: have you ideas of which magnetic field amplitude the parts can be subjected? Because if the Magnetic disturbance field is above 50 G, the Zero-gauss offset starts to degrade, as pointed in LSM9DS1 datasheet. Regards

[Zach1]

It wouldn't have seen magnetic fields higher than 8 Gauss as far as I know. We do have them near either A-batteries or polymer batteries, which I think might be causing it, so its useful to know how magnetometers usually perform. Maybe you could comment on that, otherwise thanks for the quick responses! Cheers.