Optimal Requirements of a Data Acquisition System for a Quadrupolar Probe Employed in Electrical Spectroscopy

TL;DR

This paper analyzes the optimal requirements for a quadrupolar probe used in electrical spectroscopy to ensure accurate, non-invasive subsurface measurements of resistivity and permittivity, emphasizing the importance of sampling mode.

Contribution

It provides an analytical and numerical comparison of IQ and uniform sampling modes, demonstrating the superiority of IQ sampling for this application.

Findings

IQ sampling yields lower inaccuracies than uniform sampling.

Performance depends significantly on the chosen sampling mode.

Numerical simulations confirm the advantages of IQ sampling under various conditions.

Abstract

This paper discusses the development and engineering of electrical spectroscopy for simultaneous and non invasive measurement of electrical resistivity and dielectric permittivity. A suitable quadrupolar probe is able to perform measurements on a subsurface with inaccuracies below a fixed limit (10%) in a bandwidth of low (LF) frequency (100kHz). The quadrupole probe should be connected to an appropriate analogical digital converter (ADC) which samples in phase and quadrature (IQ) or in uniform mode. If the quadrupole is characterized by a galvanic contact with the surface, the inaccuracies in the measurement of resistivity and permittivity, due to the IQ or uniform sampling ADC, are analytically expressed. A large number of numerical simulations proves that the performances of the probe depend on the selected sampler and that the IQ is better compared to the uniform mode under the same operating conditions, i.e. bit resolution and medium.