Combined Frequency Domain and Time Domain Data Processing in Airborne Electromagnetics

Abstract

We describe the main properties of the EQUATOR airborne electromagnetic system and how the system is employed to process data in both time- and frequency domains. To the best of our knowledge, EQUATOR is the only system to collect electromagnetic data both in time and in frequency domains. We explain the difference between the two methods on some numerical and field examples. Also, we describe some advantages of their coupling. In particular, by virtue of our approach, a numerically more robust solution of one-dimensional electromagnetic inverse problem may be achieved. The recorded full-time measurements are further converted to in-phase, quadrature and off-time responses, as opposed to standard frequency or time domain solutions, which have been widely adapted within the industry. When inverting the data, our main focus is within the top 200 m of the Earth. We emphasize that a combined use of frequency and time domain data gives more detailed information about geological structures in the near-surface.