Desarrollo de un sistema de adquisición automática de datos de resistividad

Abstract

An automatic data acquisition system for field resistivity measurements was developed at CICESE. The system applies a known current to the ground, measures the induced voltage, and calcula tes the apparent resistivity. Ali measurements are converted to digital format, ata maximum sarnpling rate of 40 sarnples/sec. In this manner, the system collects large quantities of data that allow the calculation of statistical pararneters which, in turn, permit to estímate the reliability of the measurements. The device has been designed to supply a maximum power of 5 KW, at a maximum voltage of 1000 V, DC.  The polarity of the applied current is inverted periodically to avoid the effects of electrolythic polarization caused by a unidirectional current. Also, the measured voltages are averaged to compensa te the effects of self potential. The system is controlled by a microcomputer (AIM-65 from Rockwell), that allows it to be prograrnmed for different ranges of operation and perform sorne of the data processing in the field. The cost in components of the equipment is low compared with similar systems of manual operation. At present, the first prototype has been developed and tested in the field and the results obtained have been satisfactory.