Systems and methods for providing improved TCAS bearing measurement

• US 8,965,680 B2
• Filed: 02/25/2011
• Issued: 02/24/2015
• Est. Priority Date: 02/25/2011
• Status: Expired due to Fees

• Current Assignee: Honeywell International Inc.
• Original Assignee: Honeywell International Inc.
• Inventors: Wang, Guoqing, Xuan, Jianqiang
• Primary Examiner(s): Beaulieu, Yonel
• Application Number:
  US13/985,189
• Publication Number:
  US 20130325314A1
• Time in Patent Office: 1,460 Days
• Field of Search: 701/3, 701/10, 701/14, 701300-302, 342 73- 74, 342/82, 342/89, 342 29- 32, 343/700.R, 343/701, 343/705, 343/708
• US Class Current: 701/301
• CPC Class Codes: G01S 13/74 Systems using reradiation of radio waves, e.g. secondary radar systems; Analogous systems
• CPC Class Codes: G01S 13/933 of aircraft or spacecraft
• CPC Class Codes: G01S 3/48 the waves arriving at the antennas being continuous or intermittent and the phase difference of signals derived therefrom being measured
• CPC Class Codes: G08G 5/04 Anti-collision systems
• CPC Class Codes: H01Q 1/28 Adaptation for use in or on aircraft, missiles, satellites, or balloons
• CPC Class Codes: H01Q 21/20 the units being spaced along or adjacent to a curvilinear path slotted waveguide arrays H01Q21/005; circularly or helically slotted waveguides H01Q21/0062
• CPC Class Codes: H01Q 21/293 one unit or more being an array of identical aerial elements adaptive arrays H01Q3/2605
• CPC Class Codes: H01Q 3/267 Phased-array testing or checking devices

Abstract

Systems and methods for improving bearing accuracy in a Traffic Collision Avoidance System (TCAS) environment. An interrogation signal is transmitted from an array of antenna elements. A response to the transmitted interrogation signal from a target is received at a first pair of elements of the array. The first pair of elements is separated by at most ½λ of the response signal. A processor determines coarse bearing of the received response. A second pair of elements of the array of antenna elements receives a response to the interrogation signal. The second pair of elements is separated by approximately Nλ of the response signal. N is an integer not equal to zero. A first bearing value to the target is determined based on the determined coarse bearing and the received response at the second pair of elements. The array is mounted on an aircraft or on a ground installation.

Claims

1. A method for determining bearing in a traffic collision avoidance system, the method comprising:

transmitting a first interrogation signal from at least a portion of an array of antenna elements;

receiving, by at least a first pair of elements of the array of antenna elements, a first response to the transmitted first interrogation signal from a target, the at least first pair of elements being separated by at most one half of a wavelength (λ

) of a response signal;

determining, by a processor, a coarse bearing of the received first response;

receiving, by at least a second pair of elements of the array of antenna elements, a second response to the transmitted first interrogation signal, the at least second pair of elements being separated by approximately Nλ

of the response signal, N being an integer not equal to zero; and

determining, by the processor, a first bearing value for the target based on the coarse bearing and the received second response.

2. The method of claim 1, wherein the at least first pair of elements comprises two pair of elements, the two pair of elements sharing a common element, wherein axes linking elements in each of the two pair of elements are perpendicular to each other, and wherein the at least second pair of elements comprises a single pair of elements, one of the elements of the single pair of elements of the at least second pair of elements being the common element.

3. The method of claim 2, wherein all the pairs of elements of the array of antenna elements are located in approximately the same plane on an aircraft.

4. The method of claim 3, further comprising:

transmitting a second interrogation signal from a second array of antenna elements;

receiving, by at least a first pair of elements of the second array of antenna elements, a third response to the transmitted second interrogation signal from a target, the at least first pair of elements of the second array of antenna elements being separated by at most ½

λ

of the response signal;

determining, by the processor, a coarse bearing of the received third response;

receiving, by at least a second pair of elements of the second array of antenna elements, a fourth response to the transmitted second interrogation signal, the at least second pair of elements of the second array of antenna elements being separated by approximately Nλ

of the response signal, N being an integer not equal to zero;

determining, by the processor, a second bearing value for the target based on the coarse bearing associated with the received third response and the received fourth response; and

determining, by the processor, a third bearing value based on a phase difference derived from the second bearing value and a phase difference derived from the first bearing value.

