WO2012172435A2

WO2012172435A2 - Transverse electromagnetic gradiometer

Info

Publication number: WO2012172435A2
Application number: PCT/IB2012/001656
Authority: WO
Inventors: Dieter Wolfgang Blum
Original assignee: Rampart Detection Systems Ltd.
Priority date: 2011-05-13
Filing date: 2012-05-10
Publication date: 2012-12-20
Also published as: WO2012172435A3

Abstract

A transverse electromagnetic gradiometer is described that uses at least one inductive vector electromagnetometer having a magnetically permeable core, an induction coil and an electrostatic shield to feed an amplifier and signal processing arrangement for the detection and subsequent processing of harmonic signatures contained in extremely low-frequency radiation on the order of about 3 hertz to about 3 kilohertz. The transverse electromagnetic gradiometer detects harmonic signatures of various electrical loads, and can also be utilized to detect faulty distribution transformers, faulty streetlight ballasts, illegal power consumption, power bypasses, electrical leakage, poor or faulty neutral-ground bonds, and other conditions that provide characteristic and identifiable harmonic signatures. The transverse electromagnetic gradiometer can also be used to determine location in applications such as a mine collapse or the like. A computer system may further process the obtained harmonic signatures for improved identification capabilities.

Description

TRANSVERSE ELECTROMAGNETIC GRADIOMETER

CROSS REFERENCE TO RELATED PATENT APPLICATIONS

This application claims priority to United States Patent Application Serial No. 61/485,997 filed May 13, 201 1 entitled "Transverse Electromagnetic Gradiometer" by Dieter Wolfgang Blum of Aldcrgrovc, British Columbia, Canada.

TECHNICAL FIELD

The present invention. relates generally to the detection of electromagnetic radiation, and more particularly to the detection of extremely low-frequency (on the order of about 3 hertz to about 3 kilohertz) radiation using a transverse electromagnetic gradiometer as disclosed herein.

BACKGROUND ART

Extremely low frequency (ELF) radiation may be defined in the atmospheric science sense as having a frequency in the range of 3 hertz to 3 kilohertz, with this definition being used throughout this specification. Extremely low frequency radiation has correspondingly very long wavelengths and very low energies. Therefore, related antenna sizes are usually very large and are designed to respond to the magnetic field (H) component of the Extremely Low Frequency (ELF) electromagnetic radiation to be detected (instead of the electric field (E) component). Also, at the wavelengths of Extremely Low Frequency (ELF) radiation, detection/reception is typically in the near-field region (distances of less than one wavelength of the detected radiation).

Detection of natural ELF electromagnetic radiation has been intensively used and studied by atmospheric scientists, wherein large induction coils (for example, search coils) and induction coils having magnetically permeable cores (for example, loopsticks) are utilized. An example of such natural phenomenon is that of Schumann resonance.

These types of magnetic detection/receiving antennas and associated systems may be considered forms of magnetometers, and more specifically, forms of vector magnetometers (due to their directionality/sensitive axis), and even more specifically, forms of vector electromagnetometers (in that they respond to changing B fields, and not to relatively static background B fields such as that of the earths magnetic field.)

It has been noted in earlier magnetometer studies that the electrical power grid, operating at frequencies of 50 or 60 Hertz, provides B-field interference, and it has also been noted that ageing and failing streetlights also provide interference to both magnetometers via the B-field component and low-frequency ham radio receivers via the electrostatic field component. However, practical industrial, commercial or security applications for the detection of such weak and extremely low frequency signals has been heretofore unknown.

Accordingly, it is an object of the present invention to provide a planar electromagnetic gradiometer that yields angle / azimuth information about a source of electromagnetic radiation of interest.

It is another object of the present invention to provide a transverse electromagnetic gradiometer system capable of analyzing the frequency components (harmonics) present. It is another object of the present invention to provide a transverse electromagnetic gradiometer system that has greatly increased sensitivity at normally employed standoff distances.

It is a further object of the present invention to provide a transverse electromagnetic gradiometer system that produces harmonic profiling of electrical utility loads.

It is also an object of the present invention to provide a transverse electromagnetic gradiometer system that can be used for electrical utility distribution line tracing;

It is still a further object of the present invention to provide a transverse electromagnetic gradiometer system that can be used for electrical utility distribution line fault tracing.

It is another object of the present invention to provide a transverse electromagnetic gradiometer system that can be used for electrical utility distribution line neutral and ground fault tracing.

It is yet another object of the present invention to provide a transverse electromagnetic gradiometer system that can be used for electrical utility power distribution and delivery safety assessments.

