Multiple Phase State Near-Field Electromagnetic System And Method For Communication And Location

• US 20090280742A1
• Filed: 02/23/2009
• Published: 11/12/2009
• Est. Priority Date: 02/25/2008
• Status: Active Grant

• Current Assignee: Q-Track Corporation
• Original Assignee: Q-Track Corporation
• Inventors: Compston, Andrew, DePierre, Robert, Schantz, Hans Gregory, Barron, James Matthew
• Granted Patent: US 8,253,626 B2
• Time in Patent Office: Days
• US Class Current: 455/41.100
• CPC Class Codes: H04B 5/02 using transceiver
• CPC Class Codes: H04B 5/48 Transceivers

Abstract

A multiple phase state near-field electromagnetic location and communication system includes a multiple phase state near-field transmitter, and a near-field locator receiver. The near-field transmitter is capable of operation in at least two states and each of these at least two states generates a state characteristic difference detected at the near-field locator receiver. The state characteristic difference may be employed for location determination, communication or both. The present invention is particularly well-suited for use in conjunction with a near-field electromagnetic ranging system. In further embodiments, a multiple phase state near-field electromagnetic location and communication process includes the steps of determining a transmission state for a near-field quadrature transmitter, transmitting a near-field transmission corresponding to said transmission state, receiving a near-field transmission corresponding to said transmission state, and determining a difference between at least two properties of said near-field transmission where the difference is characteristic of and corresponding to the transmission state.

Claims

1. A multiple phase state near-field electromagnetic system for information communications or location determination, comprising:

a multiple phase state near-field transmitter comprising multiple H-field antennas having non-parallel axes, said multiple phase state near-field quadrature transmitter capable of operation in at least two phase states, each of said two phase states characterized by said multiple H-field antennas being driven by signals of different relative phase from the relative phase of each other phase state; and

a near-field receiver,

said near field locator receiver receiving a difference between two signal properties from said near field transmitter for each phase state of said near field transmitter, said receiver using said differences between said two signal properties to determine said location or said information.

2. The multiple phase state near-field electromagnetic system described in claim 1 in which said difference between two signal properties is employed in a location determining process.

3. The multiple phase state near-field electromagnetic system described in claim 2 in which said location determining process involves a near-field electromagnetic ranging algorithm.

4. The multiple phase state near-field electromagnetic system described in claim 1 in which said difference between two signal properties is employed in a communication process.

5. The multiple phase state near-field electromagnetic system described in claim 1 in which said difference between two signal properties is employed in a location determining process and in a communication process.

6. The system of claim 1, wherein the transmitter generates said at least two phase states by driving two orthogonal H-field antennas in quadrature.

7. The system of claim 1, wherein the transmitter generates said at least two phase states by driving three H-field antennas with a three phase signal.

8. The system of claim 1, further including a vertical orientation sensor wherein the drive to the antennas reverses a direction of rotation of said at least two phase states upon detecting upside down orientation.

9. The system of claim 8, wherein the vertical orientation sensor is an accelerometer.

10. The system of claim 1, further including a database comprising predicted differences associated with locations;

wherein said location determination unit determines said location by finding a location in said database wherein said predicted differences correspond most closely with said differences determined by said difference unit.

11. The system of claim 1, further including a pattern generator for scheduling the transmission of a first state and a second state of said at least two phase states, wherein said pattern generator produces a non symmetrical pattern to distinguish said first state from said second state.

12. The system of claim 1, further including a pattern generator for scheduling the transmission of a first state and a second state of said at least two phase states, wherein said pattern generator produces a synchronizing pattern.

13. The system of claim 1, further including a second receiver receiving said signal sequence and determining a location for said transmitter, said second receiver and said first receiver communicating with a central computer and communicating said differences between said two signal properties to said central computer;

wherein said central computer determines said location based on said differences between said two signal properties from said first receiver and said second receiver for said first state and for said second state.

14. The system of claim 1, wherein the selection of a first state and a second state of said at least two phase states is determined by an information source and said receiver includes a demodulator to recover information from said signal sequence based on said received differences between said two signal properties for said first state and said second state.

15. A near field location system comprising:

a multiple phase state H-field transmitter transmitting a signal sequence comprising a multiple phase state signal in a first state for a first interval and in a second state for a second interval;

a near field receiver comprising an E-field receiver and at least one H-field receiver, the antennas of said at least one H-field and said E-field receiver aligned significantly perpendicular to one another;

a difference unit determining differences between at least two properties of said signal sequence as received by said near field receiver, said difference unit determining said differences corresponding to said first state and said second state; and

a location determination unit finding a location for said transmitter based on said differences corresponding to said first state and said second state.

16. The system of claim 15, wherein said differences determined by said difference unit comprise a difference between a phase from said E-field receiver and a phase from said at least one H-field receiver.

17. The system of claim 15, wherein said differences determined by said difference unit comprise a difference between an amplitude from said E-field receiver and an amplitude from said at least one H-field receiver.

18. The system as in claim 15, further including a second H-field receiver, said second H-field receiver having an antenna significantly perpendicular to the antenna of said first H-field receiver and said E-field receiver;

said difference measurement unit further measuring differences in properties between said E-field receiver and said second H-field receiver corresponding to said first state and corresponding to said second state;

said location determination unit finding a location for said transmitter based on said differences from either or both said H-field receivers and said E-field receiver corresponding to said first state and corresponding to said second state.

19. A system for communication of information using near field signal properties comprising:

a multiple phase state H-field transmitter transmitting a signal sequence comprising a multiple phase state signal in a first state for a first interval and in a second state for a second interval;

an information source coupled to said transmitter, said information source determining said first state and said second state in accordance with information from said information source;

a near field receiver comprising an E-field receiver and at least one H-field receiver, the antennas of said at least one H-field and said E-field receiver aligned significantly perpendicular to one another;

a difference unit determining differences between at least two properties of said signal sequence as received by said near field receiver, said difference unit determining said differences corresponding to said first state and said second state; and

a demodulator, said demodulator recovering said information based on said differences corresponding to said first state and said second state.

20. A method for determining a location of a transmitter, said method comprising:

transmitting a multiple phase state H-field signal sequence comprising a first state for a first interval and a second state for a second interval;

receiving said signal sequence with a near field receiver;

determining a first difference between two properties of said signal sequence corresponding to said first state and a second difference between two properties of said signal sequence corresponding to said second state; and

determining said location of said transmitter based on said first difference between said two properties and said second difference between said two properties.