Development of a Low-Cost Portable 3-Dimensional Hybrid Magnetometer System for Vector and Magnitude Geomagnetic Field Logging

This study presents the design, development, and performance evaluation of a low-cost, portable 3-Dimensional hybrid magnetometer system integrating an Anisotropic Magneto-Resistive (AMR) sensor and a custom proton precession mechanism. Standard commercial proton precession magnetometers primarily measure scalar field magnitudes, limiting their capability in 3-axis vector field orientation and real-time directional mapping. To overcome these limitations, a hybrid logging platform was constructed by interfacing an HMC5883L 3-axis AMR sensor and a hydrocarbon-based (kerosene) proton precession coil with an ATmega micro-controller platform. The system incorporates a high-resolution 24-bit Analog-to-Digital Converter (ADS1256), a Real-Time Clock (DS1307), a 16 x 4 Liquid Crystal Display, and an SD card data logging module operating at 5-second sampling intervals in CSV format. Comparative field calibration was conducted along a 300-meter baseline at Adekunle Ajasin University, Akungba-Akoko, alongside a benchmark commercial magnetometer (GSM-19T). The developed unit exhibited signal signatures closely tracking the commercial standard. Regional residual field profiling along the Aiyegunle–Supare road yielded intensity ranges of 52.18 nT to 140.27 nT (AMR) and 46.46 nT to 124.89 nT (proton sensor). Along the Emure–Supare road, residual field values ranged from 201.52 nT to 226.92 nT (AMR) and 179.42 nT to 202.04 nT (proton sensor). The system offers enhanced portability, simultaneous tri-axial vector logging, low power consumption, and significant cost reduction, demonstrating high viability for geophysical surveys, environmental mapping, and localized magnetic anomaly detection.