It is still a further object of the present invention to provide a transverse electromagnetic gradiometer system that can be used for electrical utility power consumption and power theft assessments.

It is also an object of the present invention to provide a transverse electromagnetic gradiometer system that can be used in conjunction with a source of electromagnetic radiation to determine distance vectors in underground applications such as mine rescue beacons.

DISCLOSURE OF THE INVENTION

In accordance with the present invention, there is provided a transverse electromagnetic gradiometer that uses at least one inductive vector electromagnetometer having a magnetically permeable core, an induction coil and an electrostatic shield to feed an amplifier and signal processing arrangement for the detection and subsequent processing of hannonic signatures contained in extremely low-frequency radiation on the order of about 3 hertz to about 3 kilohertz.

The foregoing paragraph has been provided by way of introduction, and is not intended to limit the scope of the invention as described by this specification, claims and the attached drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will be described by reference to the following drawings, in which like numerals refer to like elements, and in which:

Figure 1 is a side view of an inductive vector electromagnetometer of the present invention:

Figure 2 is an end view of an inductive vector electromagnetometer of the present invention;

Figure 3 is a side view of the present invention as adapted for attachment to a planar surface of a vehicle:

Figure 4 is a top view of the present invention as adapted for attachment to a planar surface of a vehicle;

Figure 5 is a diagrammatic representation of the present invention deployed in a typical semi- urban environment:

Figure 6 is a schematic block diagram of the present invention; and

Figure 7 is a diagram depicting the present invention utilized with a mine beacon.

The present invention will be described in connection with a preferred embodiment, however, it will be understood that there is no intent to limit the invention to the embodiment described. On the contrary, the intent is to cover all alternatives, modifications, and equivalents as may be included within the spirit and scope of the invention as defined by this specification, claims and the attached drawings. BEST MODE FOR CARRYING OUT THE INVENTION

For a general understanding of the present invention, reference is made to the drawings. In the drawings, like reference numerals have been used throughout to designate identical elements.

The present invention will be described by way of example, and not limitation. Modifications, improvements and additions to the invention described herein may be determined after reading this specification and viewing the accompanying drawings; such modifications, improvements, and additions being considered included in the spirit and broad scope of the present invention and its various embodiments described or envisioned herein.

Referring to the present invention in detail, in Figure 1 there is shown a side view of an inductive vector , electromagnetometer of the present invention. The inductive vector electromagnetometer of the present invention may, in some embodiments of the present invention, be a modified magnetic loopstick antenna that includes, but may not be limited to, a novel electrostatic shield arrangement. The inductive vector electromagnetometer is comprised of an induction coil 20 made from a conductive material such as copper wire and wound upon a magnetically permeable core 10 that may be, for example, a ferrite core. The conductive material may, in some embodiments of the present invention, be further coated or insulated with, for example, a lacquer or similar coating or encapsulating material. In one embodiment of the present, a range of from about 5,000 turns to about 20,000 turns of wire around the magnetically penneable core 10 may be used. In one preferred embodiment, 10,000 turns of wire around the magnetically permeable core 10 may be used. This coil and core assembly is externally surrounded and partially but not completely encircled by an electrostatic shield 30 that may be made from, for example, a metal foil. In some embodiments of the present invention, the electrostatic shield 30 may also have a coating or covering. Such coatings or coverings may include paints, other metals, dielectric materials, or the like. In figure I it is diagrammatically shown that magnetic flux due to external B-fields 50 and 60 will preferentially enter and exit the permeable core 10, thereby inducing an attendant electromotive force (EMF) within the induction coil 20. In some embodiments of the presenting invention, the coil and core assembly is of a generally cylindrical shape, and the electrostatic shield 30 is also, in some embodiments of the present invention, of a generally cylindrical shape and of a size slightly larger than that of the coil and core assembly. In some embodiments of the present invention, the magnetically permeable core 10 has a recessed area for accommodating the induction coil 20. Such an arrangement resembles a bobbin or the like. In such an arrangement, the magnetically permeable core 10 has a diameter that is larger on each end than in the center portion. Other geometries for the magnetically permeable core may also be used.

With reference now to Figure 2, there is shown an end view of the inductive vector electromagnetometer of the present invention. Figure 2 shows the magnetically permeable core 10, the induction coil 20 and the external electrostatic shield 30. In some embodiments of the present invention, a non-conductive material is placed between the external electrostatic shield 30 and the induction coil 20. The non-conductive material may be, for example, a plastic, paper, fiberglass, or the like. Further, there exists a longitudinal slit 40 in the electrostatic shield 30 which generally runs the length of the coil and core assembly, thereby obviating the creation of a single short-circuited turn by the electrostatic shield 30.

