Design and Error Analysis of Geomagnetic Measurement Circuit Based on Triaxial Magneto-Resistive Sensor

Geomagnetic induction intensity is popularly sensed by those small size and simplicity of wheatstone bridge based magneto-resistive sensors. However, the output signal is small for the field is weak, and high magnification is needed. To solve this problem, circuit with 'Y'-shaped feedback structure based on triaxial magneto-resistive sensor was designed to obtain high magnification. Error analysis of the hardware circuit was then presented. Analysis results showed that larger errors were brought about with increasing geomagnetic field intensity. Finally, static sampling was finished, through which the geomagnetic field was measured to be 52848 nT, as well as 53520.24 nT gained by high-precision triaxial fluxgate magnetometer FVM400. The difference between them two was only 1.26%. The results showed that the circuit had achieved the measurement requirements, with simple structure, good stability, and high accuracy.