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kemal
9a1033973d
The accelerometer and gyroscope were logged and never used. They measure nothing about weather, but they do measure the one thing about this station that nothing else can see: whether the sensor is still where it was. Measured over four and a half days on the real station, four genuine movements each stepped the temperature by a median of 1.02 C, against an ordinary fifteen minute change of 0.107 C with a 95th percentile of 0.841. A move therefore lands past the 95th percentile of normal variation. The heads carry about 55 hours of memory, so an undeclared move contaminates two days of training with a discontinuity they will try to fit rather than ignore. This now gets the same treatment set_environment gives a window being opened, because it is the same event: the coupling between the sensor and what it is measuring changed, and nothing in the data says so. Three choices in here were made by measurement, and the obvious one was wrong. Raw accelerometer looks like the natural input and is not. Over the same record a gravity-vector detector fires 112 times against this one's 4, because RTIMULib's gyro fusion removes exactly the desk vibration a bare accelerometer picks up. The fused pitch and roll have a p99 sample-to-sample noise of 0.0001 degrees, so a one degree trigger carries four decades of headroom. Yaw and compass are excluded. They are the only attitude outputs that depend on the magnetometer, and indoors the magnetometer is measuring the building. RTIMULib restarts its fusion from a default attitude when SenseHat is reconstructed, which put an 18 degree step in the record on every one of this station's seven service restarts. Without a settle window every deploy would queue a retrain. 300 seconds rather than 180: one artifact appeared three minutes after a restart, still converging. Replayed against the full record the detector finds 4 genuine movements and leaks 0 artifacts.