Now turning to Figure 3, there is shown a side view of the present invention as adapted for attachment to a planar surface of a vehicle or the like. There is shown a system pedestal 50 (cover dome not shown for clarity), with an attachment device 60 such as. for example, a suction cup. The system pedestal 50 may be made from a material such as a plastic, fiberglass, or the like. A cover dome for protecting the electronics contained there within is not shown for clarity'i but essentially covers the components depicted in Figure 3. As shown, there are two inductive vector electromagnetometers of the present invention 70 and 80, each having electrostatic shields 90 and 95, with shield slits 91 and 96 respectively. Also shown are front end electronics 120, and electrostatic shield connections 100 and 1 10 thereto. Also shown are the signal connections 130 and 135 from the coils 70 and 80 respectively to the front end electronics 120. The front end electronics 120 will be further described by way of Figure 6 and the accompanying descriptive specification.

Figure 4 is a top view of the present invention as adapted for attachment to a planar surface of a vehicle. Shown here again is the pedestal 50, upon which are mounted the inductive vector electromagnetometers of the present invention 70 and 80. with electrostatic shields 90 and 95 having shield slits 91 and 96 respectively. Also depicted are the front end electronics 120, along with electrostatic shield connections 100 and 1 10, as well as signal connections 130 and 135. In some embodiments of the present invention, the inductive vector electromagnetometers are generally cylindrical and are mounted in a generally horizontal orientation with respect to the cylindrical axis of each inductive vector electromagnetometer. In some embodiments of the present invention, a first inductive vector electromagnetometer and a second inductive vector electromagnetometer are mounted in such a generall horizontal orientation, and the horizontal axis of each inductive vector electromagnetometer in not parallel one to the other. In some embodiments of the present invention, the two horizontal axis form a generally v-shaped intersection that is greater than zero degrees and less than, or, in some embodiments, equal to, ninety degrees.

Now shown in Fig. 5 is a diagrammatic representation of the present invention deployed in a typical semi-urban or residential environment. B way of example arid not limitation, system operation under North American electrical distribution conditions will now be described with the aid of Figure 5. Other electrical distribution systems outside of North America may also be used with the present invention.

Depicted in Figure 5 is a motor vehicle 220 which is carrying a preferred embodiment of the present invention 221 on its roof, along with a Global Positioning System (GPS) receiver/antenna 222. The vehicle 220 is shown on a street 200, flanked by sidewalks 201 and front yards 202. There is also shown a typical building 210, which has its electrical power delivered in one of two ways as will be further described. The typical building 210 has an electrical power consumption metering unit 214 disposed typically on an exterior wall as shown. The typical building 2 10 may be a commercial building, an apartment building, a condominium, a residence, or the like.

In one method of power delivery, electrical power to the meter 214 can be conveyed via a vertical drop 213 from an overhead feedpoint 21 1. The feedpoint 21 1 is typically serviced by an aerial service drop 207 from a transformer 205, located near the top of a power pole 204. The transformer 205 is fed from a distribution line that has a high-voltage conductor 206 located atop said power pole 204, and is neutral connected to earth ground via connection 203.

In a second method of power delivery, electrical power to the meter 2 14 arrives via a buried service drop and a vertical rise conductor 217 from a ground emplaced transformer 212, typically placed on a non-conductive pad. The transformer 212 typically services several dwellings via separate buried service lines. The transformer 212 is fed via a buried distribution line having a high-voltage conductor 218 from a high-voltage feeder 2 19 located underground, for example, under the roadway 200.

Also shown within the building 210 are electrical power consuming loads 216 fed by interior wiring 215. With further reference to Figure 5, and in describing in particular detail the types of low-frequency electromagnetic radiation that the preferred embodiment of the present invention can sense and detect, one can see that in its normal orientation (parallel to residences and power lines), the present invention 221 is immune and non-responsive to the interfering electromagnetic fields emanating from the three most commonly encountered interference sources.

The first of these interfering sources is the previously mentioned high-voltage conductor

206, whose electromagnetic field 225 can be seen to be substantially at right angles to the present invention 221 and will therefore be of minimal magnitude.

The second of these interfering sources is the previously mentioned high-voltage feeder

219, whose electromagnetic field is substantially at right angles to the present invention 221 and will also be of minimal magnitude.

