Precision location methods and systems

• US 8,928,459 B2
• Filed: 06/13/2008
• Issued: 01/06/2015
• Est. Priority Date: 06/15/2007
• Status: Active Grant

• Current Assignee: Worcester Polytechnic Institute
• Original Assignee: Worcester Polytechnic Institute
• Inventors: Cyganski, David, Duckworth, R. James, Orr, John A., Michalson, William R.
• Primary Examiner(s): Bugg, George
• Assistant Examiner(s): OBINIYI, PAULSON IDOWU
• Application Number:
  US12/664,844
• Publication Number:
  US 20100277339A1
• Time in Patent Office: 2,398 Days
• Field of Search: 340/539.13, 340/539.15, 340/539.16, 340/539.17, 340/539.21, 340/539.22, 375/266, 375/267, 375/295
• US Class Current: 340/8.1
• CPC Class Codes: G01S 1/026 of associated receivers
• CPC Class Codes: G01S 2205/02 Indoor
• CPC Class Codes: G01S 5/02 using radio waves using satellite radio beacon systems for determining position G01S19/00

Abstract

Systems and methods are described herein for determining the location of a transmitter by jointly and collectively processing the full sampled signal data from a plurality of receivers to form a single solution.

Claims

1. A system for locating an object, comprising:

a transmitter for transmitting a location signal, x(t);

a plurality of repositionable receivers, where n is the number of receivers, for positioning about a region in which the transmitter is located, each repositionable receiver including a transceiver for receiving the location signal and for transmitting data representative of the received location signal, R_n(t), as it is received by the n^th respective receiver; and

a base station including a transceiver for receiving the representative data transmitted by at least a plurality of the repositionable receivers and a processor for collectively processing the representative data based on a plurality of potential transmitter locations, including reflector locations, to identify at least one of the potential transmitter locations as a likely transmitter location,

wherein said processor is configured to collectively process the representative data by;

creating a matrix of range rephased signals, R′

_n(t), for the plurality of location signals received at the respective repositionable receivers for each of the plurality of potential transmitter locations such that R′

_n(t)=R_n(t+{circumflex over (t)}_n), where {circumflex over (t)}_n is the signal delay expected if the transmitter were in fact located at a potential location; and

identifying at least one potential location of the plurality of potential locations as the likely transmitter location, based on the range rephased signals in the matrix being closest to frequency independent and therefore varying only by a complex scalar factor associated with each respective receiver.

2. The system of claim 1, wherein the base station processor processes the representative data using a matrix rank revealing process.

3. The system of claim 1, wherein the base station processor processes the representative data using a singular value decomposition process.

4. The system of claim 1, wherein the base station comprises a display for displaying the at least one identified position.

5. The system of claim 1, wherein identifying a likely transmitter location comprises identifying at least one potential location of the plurality of potential locations at which the signals received by the repositionable receivers are closest to differing by respective constant phase and amplitude factors.

6. The system of claim 1, wherein the representative data corresponding to a received signal comprises a Fourier domain representation of the received signal.

7. The system of claim 1, wherein the representative data corresponding to a received signal comprises samples of the received signal.

8. The system of claim 1, wherein the system further comprises a second transmitter for transmitting a second location signal.

9. The system of claim 8, wherein each repositionable receiver receives the second location signal, and distinguishes the location signal and the second location signal based upon a predetermined timing difference between the location signal and the second location signal, and wherein each repositionable receiver'"'"'s transceiver transmits data representative of the received location signal and the second location signal as they are received by the respective receiver.

10. The system of claim 8, wherein each repositionable receiver receives the second location signal, and distinguishes the location signal and the second location signal based upon a predetermined difference in frequencies of the location signal and the second location signal, and wherein each repositionable receiver'"'"'s transceiver transmits data representative of the received location signal and the second location signal as they are received by the respective receiver.

11. The system of claim 8, wherein each repositionable receiver receives the second location signal, and wherein each repositionable receiver'"'"'s transceiver transmits data representative of the received location signal and the second location signal as they are received by the respective receiver.

