INDUCTIVE COMMUNICATION SYSTEM

• US 3,660,760 A
• Filed: 07/23/1969
• Issued: 05/02/1972
• Est. Priority Date: 07/23/1969
• Status: Expired due to Term

• Current Assignee: Inductive Technology Incorporated X/O Alvin Edelman
• Original Assignee: Howard A. Schaad, Richard L. Randolph
• Inventors: Randolph, Richard L., Schaad, Howard A.
• Primary Examiner(s): Safourek, Benedict V.
• Application Number:
  US04/844,047
• Time in Patent Office: 1,014 Days
• Field of Search: 325/28,180,318,319,370 340/4,4E,15,15.5 324/1,5,6,7,8,9 179/82,1UW 343/709,719 385/382,385,377
• US Class Current: 455/41.1
• CPC Class Codes: H04B 13/02 Transmission systems in which the medium consists of the earth or a large mass of water thereon, e.g. earth telegraphy

Abstract

There is disclosed a communication system in which a pair of spaced conductor rods or elements, embedded or placed in the earth, and energized by a signal voltage to induce a dynamic magnetic signaling field above the earth surface between the conductor element and having a specific and relatively large controlled area of high signal resolution. A match of the earth'"'"''"'"'s impedance to the signal source is achieved by adding additional conductors at the remote conductor point. In locations where it may not be practical to embed the elements in a vertical position, horizontally buried elements may be used and the conductor nearest the signal voltage source may be constituted by an earth-embedded utility pipe. Switching devices controlled by coded signals may be used to connect or disconnect such conductors to thereby vary the system impedance or control the strength of the magnetic induction signaling field, as well as vary the area and shape of the magnetic induction signaling field. The magnetic induction signaling field may be picked up by magnetic pick-up coil or other devices sensitive to magnetic fields.

Claims

1. A communication method comprising, establishing a magnetic induction signaling field above and contiguous to and essentially within a selected geometrical pattern on the eArth'"'"''"'"'s surface comprising the steps of:

providing a pair of conductor points spaced apart a distance less than the length of the selected geometrical pattern and defining the shape thereof, one of said provided conductor points being constituted by alternating current electrical ground, and the other of said provided conductor points being constituted by at least one conductor element embedded in the earth in such manner that any conductive shunting of capacitive characteristics of the earth media between said points is kept to a minimum, providing a signal voltage source, connecting said signal voltage source to said conductor points to thereby impress on the earth between said one or more conductor elements a sustained dynamic electrostatic field, and electrostatically induce, along the equipotential lines of said electrostatic field, current flow and create a dynamic magnetic induction signal field which extends above the earth'"'"''"'"'s surface and which is confined essentially within said selected geometrical area, and, inductively detecting said magnetic induction signaling field at a plurality of locations in said geometrical area.

2. The invention defined in claim 1 wherein said at least one conductor element is a straight rod of non-corrosive metal and said method including the step of lowering the system'"'"''"'"'s impedance at the embedded conductor element which is remote from said signal voltage source to enhance the capacitive current flow by inserting at least one additional conductor element in the earth.

3. The invention defined in claim 1 wherein including the step of embedding said at least one conductor element so that it is vertically embedded in the earth.

4. The invention defined in claim 2 wherein the step of lowering the impedance includes placing in the earth a horizontal conductor element adjacent to said at least one conductor element and connecting one end of said horizontal conductor element to an end of said at least one conductor element.

5. The invention defined in claim 2 wherein said at least one further conductor element is connected to said at least one conductor element by an electrical switch and including the step of selectively actuating said switch to selectively vary the size of said magnetic induction signaling field.

6. The invention defined in claim 1 wherein there are at least one further of said conductor points, including a further conductor element embedded essentially vertically in the earth, said one of said conductor points constituted by alternating current electrical ground being located at a first point adjacent to said signal voltage source, a second of said conductor points being located at a second point remote from said signal voltage source, and said further of said conductor points being located at a third point remote from said first and said second points, and said first conductor point being connected to a first output terminal of said signal voltage source, and low resistance conductor wire and switch means connecting said second and said third straight conductor points to the other output terminal, said method including the step of changing the shape of said geometrical pattern by operating said switch means to selectively apply said signal voltage to said second and/or said third straight conductor points.

7. The invention defined in claim 6 wherein said third conductor point is nearer to said first point than is said second point and located laterally of an imaginary line between said first point and said second point, and wherein the conductor wire-switch means connecting said third point to said other terminal has an effective resistance greater than the resistance between said other terminal and said second conductor element whereby sustained dynamic electrostatic fields are created in the earth between said first point and said second point and said first point and said third point to establish a pair of respectively symmetrical magnetic induction signal areas aBove the earth'"'"''"'"'s surface.

8. The invention defined in claim 7 including the step of adjusting the system'"'"''"'"'s total impedance at each of said remote points, respectively, by placing a further conductor element in the earth adjacent said remote points, respectively, and connecting one end thereof to an end of the conductor elements at said remote points, respectively.

9. A method of transmitting communication signals to points within a limited geographic land area comprising the steps of:

selecting at least a pair of spaced points within said limited geographical land area and defining one of said selected points being constituted by alternating current electrical ground, and the other of said points being constituted by at least one conductor element embedded in the earth in such manner that any conductive shunting of capacitive characteristics of the earth media between said points is kept to a minimum, impressing a signal voltage between said two spaced points and the large dielectric earth mass therebetween to impress an electrostatic signal field within said dielectric earth mass to thereby induce a large, homogenous magnetic signal field within and extending above the earth'"'"''"'"'s surface and for substantial lateral distances to each side of imaginary lines between said points, and within said limited geographical area, said land area being determined by the placement of said points on the earth'"'"''"'"'s surface, detecting by magnetic induction, changes in said magnetic signal field within said limited geographical land area to produce an electrical signal, and supplying said electrical signal to a utilization device.

