Cycling reference multiplexing receiver system

• US 10,234,539 B2
• Filed: 12/16/2013
• Issued: 03/19/2019
• Est. Priority Date: 12/15/2012
• Status: Active Grant

• Current Assignee: Position Imaging, Inc.
• Original Assignee: Position Imaging, Inc.
• Inventors: Hill, Edward L., Schneider, Mark
• Primary Examiner(s): Galt, Cassi J
• Application Number:
  US14/649,576
• Publication Number:
  US 20150323643A1
• Time in Patent Office: 1,919 Days
• CPC Class Codes: G01S 5/02213 Receivers arranged in a network for determining the position of a transmitter
• CPC Class Codes: G01S 5/06 Position of source determined by co-ordinating a plurality of position lines defined by path-difference measurements G01S5/12 takes precedence
• CPC Class Codes: H04B 17/27 for locating or positioning the transmitter
• CPC Class Codes: H04B 7/0888 with selection

Abstract

A position tracking system for tracking a physical location of a radio frequency (RF) transmitter comprises at least four RF receiver antennae at known locations. Each receiver antenna receives RF signals from the RF transmitter. One receiver antenna is used as a reference antenna. A receiver channel unit is in communication with the RF receiver antennae. The receiver channel unit comprises a reference receiver channel and a measurement receiver channel. A multiplexer is dynamically configurable to selectively connect the reference receiver channel to the reference receiver antenna and to connect, in succession, each other receiver antenna to the measurement receiver channel. A comparator measures phase differences between the RF signals received by the reference antenna and those received by each other receiver antennae. A data processor computes the physical location of the RF transmitter from the phase differences measured by the comparator and the known locations of the receiver antennae.

Claims

1. A position tracking system for tracking a physical (x, y, z) position of a radio-frequency (RF) transmitter, the position tracking system comprising:

at least four RF receiver antennae disposed at known locations, each of the RF receiver antennae receiving RF signals from an RF transmitter, one of the at least four RF receiver antennae being used as a reference RF receiver antenna;

a receiver channel unit in communication with the at least four RF receiver antennae, the receiver channel unit comprising a plurality of receiver channels including a reference receiver channel and a measurement receiver channel, each RF receiver antenna of the at least four RF receiver antennae being in communication with the reference receiver channel and with the measurement receiver channel, the receiver channel unit further comprising a multiplexer dynamically configurable to selectively connect any one of the at least four RF receiver antennae to the reference receiver channel to be the reference RF receiver antenna, and to connect, in succession, each of the other RF receiver antennae of the at least four RF receiver antennae to the measurement receiver channel to be a measurement RF receiver antenna, the receiver channel unit further comprising a comparator circuit for measuring phase differences between the RF signals received by the reference RF receiver antenna and the RF signals received by each of the other RF receiver antennae when that other RF receiver antenna is currently the measurement RF receiver antenna; and

a data processor computing the physical (x, y, z) position of the RF transmitter from the phase differences measured by the comparator circuit and the known locations of the at least four RF receiver antennae, x, y, and z being spatial coordinates in three-dimensional space.

2. The position tracking system of claim 1, wherein the multiplexer is dynamically configurable to connect the reference receiver channel to a different one of the at least four RF receiver antennae, to select thereby a new reference RF receiver antenna.

3. The position tracking system of claim 1, wherein the multiplexer includes a first switching circuit and a second switching circuit, the first switching circuit being adapted to connect any one of the at least four RF receiver antennae to the measurement receiver channel, and the second switching circuit being adapted to connect any one of the at least four RF receiver antennae to the reference receiver channel.

4. The position tracking system of claim 3, wherein the data processor is in communication with the multiplexer to cause the first switching circuit to connect in succession each of the other RF receiver antennae of the at least four RF receiver antennae to the measurement receiver channel, while the second switching circuit connects the reference RF receiver antenna to the reference receiver channel.

5. The position tracking system of claim 1, wherein the data processor is in communication with the multiplexer to control which of the at least four RF receiver antennae the multiplexer connects to the reference receiver channel.

6. The position tracking system of claim 1, wherein the comparator circuit computes a time difference of arrival between RF signals received by the reference RF receiver antenna and RF signals received by each of the other RF receiver antennae based on the measured phase differences and forwards the time difference of arrival computations to the data processor for computation of the physical (x, y, z) position of the RF transmitter.