12. The system of claim 1, wherein the system further comprises a plurality of transmitters for transmitting a plurality of location signals.

19. The system of claim 3, wherein the processor identifies the likely transmitter location as that resulting in a largest singular value of a range rephased signal matrix among potential transmitter locations.

13. A method for locating objects, the method comprising the steps of:

transmitting a location signal, x(t), using a transmitter;

receiving the signal using a plurality of receivers positioned about the transmitter, where n is the number of receivers;

generating by each of the plurality of receivers signal data representing the signal, R_n(t), received by each of the n respective receivers;

transmitting by the plurality of receivers the signal data to a processor; and

receiving and collectively processing the signal data based on a plurality of potential transmitter locations, including reflector locations, to identify at least one of the potential transmitter locations as a likely transmitter location,

wherein processing the signal data comprises;

creating a matrix of range rephased signals, R′

_n(t), for the plurality of location signals received at the respective repositionable receivers for each of the plurality of potential transmitter locations such that R′

_n(t)=R_n(t+{circumflex over (t)}_n), where {circumflex over (t)}_n is the signal delay expected if the transmitter were in fact located at a potential location; and

identifying at least one potential location of the plurality of potential locations as the likely transmitter location, based on the range rephased signals in the matrix being closest to frequency independent and therefore varying only by a complex scalar factor associated with each respective receiver.

14. The method of claim 13, wherein processing the signal data comprises generating a matrix including the unification of the signal data from a plurality of the receivers;

and applying an iterative algorithm to the matrix.

15. The method of claim 13, wherein processing the signal data comprises applying a signal matrix rank revealing process.

16. The method of claim 13, wherein processing the signal data comprises applying a singular value decomposition to the signal data.

20. The method of claim 16, wherein processing the signal data comprises identifying the likely transmitter location as that resulting in a largest singular value of a range rephased signal matrix among potential transmitter locations.

17. A non-transitory computer readable medium encoding computer readable instructions, which, upon execution by a processor cause the processor to carry out a method comprising:

receiving signal data R_n(t) corresponding to a location signal received by each of a plurality of mobile receivers, wherein the location signal originated from a transmitter, and n is the number of the respective mobile receiver; and

collectively processing the signal data based on a plurality of potential transmitter locations, including reflector locations, to identify at least one of the potential transmitter locations as a likely transmitter location,

wherein processing the signal data comprises;

creating a matrix of range rephased signals, R′

_n(t), for the plurality of location signals received at the respective mobile receivers for each of the plurality of potential transmitter locations such that R′

_n(t)=R_n(t+{circumflex over (t)}_n), where {circumflex over (t)}_n is the signal delay expected if the transmitter were in fact located at a potential location; and

identifying at least one potential location of the plurality of potential locations as the likely transmitter location, based on the range rephased signals in the matrix being closest to frequency independent and therefore varying only by a complex scalar factor associated with each respective mobile receiver.

18. A system for locating an object, comprising:

a plurality of transmitters, where n is the number of transmitters, for positioning about a region in which a receiver is located, each mobile transmitter including a transceiver for transmitting a location signal x(t);

a mobile receiver for receiving the plurality of location signals; and

a processor for collectively processing data representative of signals R_n(t) received by the receiver from the n^th mobile transmitter based on a plurality of potential receiver locations to identify at least one of the potential receiver locations as a likely receiver location,

wherein said processor is configured to collectively process the representative data by;

creating a matrix of range rephased signals, R′

_n(t), for the plurality of location signals received from the respective transmitters for each of the plurality of potential receiver locations such that R′

_n(t)=R′

_n(t+{circumflex over (t)}_n), where {circumflex over (t)}_n is the signal delay expected if the receiver were in fact located at a potential location; and

identifying at least one potential location of the plurality of potential locations as the likely receiver location, based on the range rephased signals in the matrix being closest to frequency independent and therefore varying only by a complex scalar factor associated with each respective transmitter.