Gyro is not a compass. The only thing it measures is the angular velocity.
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I think the reason is that the fan motor produces an electromagnetic field, which perturbs the Earth’s magnetic field sufficiently to interfere with the headset sensor. I would have thought that my base station would provide a fixed reference point, but I still get drift. It makes me wonder if some headsets have a sensor problem.
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But is the sensor a true gyro? My EDTracker (headtracker) has a complicated calibration sequence (requiring orienting and turning the sensor in various directions). It is definitely affected by magnetic fields. (They mention it in the doc.)
I suppose the obvious questions is, this something that can be remedied through software or a limitation of the technology being used?
Better calibration helps. The headtracker is what made me think of the fan, when my 8K started drifting so much. If I calibrated the headtracker with the fan off, it would drift when the fan was on. If I calibrated with the fan on, it would drift the other way when the fan was off.
I’m not sure what calibration is available for the Pimax. I don’t recall seeing it mentioned. I did contact Pimax Support about the issue, but they had no suggestions.
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Technically, gyro is just gyro, (linear) accelerometer is a (linear) accelerometer and compass is a compass. Sometimes the two (or all) things are combined into an IMU (inertial measurement unit). The hardware used to implement those is MEMS (micro-electro mechanical sensor).
If you need to turn the thing into separate directions the chances are there is a (magnetic) compass in it, but gyro alone does not need it (and cannot need it), or you can also use gravity as a fixed acceleration to calibrate the linear accelerometer.
Normal lighthouse tracked device (headset, controller, puck) has (apart from the optical sensors) also an IMU (with a linear accelerometer and a gyroscope), but no compass.
Just for the record:
- Linear accelerometer (as the name suggests) measures the linear acceleration (and only that).
- MEMS gyro measures the angular velocity (and only that)
- Compass measures the magnetic field.
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You can of course put any word on the gold scales. The technically inexperienced should be clear that I mean the combination of all Parts in the 6dof sensor.
Nobody here in germany says on the street, my drone have a Accelerometer-gyroscop-magnetometer… he says, he has a gyro.
The question was about an electrical recalibration. 
I would suggest trying the room setup again. They very well could be utilizing when you place the headset on the flat surface of the floor. It does say calibrating I think. And I’m not being sarcastic at all, this time. This is when they would set reference levels for such things. It would explain why adding the fan into the play space may cause such subtle variation.
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People miss my sarcasm too. 
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It is hard to take all this seriously, all the time, after being around a while. I’m still having fun with my “Pimax Experience” look forward to more. Its been interesting. There is so much more instore I hope. Kevin and Martin are more obligated to take it serious. Hopefully someday I’ll be able to share a beer and a laugh with the pimax crew and fans!
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