APPARATUS AND METHOD FOR DETERMINING EARTH'S NEAR-SURFACE PROPERTIES WITH ON-TIME MEASUREMENTS FROM AIRBORNE TIME-DOMAIN ELECTROMAGNETIC DATA

摘要

A device and method for calculating electrical properties of a surveyed underground formation. The method includes selecting (1300) a waveform (300) having multiple current transition rates; placing (1302) a time-domain electromagnetic (TEM) system (1100) above the underground formation while generating with a transmitter (1102) a transient primary magnetic field during an on-time period and no magnetic field during a following off-time period, due to the waveform (300); and recording (1304) with a receiver (1104) magnetic related data generated by the earth as a result of the transient primary magnetic field. The receiver (1104) records the magnetic related data during the on-time period using plural on-time gates sampling.