Fig. 5

Examples from calibrateCATS.m. A Magnetometer calibrations involve rotating the tag around the 3-axes of rotations in line with magnetic north. Bottom graph is a plot of the triaxial magnetometer data after the calibration is applied such that the overall magnitude of the 3-axes (the vector sum, |M|) is constant. B Gyroscope calibrations involve spinning the tag in six different positions (positive and negative for each axis) at two speeds. The actual speed is calculated from the peaks in the magnetometer data as 2-axes rotate through north and south poles. C Checking the flotation of new tags is critical. Bottom image—occasionally a small amount of ballast (in this case two US quarters) may need to be added for tags that were designed in warm water that are deployed in cold, more dense water to ensure that tags float upright (but still float)