Optimal requirements of a data acquisition system for a quadrupolar probe employed in resistivity and permittivity surveys

Abstract

This paper discusses the development and engineering of a suitable quadrupolar probe for simultaneous and non invasive surveys of electrical resistivity and dielectric permittivity. The 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 should be connected to an appropriate analogical digital converter (ADC) which samples in phase and quadrature (IQ) or in uniform mode. If the probe 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.