Design and Construction of a Geo-electric Node System for Earth Resistivity Meters

Abstract

A sixteen-node geo-electric system is presented. The multi-electrode switching array can be used with any earth-resistivity meter and consists of a control unit which interfaces resistivity meter by means of four wires (two current wires and two potential wires) with sixteen geo-electric nodes, connected to the control unit via a network of a seven-core cable. The control unit uses PIC16F877 interfaces with a telephone keypad to select the wanted electric node, two seven-segment LED for display, four switches for line selection and four LEDs for line indicator. Each electric node has been designed by using PIC16F84 and four relays for electrode switching. Two wires are sued for the RS-485 bus driver between the control unit and each electric node for communication. The system can be expanded up to 32-electric nodes within a range of 3 kilometer