High-resolution analog-to-digital converter-based data acquisition system for geoelectrical prospecting

Electrical resistivity surveying is a fundamental geophysical technique for subsurface characterization, based on the measurement of apparent resistivity using the four-point method. The reliable acquisition of these data requires high-resolution and stable instrumentation, capable of detecting small variations in electrical signals. This article presents the development of a low-cost, high-resolution data acquisition system based on a 24-bit analog-to-digital converter (ADC), which enables the recording of injected currents and resulting voltages in the subsurface. The system incorporates automatic polarity reversal, allowing the discrimination of spontaneous potential and improving the quality of the measurements. The system was validated through laboratory tests of linearity, repeatability, temporal stability, and dynamic range, using precision resistors and comparing the results with a commercial resistivity meter. The results demonstrate stable and reproducible performance, with the capability to measure low-magnitude signals, making the system suitable for electrical resistivity surveying applications.