The most important milestone in the field of magnetic sensors was when AMR sensors started to replace Hall sensors in many applications where the greater sensitivity of AMRs was an advantage. GMR and SDT sensors finally found applications. We also review the development of miniaturization of fluxgate sensors and refer briefly to SQUIDs, resonant sensors, GMIs, and magnetomechanical sensors.

A calibration procedure for calibrations of triaxial magnetometers is presented. The procedure uses a triaxial Helmholtz coil system and an Overhauser scalar magnetometer and is performed in the Earth's field range. The triaxial coils are first calibrated with the Overhauser magnetometer, and subsequently, a triaxial magnetometer calibration is performed. As opposed to other calibration approaches, neither Earth's field nulling system nor movements of the magnetometer are needed. A real calibration test was carried out-the extended calibration uncertainty was better than 430 ppm in sensitivity and 0.06° in orthogonality.