10. The invention defined in claim 9 including extending the area of communication comprising, detecting the signal at a point within the area of communication established by impressing said signal voltage on said spaced points, amplifying the detected signal to produce a further signal voltage, impressing said further signal voltage on a further pair of spaced earth embedded conductor elements, detecting the resulting magnetic induction signaling field to produce a detected signal voltage, and applying said detected signal voltage to a utilization device.

11. The method of causing a thing protruding from the earth, such as a tree, building structure, or other thing having a portion embedded in the earth, to serve as a magnetic communication element comprising, embedding a pair of spaced conductor elements in the earth at each side of the thing, so that at least a portion of the thing is in the dielectric earth media between said spaced conductor elements and in the electrostatic field defined hereafter, said conductor elements being placed in the earth at each side of said thing, respectively, in such manner that any conductive shunting of capacitive characteristics of the earth media therebetween is kept to a minimum, and, applying a signal voltage to said pair of conductor elements to create a sustained dynamic electrostatic field in the earth between said conductor elements and at least the portion of said thing which is in the earth and said electrostatic field between said conductor elements.

12. The method of magnetic signaling within a building structure on and extending above the earth'"'"''"'"'s surface comprising the steps of vertically embedding at least one conductor element in the earth adjacent said building structure, said conductor element being placed in the earth in such manner that any conductive shunting of capacitive characteristics of the earth media and alternating current electrical ground is kept to a minimum, applying a signal voltage between said conductor element and alternating current electrical ground and electrostatically induce a flow of current in the earth at least along equipotential lines of said electrostatic field and create a dynamic magnetic induction field within and above the surface of the earth and extending within said building, INDUCTIVELY detecting said magnetic signaling field to produce an electrical signal, and applying said electrical signal to a utilization device.

13. A system for producing a dynamic magnetic signaling field above the earth'"'"''"'"'s surface and within a selected limited area thereof comprising, a source of electrical signal voltage having a pair of output terminals, a remote conductor member embedded into the earth and at a point remote from said signal voltage source, a near conductor member connected to the earth electrical ground at a point adjacent to said signal voltage source, said remote conductor member being embedded in the earth in such manner that any conductive shunting of capacitive characteristics of the earth media between said remote conductor member and said earth electrical ground is kept to a minimum, a conductor wire connecting said remote conductor member to one of said output terminals, and means connecting said near conductor member and said earth electrical ground to the other output terminal, whereby the earth between said conductor members is electrostatically energized by electrical signals from said signal voltage source and establishes a magnetic signaling field above and contiguous to the surface of the earth.

14. The invention defined in claim 13 including impedance reducing means at said remote conductor member for lowering the impedance as seen by said signal source, said impedance reducing means comprising at least one further conductor member buried in the earth and electrically connected to enhance the capacitive current flow in the earth therebetween.

15. The invention defined in claim 13 wherein said conductor connecting said remote conductor member to said source consists of a single wire.

16. The invention defined in claim 13 including at least one further remote conductor member, said at least one further remote conductor member being at a remote point nearer to said source than the first said remote conductor member, and a further conductor wire having an effective impedance higher than the impedance of the first said conductor wire and connected at one end to said first conductor member and intermediate said first conductor member and said source and connected at the other end to said further remote conductor member.

17. Apparatus for exciting the earth to establish a dynamic magnetic signaling field in the air over a selected geographical land area of the earth comprising, at least a pair of spaced conductor rods of substantially non-corrosive conductor material, said conductor rods being spaced a large distance apart and embedded in the earth to a distance of at least 2 feet, means connecting one of said conductor rods to alternating current electrical ground the other of said conductor rods being adopted to be placed in the earth in such manner that any conductive shunting of capacitive characteristics of the earth media between said rods is kept to a minimum, a signal voltage source adjacent to one of said conductor rods and having a pair of output terminals, low resistance conductor means connecting one of said output terminals to the earth embedded conductor rod adjacent thereto, and a low resistance wire conductor having an insulation thereon connecting the other of said output terminals to the other of said conductor rods, thereby an electrostatic field is impressed on the earth media to electrostatically induce displacement current flow and create a large homogenous magnetic signalling field.

18. The invention defined in claim 17 wherein said conductor rods are vertical and including at said other of said conductor rod means for lowering the impedance and enhancing capacitive current flow at said other conductor rod as seen at the end of said insulated low resistance wire conductor end connected to said other conductor rod.

19. The invention defined in claim 18 wherein said means for lowering the impedance comprises at leaSt one further conductor rod imbedded in the earth and connected at one end to an end of said other conductor rod.

20. The invention defined in claim 19 wherein said other vertical rod is of stainless steel and embedded in the earth for a distance of between 2 and 6 feet and wherein said horizontal conductor rod is at an angle of about 90 degrees to a line between said pair of spaced vertical conductor rods.

21. The invention defined in claim 20 wherein said horizontal conductor rod is between from about 3 to 9 feet in length and is buried in the earth at a depth of from about 6 to 12 inches.

22. The invention defined in claim 17 including means for extending the area of said magnetic signaling field, comprising wireless apparatus responsive to the signal between said spaced conductor rods for producing a signal voltage corresponding to the signal voltage from said signal voltage source, at least a further pair of spaced conductor rods embedded in the earth at points remote from said first named conductor rods, and means for connecting the signal voltage produced by said wireless apparatus to said at least further pair of spaced conductor rods.