Beacon-based geolocation using a low frequency electromagnetic field

Patent metadata

Field	Value
Publication number	US-10048073-B2
Application number	US-201113290574-A
Country	US
Kind code	B2
Filing date	Nov 7, 2011
Priority date	Nov 7, 2011
Publication date	Aug 14, 2018
Grant date	Aug 14, 2018

Abstract

A method of performing geolocation of receivers, transmitters, and conductive objects includes detecting, with one or more receivers, magnetic field signals generated by one or more transmitters, with each transmitter including two or more co-located coils that are electrically unstable and unbalanced, and that have a mechanically stable orientation with respect to one another. The magnetic field signals from each of the two or more co-located coils of each of the two or more transmitters are decomposed into individual magnetic field components. A set of invariant scalar values that are independent of orientation of one or more magnetic antennas associated with the one or more receivers are calculated from the individual magnetic field components, and the position of an object is determined using the set of invariant scalar values.

First claim

The invention claimed is:

1. A method of performing geolocation of an object, the method comprising:
detecting, with one or more receivers, magnetic field signals generated by one or more transmitters, with each transmitter comprising two or more coils that are mechanically stable with respect to one another, are positioned around a same point and are electrically variable with respect to each other, wherein each of the two or more coils generates a signal with a different frequency than others of the two or more coils and the coils do not include a common controller, the frequencies being in the ultra-low frequency (ULF) or very-low frequency (VLF) range;
decomposing the magnetic field signals from each of the coils of each of the two or more transmitters into individual magnetic field components for each coil of each transmitter;
calculating, from the individual magnetic field components, a set of invariant scalar values that are independent of orientation of one or more magnetic antennas associated with the one or more receivers;
using the set of invariant scalar values, determining a geographic position of the object by:
determining a line of bearing (LOB) to each of the one or more transmitters based on an analysis of the set of invariant scalar values, the set of invariant scalar values being derived from a total, n, of magnetic field signals generated by the two or more coils of each of the one or more transmitters, and wherein n corresponds to, for each transmitter, the number of co-located coils;
determining, for a given transmitter, i, an LOB dependent plane, {circumflex over (n)} i , based on the magnetic field signals generated by the first and second coils in accordance with the expression:

n
^

i

=

B
ω

1
i

×

B
ω

2
i



B

ω
_

1
i

×

B

ω
_

2
i



;

wherein B 1 i and B 2 i are the magnetic fields, respectively, of the two coils of the first coil and second coil of the transmitter i;
wherein a given individual coil (k) is characterized by a single a geometrical parameter comprising its orientation, {circumflex over (m)} k ; and
wherein a given pair of coils (k, l) is characterized by a transmission plane orientation in accordance with the expression:

u
^

=

m
^

k

×

m
^

l



m
^

k

×

m
^

l



;

wherein {circumflex over (m)} k and {circumflex over (m)} l are unitary vectors roughly perpendicular to respective areas of the pair of coils (k, l); and
outputting a global positioning system location of the object to a user over an output display based on the determined geographic position of the object.

2. The method of claim 1 , further comprising correlating LOB, {circumflex over (r)} i , for the transmitter i, with transmission plane orientation, û i , for the first and second coils of the transmitter i in accordance with the expressions:

{

u
)

i

·

n
^

i

=

3
⁢

(

r
^

i

·

u
^

i

)

2

-
2

4
-

3
⁢

Assignees

• Dolgin Benjamin
• Davis Clayton
• Zellner James C
• Cotten Steven
• Raytheon Co

Inventors

• Dolgin Benjamin
• Davis Clayton
• Zellner James C
• Cotten Steven

Classifications

• G01V3/10 Primary

  using induction coils · CPC title

• G01C21/00 Primary

  Navigation; Navigational instruments not provided for in groups G01C1/00 - G01C19/00 (measuring distance traversed on the ground by a vehicle G01C22/00; control of position, course, altitude or attitude of vehicles G05D1/00; traffic control systems for road vehicles involving transmission of navigation instructions to the vehicle G08G1/0968) · CPC title