A geophysical tracking and data logging system: description and case history

Abstract

An Ultrasonic Ranging and Data System (USRADS) has been developed and interfaced with a Geonics EM31 terrain conductivity meter. The system tracks the EM31 operator's position by measuring the traveltime of ultrasonic pulses from a transducer carried in a backpack, to microphones mounted on stationary receivers deployed in the survey area. A microprocessor-controlled radio transmitter, also carried in the backpack, transmits the terrain conductivity data to a mobile base station (van or truck), where the EM31's X-Y position, and the electromagnetic quadrature and in-phase readings are automatically recorded each second by a portable computer. USRADS can track the surveyor for distances of up to about 120 m from the base station with an accuracy of about 10 cm. A field study is discussed where roughly 8000 m2 of Solid Waste Storage Area 4 (SWSA 4) on the Oak Ridge Reservation is surveyed, collecting over 2700 in-phase and quadrature measurements in 45 minutes. The high density of measurements provided sharp resolution of waste trench boundaries. -from Authors