| 摘要 |
PURPOSE:To measure movement or subsidence of ground precisely by laying plural high-frequency coils under the underground to be measured in the direction of the depth in order making the axial direction parallel and detecting the magnetic force sent out from these coils with a magnetic coil with two axes. CONSTITUTION:The electromagnetic coil 1 detecting generating signals of the high-frequency coils 4-1-4-n is constituted with two axes of a Z direction and an X direction so that the positions of the high-frequency coils can be discriminated from the magnetic flux direction and force of the generating signals. Since the high-frequency signals become smaller in inverse proportion to a square - cubic of the distance when the distance from the signals to the high- frequency coils is separated, the winding with a number of times of winding is performed on a magnetic core with high permeability so that the weak signals can be detected. Th high-frequency signals from an oscillator 6 are amplified and given to the high-frequency coils 4-1-4-n and the high-frequency signals sensed with the coils indicating the Z direction of the electromagnetic coil 1 and the high-frequency signals sensed with the coils indicating the X direction of the coil 1 are received with a receiver 2a and a receiver 2b respectively.
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