7. The position tracking system of claim 1, wherein the receiver channel unit comprises the data processor.

8. A radio-frequency (RF) receiver channel unit for tracking a physical (x, y, z) position of an RF transmitter, the RF receiver channel unit comprising:

a reference receiver channel including an RF receiver and demodulator, the reference receiver channel being in communication with at least four RF receiver antennae;

a measurement receiver channel including an RF receiver and demodulator, the measurement receiver channel being in communication with the at least four RF receiver antennae that are in communication with the reference receiver channel;

a multiplexer dynamically configurable to selectively connect any one of the at least four RF receiver antennae to the reference receiver channel to be a reference RF receiver antenna and to connect, in succession, each of the other RF receiver antennae of the at least four RF receiver antennae to the measurement receiver channel to be a measurement RF receiver antenna, wherein the RF receiver and demodulator of the reference receiver channel receives and demodulates RF signals transmitted by the RF transmitter and received by the reference RF receiver antenna, and wherein the RF receiver and demodulator of the measurement receiver channel, in succession, receives and demodulates RF signals transmitted by the RF transmitter and received by each of the other RF receiver antennae of the at least four RF receiver antennae when that other RF receiver antenna is currently the measurement RF receiver antenna; and

a comparator circuit measuring phase differences between the RF signals received by the reference RF receiver antenna and the RF signals received by each of the other RF receiver antennae when that other RF receiver antenna is currently the measurement RF receiver antenna.

9. The RF receiver channel unit of claim 8, further comprising a data processor computing the physical (x, y, z) position of the RF transmitter from the phase differences measured by the comparator circuit and known locations of the at least four RF receiver antennae, x, y, z being spatial coordinates in three-dimensional space.

10. The RF receiver channel unit of claim 8, wherein the multiplexer is dynamically configurable to connect the reference receiver channel to any of the other RF receiver antennae of the at least four RF receiver antennae, to select thereby a new reference RF receiver antenna.

11. The RF receiver channel unit of claim 9, wherein the multiplexer includes a first switching circuit and a second switching circuit, the first switching circuit being adapted to connect any one of the at least four RF receiver antennae to the measurement receiver channel, and the second switching circuit being adapted to connect any one of the at least four RF receiver antennae to the reference receiver channel.

12. The RF receiver channel unit of claim 11, wherein the data processor communicates with the multiplexer to cause the first switching circuit to connect, one at a time, each of the other RF receiver antennae of the at least four RF receiver antennae to the measurement receiver channel, while the second switching circuit connects the reference receiver antenna to the reference receiver channel.

13. The RF receiver channel unit of claim 9, wherein the data processor is in communication with the multiplexer to control which of the at least four RF receiver antennae the multiplexer connects to the reference receiver channel.

14. The RF receiver channel unit of claim 9, wherein the comparator circuit computes a time difference of arrival between the RF signals received by the reference RF receiver antenna and the RF signals received by each of the other RF receiver antennae of the at least four RF receiver antennae based on the measured phase differences and forwards the time difference of arrival computations to the data processor for computation of the physical (x, y, z) position of the RF transmitter.

15. A method for tracking a physical (x, y, z) position of a radio-frequency (RF) transmitter, the method comprising:

receiving RF signals from an RF transmitter by at least four RF receiver antennae that are disposed at known locations and are in communication with both a reference receiver channel and a measurement receiver channel;

dynamically selecting any one of the at least four RF receiver antennae as a reference RF receiver antenna;

connecting the selected reference RF receiver antenna to the reference receiver channel;

connecting, one at a time, each of the other RF receiver antennae of the at least four RF receiver antennae to the measurement receiver channel while connecting the selected reference RF receiver antenna to the reference receiver channel;

measuring phase differences between the RF signals received by the reference RF receiver antenna and the RF signals received by each of the other RF receiver antennae of the at least four RF receiver antennae; and

computing the physical (x, y, z) position of the RF transmitter from the measured phase differences and the known locations of the at least four RF receiver antennae, x, y, z being spatial coordinates in three-dimensional space.

16. The method of claim 15, further comprising dynamically selecting a new reference RF receiver antenna by disconnecting the selected reference RF receiver antenna from the reference receiver channel and connecting any of the other RF receiver antennae of the at least four RF receiver antennae to the reference receiver channel.

17. The method of claim 15, further comprising controlling a multiplexer to select which of the at least four RF receiver antennae connects to the reference receiver channel.

18. The method of claim 15, further comprising computing a time difference of arrival between the RF signals received by the reference RF receiver antenna and the RF signals received by each of the other RF receiver antennae based on the measured phase differences and forwarding the time difference of arrival computations to a data processor for computation of the physical (x, y, z) position of the RF transmitter.