| 摘要 |
A method for surveying terrain uses transient magnetic fields transmitted from a coil in plane parallel to and above the terrain, transient voltage response from vertically spaced receiver coils coaxial with and parallel to the transmitter coil being processed to detect highly conductive objects buried in the terrain, with the ratio of the response of the coils optionally being used to estimate the depth of objects. The responses from the coils are scaled in a predetermined ratio to provide cancellation of the response from objects in a layer of terrain at a particular depth, which layer may be at the surface to remove surface responses, or beneath the surface so as to allow surface objects to be differentiated from deeper objects by providing responses of opposite polarity.
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