Method and system for determining the depth of an electrically conductive body in a medium having a known conductivity and a known permeability by measuring phase difference between a primary and secondary magnetic field
First Claim
1. A method of determining the depth of an electrically conductive body in a medium having a known conductivity and a known permeability, comprising the steps of:
- generating a primary magnetic field from an electromagnetic wave transmitting means located a distance apart from said conductive body, said primary magnetic field having a time-varying field strength;
generating a first signal representing the time-varying field strength of said primary magnetic field;
transmitting the primary magnetic field from said transmitting means into the medium, wherein the primary magnetic field induces an electric current in the conductive body, and the electric current generates a secondary magnetic field having a time-varying field strength and propagating outward from the conductive body and through the medium;
sensing the strength of the secondary magnetic field by a receiving means, said receiving means generating a second signal representing the time-varying field strength of said secondary magnetic field;
conducting said first and second signals to a comparator means;
the comparator means,processing said first and second signals to obtain a third signal having a value indicating the magnitude of a phase difference between said primary and secondary magnetic fields caused by the primary magnetic field propagating through the medium to the conductive body, and by the secondary magnetic field propagating outward from the conductive body and through the medium; and
transmitting the third signal to a processor means, the processor meanscalculating the depth of the conductive body in the medium from the third signal and the conductivity and permeability of the medium.
1 Assignment
0 Petitions
Accused Products
Abstract
A method and system for determining the depth of an electrically conductive body in a medium having a known conductivity and a known permeability. The method comprises the steps of generating a primary magnetic field having a time-varying field strength, and transmitting that primary magnetic field into the medium. The primary magnetic field induces an electric current in the conductive body, and this electric current generates a secondary magnetic field that also has a time-varying field strength and that propagates outward from the conductive body and through the medium. The method of this invention further includes the steps of sensing the strength of that secondary magnetic field, comparing the primary and secondary magnetic fields to measure the phase difference therebetween, and then calculating the depth of the conductive body in the medium from the detected phase difference.
-
Citations
29 Claims
-
1. A method of determining the depth of an electrically conductive body in a medium having a known conductivity and a known permeability, comprising the steps of:
-
generating a primary magnetic field from an electromagnetic wave transmitting means located a distance apart from said conductive body, said primary magnetic field having a time-varying field strength; generating a first signal representing the time-varying field strength of said primary magnetic field; transmitting the primary magnetic field from said transmitting means into the medium, wherein the primary magnetic field induces an electric current in the conductive body, and the electric current generates a secondary magnetic field having a time-varying field strength and propagating outward from the conductive body and through the medium; sensing the strength of the secondary magnetic field by a receiving means, said receiving means generating a second signal representing the time-varying field strength of said secondary magnetic field; conducting said first and second signals to a comparator means;
the comparator means,processing said first and second signals to obtain a third signal having a value indicating the magnitude of a phase difference between said primary and secondary magnetic fields caused by the primary magnetic field propagating through the medium to the conductive body, and by the secondary magnetic field propagating outward from the conductive body and through the medium; and transmitting the third signal to a processor means, the processor means calculating the depth of the conductive body in the medium from the third signal and the conductivity and permeability of the medium. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 27, 28)
-
-
12. A method of determining the depth of an electrically conductive body in a medium having a known conductivity and a known permeability, comprising the steps of:
-
generating in a second medium a primary magnetic field from an electromagnetic wave transmitting means located a distance apart from said first medium, said primary magnetic field having a time-varying field strength; generating a first signal representing the time-varying field strength of said primary magnetic field; transmitting the primary magnetic field from said transmitting means into the first medium, wherein the primary magnetic field induces an electric current in the conductive body, and the electric current generates a secondary magnetic field having a time-varying field strength and propagating outward from the conductive body, through the first medium and into the second medium; sensing the strength of the secondary magnetic field by a receiving means located in the second medium, said receiving means generating a second signal representing the time-varying field strength of said secondary magnetic field; conducting said first and second electric signals to a comparator means;
the comparator means,processing said first and second electrical signals to obtain a third signal having a value indicating the magnitude of a phase difference between said primary and secondary magnetic fields that is caused by the first medium as (i) the primary magnetic field is transmitted therethrough to the conductive body, and (ii) the secondary magnetic field propagates outward from the conductive body and through the first medium; and transmitting the third signal to a processor means, the processor means calculating the depth of the conductive body in the first medium from the third signal and the conductivity and permeability of the medium. - View Dependent Claims (13, 14, 15, 16, 17, 18)
-
-
19. Apparatus for determining the depth of an electrically conductive body in a medium having a known conductivity and a known permeability, comprising:
-
transmitting means located a distance apart from said conductive body to generate a primary magnetic field having a time-varying field strength, and to transmit the magnetic field into the medium, wherein the magnetic field induces an electric current in the conductive body, and the electric current generates a secondary magnetic field having a time-varying field strength and propagating outward from the conductive body and through the medium, said transmitting means further including a means for generating a first signal representing the time-varying field strength of said primary magnetic field; receiving means to sense the secondary magnetic field and to generate a second signal proportional to the strength thereof; phase shift detecting means connected to the receiving means to receive said second signal therefrom, and further adapted to receive said first signal from said transmitting means, wherein said phase shift detecting means further includes comparator means for processing said first and second signals and to generate therefrom a third signal having a value indicating the magnitude of a phase difference between said primary and secondary magnetic fields caused by the medium as the primary magnetic filed is transmitted through the medium to the conductive body, and as the secondary magnetic field propagates outward from the conductive body and through the medium; and depth determining means connected to the phase shift detecting means to receive said third signal therefrom and to calculate the depth of the conductive body from the third signal and the conductivity and permeability of the medium. - View Dependent Claims (20, 21, 22, 23, 29)
-
-
24. A method of determining the depth of an electrically conductive body in a medium having a known conductivity and a known permeability, comprising the steps of:
-
generating a primary magnetic field from a transmitting means located a distance apart from said conductive body, said primary magnetic field having a time-varying field strength; generating a first signal representing the time-varying field strength of said primary magnetic field; transmitting the primary magnetic field from said transmitting means into the medium, wherein the primary magnetic field induces an electric current in the conductive body, and the electric current generates a target secondary magnetic field having a time-varying field strength and propagating outward from the conductive body and through the medium; sensing the strength of the secondary magnetic field by a receiving means and generating therefrom a second signal representing the time-varying field strength of said secondary magnetic field; conducting said first and second electrical signals to a comparator means; the comparator means, processing said first and second signals to obtain a third signal having a value indicating the magnitude of a phase shifted target returns in the primary and secondary magnetic fields that is caused by the medium as (i) the primary magnetic field is transmitted through the medium to the conductive body, and (ii) the secondary magnetic field propagates outward from the conductive body and through the medium; transmitting the third signal to a processor means, the processor means calculating the depth of the conductive body in the first medium from the third signal and the conductivity and permeability of the medium. - View Dependent Claims (25, 26)
-
Specification