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This paper considers the possibilities of using digital feedback for precise anisotropic magneto-resistance (AMR) magnetometers using commercial off-the-shelf (COTS) components. Requiring only a few analog parts, most of the signal processing is done digitally within an STM32 microcontroller. Because most of the precision is made by the feedback circuit, the analog-to-digital converter (ADC) can be a low-cost type. The compensation source is made with a pulsewidth modulation-driven H-bridge sourced from a voltage reference, so the cost reduction when compared to a “full-analog” design is large. The demodulation of a flipped-AMR signal is done with software after the AD conversion because it improves the offset stability and brings the reduction of the preamp’s and ADC’s LF noise. This paper presents the full characterization of a real instrument, including its noise, linearity, stability, and power consumption. [ABSTRACT FROM AUTHOR]

This paper describes a novel method for calibrating dc-precise magnetometers in the low field range ($\pm 100~\mu \text{T}$), which gives acceptable results even in laboratory conditions with significant magnetic interference. By introducing a closely mounted reference magnetometer and a specific calibration procedure, it is possible to compensate for the external magnetic field disturbances caused, e.g., by the local transportation operated with dc power supplies. The field compensation occurs only shortly after the calibrating coils are energized. In this case, the leakage of the coil’s magnetic flux to the reference sensor due to the cancelation of the time-varying compensating field was negligible. When using 60 cm coils and reference sensor in 2.5 m distance, we were able to calculate magnetometer gains with a standard deviation of 91 ppm. We show that an overall uncertainty of 0.1% can be achieved. [ABSTRACT FROM AUTHOR]

DC/AC yokeless galvanically insulated electric current sensors are required for applications, e.g., in automotive and aerospace engineering, where size, weight, and/or price are strictly limited. A busbar current sensor with differential fluxgate in the hole has 1000 A range and 10 mA resolution. Using an asymmetric shape, we achieved a frequency error below ±3% up to 1 kHz, while keeping high temperature stability and low sensitivity to mechanical misalignments. The 2.5 mA/°C maximum dc drift is four times better than when using an AMR sensor and 1000 times better than when using a Hall sensor. The sensor linearity error is below 0.1%. [ABSTRACT FROM PUBLISHER]