Systems and methods for enhanced direction of arrival detection and calculation

Patent metadata

Field	Value
Publication number	US-11460531-B2
Application number	US-202016803096-A
Country	US
Kind code	B2
Filing date	Feb 27, 2020
Priority date	Feb 27, 2020
Publication date	Oct 4, 2022
Grant date	Oct 4, 2022

Abstract

A system for determining a direction of arrival for signals is provided. The system includes a non-uniform linear array including a plurality of antenna and configured to receive a wireless signal. The system is programmed to receive a plurality of normalized phase candidates for the direction of arrival of the received wireless signal. For each of the plurality of normalized phase candidates, the at least one processor is programmed to calculate a phase error, estimate a plurality of unwrapped measured phases based on the corresponding phase error, and calculate a likelihood based on the corresponding plurality of unwrapped measured phases. The at least one processor is further programmed to select a normalized phase candidate as a direction of arrival estimate based on a comparison of the plurality of likelihood normalized phases.

First claim

What is claimed is:

1. A system for determining a direction of arrival for signals, the system comprising:
a non-uniform linear array comprising a plurality of antenna and configured to receive a wireless signal; and
a computing device comprising at least one processor in communication with at least one memory device, wherein said at least one processor is programmed to:
receive a plurality of normalized phase candidates for the direction of arrival of the received wireless signal;
for each of the plurality of normalized phase candidates, calculate a phase error;
for each of the plurality of normalized phase candidates, estimate a corresponding unwrapped measured phase based on the corresponding phase error;
for each of the plurality of normalized phase candidates, calculate a maximized likelihood normalized phase based on the corresponding plurality of unwrapped measured phases; and
select a normalized phase candidate as a direction of arrival estimate based on a comparison of the plurality of maximized likelihood normalized phases.

2. The system in accordance with claim 1 , further comprising a phase measurement unit in communication with said non-uniform linear array and said computing device, wherein said phase measurement unit is configured to:
receive the wireless signal from each of the plurality of antenna of said non-uniform linear array;
calculate a plurality of phase shifts between the wireless signal at pairs of the plurality of antenna; and
transmit the plurality of phase shifts to said computing device.

3. The system in accordance with claim 2 , wherein said at least one processor is further programmed to generate the plurality of normalized phase candidates based on the plurality of phase shifts.

4. The system in accordance with claim 2 , wherein said phase measurement unit generates a number of phase shifts equal to one less than a number of the plurality of antenna in the non-uniform linear array, and wherein each antenna in the plurality of antenna is included in at least one phase shift of the plurality of phase shifts.

5. The system in accordance with claim 2 , wherein said at least one processor is further programmed to generate the plurality of normalized phase candidates based on at least one phase shift of the plurality of phase shifts, a distance between two antennas in said non-uniform linear array associated with the at least one phase shift, and a frequency of the wireless signal.

6. The system in accordance with claim 5 , wherein said at least one processor is further programmed to:
generate a set of normalized phase candidates for each phase shift; and
compare the phase errors associated with each set of normalized phase candidates.

7. The system in accordance with claim 1 , wherein said non-uniform linear array receives a first signal from a first source and a second signal from a second source, and wherein said at least one processor is further programmed to determine a first direction of arrival for the first signal and a second direction of arrival for the second signal.

8. The system in accordance with claim 1 , wherein said at least one processor is further programmed to transmit the direction of arrival to a client computer device.

9. The system in accordance with claim 1 , wherein the normalized phase candidate represents the angle between the direction of arrival estimate and an array vector of said non-uniform linear array.

10. A computing device for determining a direction of arrival for signals, the computing device comprising at least one processor in communication with at least one memory device, wherein said at least one processor is programmed to:
receive a plurality of normalized phase candidates for the direction of arrival of a received wireless signal, wherein the received wireless signal is received by a non-uniform linear array comprising a plurality of antenna;
for each of the plurality of normalized phase candidates, calculate a phase error;
for each of the plurality of normalized phase candidates, estimate a corresponding unwrapped measured phase based on the corresponding phase error;
for each of the plurality of normalized phase candidates, calculate a maximized likelihood normalized phase based on the corresponding plurality of unwrapped measured phases; and
select a normalized phase candidate as a direction of arrival estimate based on a comparison of the plurality of maximizes likelihood normalized phases.

11. The computing device in accordance with claim 10 , where said at least one processor is further programmed to receive a plurality of phase shifts from a phase measurement unit, wherein the phase measurement unit is in communication with the non-uniform linear array and is configured to:
receive the wireless signal from each of the plurality of antenna of the non-uniform linear array;
calculate the plurality of phase shifts between the wireless signal at pairs of the plurality of antenna; and
transmit the plurality of phase shifts to the computing device.

12. The computing device in accordance with claim 11 , wherein said at least one processor is further programmed to generate the plurality of normalized phase candidates based on the plurality of phase shifts.

13. The computing device in accordance with claim 11 , wherein the phase measurement unit is also configured to generate a number of phase shifts equal to one less than a number of the plurality of antenna in the non-uniform linear array, and wherein each antenna in the plurality of antenna is included in at least one phase shift of the plurality of phase shifts.

14. The computing device in accordance with claim 11 , wherein said at least one processor is further programmed to generate the plurality of normalized phase candidates based on at least one phase shift of the plurality of phase shifts, a distance between two antennas in the non-uniform linear array associated with the at least one phase shift, and a frequency of the wireless signal.

15. The computing device in accordance with claim 14 , wherein said at least one processor is further programmed to:
generate a set of normalized phase candidates for each phase shift; and
compare the phase errors associated with each set of normalized phase candidates.

16. The computing device in accordance with claim 10 , wherein the non-uniform linear array receives a first signal from a first source and a second signal from a second source, and wherein said at least one processor is further programmed to determine a first direction of arrival for the first signal and a second direction of arrival for the second signal.

17. The computing device in accordance with claim 10 , wherein said at least one processor is further programmed to transmit the direction of arrival to a client computer device.

18. The computing device in accordance with claim 10 , wherein the normalized phase candidate represents the angle between the direction of arrival estimate and an array vector of said non-uniform linear array.

19. A method for determining a direction of arrival for signals, the method implemented on a computing device including at least one processor in communication with at least one memory device, the method comprising:
receiving a plurality of normalized phase candidates for the direction of arrival of a received wireless signal, wherein the received wireless signal is received by a non-uniform linear array comprising a plurality of antenna;
for each of the plurality of normalized phase candidates, calculating a phase error;
for each of the plurality of

Assignees

• Boeing Co

Inventors

• Dougherty William Warfield

Classifications

• G01S3/46

  using antennas spaced apart and measuring phase or time difference between signals therefrom, i.e. path-difference systems · CPC title

• G01S3/10 Primary

  Means for reducing or compensating for quadrantal, site, or like errors · CPC title

• G01S3/06 Primary

  Means for increasing effective directivity, e.g. by combining signals having differently oriented directivity characteristics or by sharpening the envelope waveform of the signal derived from a rotating or oscillating beam antenna (comparing amplitude of signals having differently oriented directivity characteristics to determine direction G01S3/16, G01S3/28) · CPC title

• G01S3/48

  the waves arriving at the antennas being continuous or intermittent and the phase difference of signals derived therefrom being measured · CPC title

• G01S3/02

  using radio waves · CPC title