| 摘要 |
<p>PURPOSE:To obtain an electromagnetic surveying method capable of exactly measuring underground structure by minimizing the effect of the geography and the structure near the ground surface, the effect of external and environmental noise and source overprint. CONSTITUTION:In this method, the relative resistance underground distribution is electromagnetically surveyed by using a transmission loop 10 and a plurality of reception loops 20-1 and 20-2 placed in the measuring point on the ground surface side. An adjustment process for forming an output synthesizing circuit 40 to synthesize the output of each reception loop 20-1, 20-2 so as to cancel the adjustment output obtained from each reception loop 20-1, 20-2 at the moment sending alternating current for adjustment to the transmission loop 10, and an underground electromagnetic surveying process in time region for detecting and storing the decay of eddy current from the output of an output synthesizing circuit 40 as the time-function change in an electromagnetic field by sending transmission current to the transmission loop 10, terminating the transmission current and generating the smoke ring phenomenon in which the eddy current transmits underground, are repeatedly applied to each measuring point. And, based on the memory data for each measuring point, the relative resistance underground distribution is calculated.</p> |