The third of these interfering sources are three-phase high-voltage distribution lines, herein shown as 209, atop a power pole 208, whose electromagnetic field 226 can again be seen to be substantially at right angles to the present invention 221 and will also be of minimal magnitude.

Now with reference to the detection of the desired electromagnetic radiation sources, depending on standoff distance between the present invention 221 and the various sources, the faint electromagnetic field 228 due to the loads 2 16 will radiate outward and be detectable.

In the case of underground electrical service delivery, a slightly larger radiating electromagnetic field 227 will also be detectable at a distance. Further, some, but not all harmonic components due to the loads 2 6 will couple through the transformer 2 12 and will be detectable via a much larger radiating electromagnetic field 224.

In the case of overhead electrical service delivery, a fairly large radiating electromagnetic field 223 will be detectable, and in this case, all the harmonic components due to the loads 216 will be present.

Aside from detecting harmonics due to various loads as described, the present invention can also be utilized to detect faulty distribution transformers, faulty streetlight ballasts, illegal power consumption, power bypasses, electrical leakage, poor or faulty neutral-ground bonds, and the like.

Now shown in Figure 6 is a schematic block diagram of the transverse electromagnetic gradiometer of the present invention. Inductive vector electromagnetometers 300 and 301 can each be seen to feed the inputs of amplifiers 306 and 307 via lines 302 and 304. and 303 and 305 respectively. The outputs 308 and 309 of amplifiers 306 and 307 are then fed through lowpass filters 310 and 31 1 and then to respective analog-to-digital converters 314 and 315 via lines 312 and 313. The analog-to-digital converters 314 and 315 output digital data via lines 316 and 317 respectively to data acquisition processor 320, this processor also controlling the analog-to-digital converters 314 and 315 via lines 318 and 319 respectively.

The data acquisition processor 320 provides for digital signal pre-processing functions before data is coupled to communications and power supply (COMM/PWR) module 322 via lines 321. The communications and power supply (COMM/PWR) module 322 provides system power and ground via 324 and 323 and may, in some embodiments of the present invention, be in USB form. The communications and power supply (COMM/PWR) module 322 interfaces to an external signal processing and display processor/computer 326 via connection 325 that may. in some embodiments of the present invention, be a USB connection.

The computer 326 executes firmware and software routines for processing the sensed and detected electromagnetic radiation data and presents its output in a user friendly format on operator interface 330 via connection 329. The computer 326 may be electrically connected to the transverse electromagnetic gradiometer through a series of physical cables that may, in some embodiments of the present invention, pass through or be connected by, other components. In some embodiments of the present invention, the connection between the computer 326 and the transverse electromagnetic gradiometer may be wireless. The computer 326 further accepts Global Positioning System (GPS) data from Global Positioning System (GPS) receiver 327 via connection 328, and uses this for time and position time stamping purposes when acquiring data. In some embodiments of the present invention, data from the Global Positioning System (GPS) receiver 327 is stored on computer readable media. Further, in some embodiments of the present invention, data from the Global Positioning System (GPS) receiver 327 is correlated with harmonic signatures received from the transverse electromagnetic gradiometer.

The computer 326 receives and analyzes harmonic signatures from the transverse electromagnetic gradiometer. The harmonic signatures may be unique to the source of detected electromagnetic radiation data, and may further be stored on computer readable media. In some embodiments of the present invention, a collection of harmonic signatures may be stored on computer readable media for comparison with the harmonic signature received from the transverse electromagnetic gradiometer. The collection of harmonic signatures may also, in some embodiments of the present invention, be organized by signature type.

To further provide exemplary applications of the present invention, Figure 7 depicts the Transverse Electromagnetic Gradiometer utilized with a mine beacon. Depicted in cross sectional view and not to scale, a mine tunnel 701 is depicted with an obstruction 703 such as a pile of rocks from a partial tunnel collapse or the like. The obstruction 703 prevents the miners 705 from exiting the mine, and is considered to be an extreme emergency. Unfortunately, after many mine collapses, there is no physical wiring in place to facilitate communication with the trapped miners (or the physical wire has been destroyed by the mine collapse), and of course conventional wireless radiofrequency communications is rendered inoperable underground. The present invention may thus include, in some embodiments of the present invention, a beacon 707 that generates an electromagnetic pulse of high power and low frequency such as a Marx generator, an explosively pumped flux compression generator, compulsators and their variants, and superconducting magnetic storage systems. The beacon 707 thus provides an electromagnetic signature that can be detected above ground by a plurality of transverse electromagnetic gradiometers 709, 71 1 , 713. More or fewer transverse electromagnetic gradiometers may be used to provide location coordinate information when the information from the plurality of transverse electromagnetic gradiometers is combined.

