The output from the arcsin function has a swing of ±90°, but the accuracy generally decreases when too close 90° or -90°, as there is not much variance in the output voltage for those regions. In general, this leaves an operating region of ≈±80°. Therefore, the magnet needs to be roughly positioned so that the desired measurement range falls within the ±80° region. The accuracy for this method largely depends on the spacing between the calibration points, which can be estimated using Equation 8.

Figure 4-20, Figure 4-21, and Figure 4-22 each show an example of a possible error curve for this setup with a different number of calibration points, calibrated between ±80°.

Figure 4-20 One Sensor Peak Calibrated Plus Lookup Table Error, 3 Cal Point, ≈ 4° Peak-to-Peak Error

Figure 4-22 One Sensor Peak Calibrated Plus Lookup Table Error, 9 Cal Points, ≈ 1° Peak-to-Peak Error

Figure 4-21 One Sensor Peak Calibrated Plus Lookup Table Error, 5 Cal Points, ≈ 2° Peak-to-Peak Error