Method and apparatus for the location of remote conductors by analysis of signals induced in an antenna array
First Claim
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1. A method for investigating buried conductors which act as electromagnetic signal sources by virtue of currents flowing in them, said method comprising:
- providing an antenna assembly which comprises three vertically spaced coils (A,B,C) whose axes are horizontal and two horizontally spaced coils (D,E) whose axes are vertical;
locating the antenna assembly over a region believed to contain one or more buried conductors of interest;
measuring the signals (D,E) induced in the two vertical-axis coils (D,E) and determining a measured difference value (D-E);
measuring the three respective signals (A,B,C) induced in the three horizontal-axis coils (A,B,C);
determining from said three respective signals and the known geometry of the antenna assembly a calculated difference value "(D-E)" that should be produced if the signals are induced by a single source;
comparing the measured and calculated difference values thereby to obtain an indication of the singularity of the source or, as the case may be, an indication of the separation of plural sources.
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Abstract
An antenna array has three horizontal coils (A,B,C) with equal spacings s, and two coplanar vertical coils (D,E) with a horizontal spacing 2f. When it is located over one or more current-bearing buried conductors, signal currents (A,B,C,D,E) are induced in the coils. The difference value D-E is measured and compared with a value "D-E" calculated from the equations:
"(D-E)"=2f/("d".sup.2 +f.sup.2)
"d"=2s(B-C)/ A-B)-(B-C)!.
Identity indicates that the signal source is a single conductor. A larger calculated value indicates plural sources with mainly vertical separation. A small calculated value indicates plural sources with mainly horizontal separation.
3 Citations
8 Claims
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1. A method for investigating buried conductors which act as electromagnetic signal sources by virtue of currents flowing in them, said method comprising:
providing an antenna assembly which comprises three vertically spaced coils (A,B,C) whose axes are horizontal and two horizontally spaced coils (D,E) whose axes are vertical;
locating the antenna assembly over a region believed to contain one or more buried conductors of interest;
measuring the signals (D,E) induced in the two vertical-axis coils (D,E) and determining a measured difference value (D-E);
measuring the three respective signals (A,B,C) induced in the three horizontal-axis coils (A,B,C);
determining from said three respective signals and the known geometry of the antenna assembly a calculated difference value "(D-E)" that should be produced if the signals are induced by a single source;
comparing the measured and calculated difference values thereby to obtain an indication of the singularity of the source or, as the case may be, an indication of the separation of plural sources.- View Dependent Claims (2, 3, 4, 5)
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6. Apparatus for investigating buried conductors which act as electromagnetic signal sources by virtue of currents flowing in them comprising an antenna assembly which comprises three vertically spaced coils (A,B,C) whose axes are horizontal and two horizontally spaced coils (D,E) whose axes are vertical;
- comparator means for determining a measured difference value (D,E) between signals induced in the two vertical-axis coils;
data processing means coupled to said horizontal axis coils for receiving signals induced in said horizontal axis coils and arranged to calculate, on the basis of the received signals and the known geometry of said antenna assembly, a calculated value ("D-E)") of the difference value between the signals induced in the two vertical axis coil that should be produced if the signals are induced in the two vertical axis coils by a single source. - View Dependent Claims (7, 8)
- comparator means for determining a measured difference value (D,E) between signals induced in the two vertical-axis coils;
Specification
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Current AssigneeMark Ian Howell
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Original AssigneeMark Ian Howell
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InventorsHowell, Mark Ian
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Primary Examiner(s)Snow, Walter E.
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Application NumberUS08/573,381Time in Patent Office690 DaysField of Search324/66, 324/67, 324/326, 324/327, 324/328, 324/329US Class Current324/326CPC Class CodesG01V 3/081 the magnetic field is produ...