It is, therefore, apparent that there has been provided, in accordance with the various objects of the present invention, a Transverse Electromagnetic Gradiometer. While the various objects of this invention have been described in conjunction with preferred embodiments thereof, it is evident that many alternatives, modifications, and variations will be apparent to those skilled in the art. Accordingly, it is intended to embrace all such alternatives, modifications and variations that fall within the spirit and broad scope of the present invention as defined by this specification, claims and the attached drawings.

Claims

What is claimed is:

1 . An inductive vector electromagnetometer comprising:

a magnetically permeable core;

an induction coil wound upon the magnetically permeable core

an electrostatic shield comprising a conductive material and partially surrounding the induction coil wound upon the magnetically permeable core; and

a longitudinal slit in the electrostatic shield that generally runs the length of the electrostatic shield.

2. The inductive vector electromagnetometer of claim I , further comprising a signal connection electrically connected to the induction coil.

3. The inductive vector electromagnetometer of claim 1 , wherein the induction coil is tuned to detect frequencies in the range of from about three hertz to about three thousand hertz.

4. A transverse electromagnetic gradiometer comprising:

a first inductive vector electromagnetometer comprising:

a magnetically permeable core:

an induction coil wound upon the magnetically permeable core:

a longitudinal slit in the electrostatic shield that generally runs the length of the electrostatic shield;

a second inductive vector electromagnetometer comprising:

a magnetically permeable core;

an induction coil wound upon the magnetically permeable core;

a longitudinal slit in the electrostatic shield that generally runs the length of the electrostatic shield; a first amplifier having an input electrically connected to the first inductive vector electromagnetometer and an output electrically connected to a first low pass filter; a second amplifier having an input electrically connected to the second inductive vector electromagnetometer and an output electrically connected to a second low pass filter: a first analog to digital converter having an analog input electrically connected to the first low pass filter; and

a second analog to digital converter having an analog input electrically connected to the second low pass filter.

5. The transverse electromagnetic gradiometer of claim 4, further comprising a processor operative!y coupled to the first analog to digital converter.

6. The transverse electromagnetic gradiometer of claim 5, wherein the processor is a data acquisition processor.

7. The transverse electromagnetic gradiometer of claim 4, further comprising a processor operatively coupled to the second analog to digital converter.

8. The transverse electromagnetic gradiometer of claim 7, wherein the processor is a data acquisition processor.

9. The transverse electromagnetic gradiometer of claim 4, further comprising a processor operatively coupled to the first analog to digital converter and the second analog to digital converter.

10. The transverse electromagnetic gradiometer of claim 9, wherein the processor is a data acquisition processor.

1 1. The transverse electromagnetic gradiometer of claim 9, further comprising a communications and power supply module operatively coupled to the processor.

12. The transverse electromagnetic gradiometer of claim 1 1 , further comprising a computer operatively coupled to the communications and power supply module and an operator interface operatively coupled to the computer.

13. The transverse electromagnetic gradiometer of claim 12, further comprising a global positioning system (GPS) receiver operatively coupled to the computer.

14. A computer system programmed to receive and analyze harmonic signatures from a transverse electromagnetic gradiometer, the transverse electromagnetic gradiometer comprising:

a first inductive vector electromagnetometer comprising:

a magnetically permeable core:

an induction coil wound upon the magnetically permeable core;

a second inductive vector electromagnetometer comprising:

a magnetically permeable core:

an induction coil wound upon the magnetically permeable core:

a first amplifier having an input electrically connected to the first inductive vector electromagnetometer and an output electrically connected to a first low pass filter;

a second amplifier having an input electrically connected to the second inductive vector electromagnetometer and an output electrically connected to a second low pass filter; a first analog to digital converter having an analog input electrically connected to the first low pass filter; and

15. The computer system of claim 14, further comprising a collection of harmonic signatures stored on computer readable media for comparison with the harmonic signature received from the transverse electromagnetic gradiometer.

16. The computer system of claim 15, wherein the collection of harmonic signatures stored on computer readable media is organized by signature type.

17. The computer system of claim 14, further comprising a global positioning system (GPS) receiver configured to provide location information to the computer.

18. The computer system of claim 14, further comprising data from a global positioning system stored on computer readable media.

19. The computer system of claim 18, wherein the global positioning system data is correlated with harmonic signatures received from the transverse electromagnetic gradiometer.

20. The computer system of claim 14, further comprising a wireless connection between the computer and the transverse electromagnetic gradiometer.