System for detecting a cable buried under the seabed
First Claim
1. A system for detecting a cable comprising;
- (a) means for applying an alternating current in the cable to be detected so as to produce magnetic flux around the cable,(b) a vehicle(c) a three dimensional flux detector having three detector elements each having cosine sensitivity characteristics mounted on said vehicle, the maximum sensitivity direction of each element being perpendicular to one another, and the maximum sensitivity direction of one of the detector elements being directed in the vertical direction,(d) means for separating the output signals of each of said detector elements into a DC component which is caused by the earth'"'"'s magnetic field and an AC component which is caused by said alternating current,(e) means for determining the direction of the cable from the DC and AC output components of two detector elements which have their directivity in the horizontal plane,(f) means for determining the horizontal distance and the vertical distance between the cable and the cable detecting system from the AC output signals of each of the detector elements on the principle that the magnitude of the flux is inversely proportional to the distance to the cable and the direction of the flux is in the tangential direction of the circle having the center on the cable.
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Abstract
A cable buried under a sea bottom is located by causing to flow in the cable an AC current, and measuring the magnetic flux near the cable. The present cable location system comprises (a) a vehicle for mounting a flux detector, (b) means for applying an alternating current in the cable to be detected, to produce magnetic flux around the cable, (c) a three dimensional flux detector having three detector elements, each having cosine sensitivity characteristics, mounted on said vehicle, the maximum sensitivity direction of each element being perpendicular to one another, and the maximum sensitivity direction of one of the detector elements being directed in the vertical direction, (d) means for separating the output signals of each of said detector elements into a DC component which is caused by the earth'"'"'s magnetic field and an AC component which is caused by said alternating current, (e) means for determining the direction of the cable from the DC and AC output signals of two detector elements which have directivity in the horizontal plane, and (f) means for determining the horizontal distance and the vertical distance between the cable and the cable detecting system from the AC output signals of the detector elements based on the principle that the magnitude of the flux is inversely proportional to the distance to the cable and the direction of the flux is in the tangential direction of a circle having the center on its cable.
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Citations
9 Claims
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1. A system for detecting a cable comprising;
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(a) means for applying an alternating current in the cable to be detected so as to produce magnetic flux around the cable, (b) a vehicle (c) a three dimensional flux detector having three detector elements each having cosine sensitivity characteristics mounted on said vehicle, the maximum sensitivity direction of each element being perpendicular to one another, and the maximum sensitivity direction of one of the detector elements being directed in the vertical direction, (d) means for separating the output signals of each of said detector elements into a DC component which is caused by the earth'"'"'s magnetic field and an AC component which is caused by said alternating current, (e) means for determining the direction of the cable from the DC and AC output components of two detector elements which have their directivity in the horizontal plane, (f) means for determining the horizontal distance and the vertical distance between the cable and the cable detecting system from the AC output signals of each of the detector elements on the principle that the magnitude of the flux is inversely proportional to the distance to the cable and the direction of the flux is in the tangential direction of the circle having the center on the cable. - View Dependent Claims (2, 3, 4, 5)
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6. A system for detecting a cable comprising:
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means for applying an alternating current in the cable to be detected so as to produce magnetic flux around the cable; a three dimensional flux detector having three detector elements with mutually orthogonal sensitivity characteristics; means for directing the sensitivity of one of said detector elements in the vertical direction so that the other two detector elements have their maximum sensitivity directions in the horizontal plane; means for separating the output signals of said detector elements into a DC component which is caused by the earth'"'"'s magnetic field and an AC component which is caused by said alternating current; means for determining the direction of the cable as a function of the DC and AC components of the detector elements having their maximum sensitivity directions in the horizontal plane; and means for determining the horizontal distance and the vertical distance between the cable and the cable detecting system as a function of the AC output components of each of the detector elements. - View Dependent Claims (7, 8, 9)
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Specification