Method for magnetically detecting a localized disturbance of the ground
First Claim
1. A method of detecting the presence of a localized disturbance of the ground comprising the steps of sweeping an area of the ground with a detector which is responsive to a magnetic gradient and which comprises a plurality of mutually spaced apart detector units, detecting a change in the output from the detector units due to a change in magnetic gradient caused by the localized disturbance and not by any magnetic object and producing a signal capable of direct human perception when such change is detected.
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Abstract
The invention is predicated upon the fact that a buried object causes a disturbance of the local value of the earths magnetic field due to both the disruption of the soil and the material of the object. The change in intensity of the field will usually be to small to detect reliably, but the horizontal and/or vertical gradients of the magnetic disturbance is detectable. A method of detecting a localized disturbance of the ground is disclosed in which a plurality of mutually spaced apart detector units are swept across an area of ground suspected of containing a localized disturbance and in which the detector units are responsive to the magnetic field gradient associated with the resulting disturbance of the load magnetic field. Non-metallic objects may be detected.
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Citations
10 Claims
- 1. A method of detecting the presence of a localized disturbance of the ground comprising the steps of sweeping an area of the ground with a detector which is responsive to a magnetic gradient and which comprises a plurality of mutually spaced apart detector units, detecting a change in the output from the detector units due to a change in magnetic gradient caused by the localized disturbance and not by any magnetic object and producing a signal capable of direct human perception when such change is detected.
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10. A method for detecting a physical disturbance of the ground defined by a boundary between disturbed ground and undisturbed ground, the method comprising the steps of sweeping an area of the ground with a detector which is responsive to a magnetic gradient, generating a signal indicative of the magnetic gradient at the boundary between the disturbed and undisturbed ground, and producing an output capable of direct human perception in response to the signal.
Specification