5. The method of claim 4, wherein the at least first pair of elements of the second array of antenna elements comprises two pair of elements, the two pair of elements of the second array of antenna elements sharing a common element, wherein axes linking elements in each of the two pair of elements of the second array of antenna elements are perpendicular to each other, and wherein the at least second pair of elements of the second array of antenna elements comprises a pair of elements, one of the elements of the pair of elements of the at least second pair of elements of the second array of antenna elements being the common element.

6. The method of claim 5, wherein the pairs of elements of the at least first pair of elements of the second array of antenna elements and of the at least second pair of elements of the second array of antenna elements are located in approximately the same plane on an aircraft, wherein the first array of antenna elements is located on a top of the aircraft and the second array of antenna elements is located on a bottom of the aircraft.

7. The method of claim 1, wherein the at least first pair of elements of the array of antenna elements comprises two pair of elements being separated by at most ½

λ

of the response signal and wherein the at least second pair of elements of the array of antenna elements comprises two pair of elements being separated by approximately Nλ

of the response signal, N being an integer not equal to zero.

8. The method of claim 7, wherein the first and second pairs of elements of the array of antenna elements are located in the same plane.

9. The method of claim 8, wherein the first and second pairs of elements of the array of antenna elements are located on the ground and the second pair of elements surrounds the first pair of elements.

19. The method of claim 1, wherein the first response and the second response are determined based on a single response from the target.

20. The method of claim 4, wherein the first interrogation signal and the second interrogation signal are portions of a single interrogation signal.

10. A system comprising:

an array of antenna elements comprising at least a first pair of elements and at least a second pair of elements, the at least first pair of elements are separated by at most one half of a wavelength (λ

) of a response signal, the at least second pair of elements are separated by approximately Nλ

of the response signal, N being an integer not equal to zero;

a means for transmitting a first interrogation signal from at least a portion of the array of antenna elements;

a means for receiving a first response to the transmitted first interrogation signal from a target at the at least first pair of elements;

a processor configured to determine a coarse bearing of the received first response; and

a means for receiving a second response to the transmitted first interrogation signal at the at least second pair of elements,

wherein the processor is further configured to determine a first bearing value for the target based on the determined coarse bearing and the received second response.

11. The system of claim 10, wherein the at least first pair of elements comprises two pairs of elements, the two pairs of elements share a common element, wherein axes linking elements in each of the two pairs of elements are perpendicular to each other, and wherein the at least second pair of elements comprises a pair of elements, one of the elements of the pair of elements of the at least second pair of elements being the common element.

12. The system of claim 11, wherein all the pairs of the at least first pair of elements and the at least second pair of elements are located in approximately in the same plane on an aircraft.

13. The system of claim 12, further comprising:

a second array of antenna elements comprising at least a first pair of elements and at least a second pair of elements, the at least first pair of elements are separated by at most ½

λ

of a response signal, the at least second pair of elements are separated by approximately Nλ

of the response signal, N being an integer not equal to zero;

a means for transmitting a second interrogation signal from at least a portion of the second array of antenna elements;

a means for receiving a third response to the transmitted second interrogation signal from a target at the at least first pair of elements of the second array of antenna elements;

a means for receiving a fourth response to the transmitted second interrogation signal at the at least second pair of elements of the second array of antenna elements; and

a processor configured to;

determine a coarse bearing of the received third response;

determine a second bearing value for the target based on the determined coarse bearing associated with the second array of antenna elements and the received fourth response; and

determine a third bearing value based on a phase difference derived from the second bearing value and a phase difference derived from the first bearing value.

14. The system of claim 13, wherein the at least first pair of elements of the second array of antenna elements comprises two pairs of elements, the two pairs of elements of the second array of antenna elements share a common element, wherein axes linking elements in each of the two pairs of elements of the second array of antenna elements are perpendicular to each other, and wherein the at least second pair of elements of the second array of antenna elements comprises a pair of elements, one of the elements of the pair of elements of the at least second pair of elements being the common element.

15. The system of claim 14, wherein the pairs of elements of the at least first pair of elements of the second array of antenna elements and of the at least second pair of elements of the second array of antenna elements are located in approximately the same plane on an aircraft, wherein the first array of antenna elements is located on a top of the aircraft and the second array of antenna elements is located on a bottom of the aircraft.

16. The system of claim 10, wherein the at least first pair of elements of the array of antenna elements comprises two pairs of elements being separated by at most ½

λ

of the response signal and wherein the at least first pair of elements of the array of antenna elements comprises two pairs of elements being separated by approximately Nλ

of the response signal, N being an integer not equal to zero.

17. The system of claim 16, wherein the first and second pair of elements of the array of antenna elements are located in the same plane.

18. The system of claim 17, wherein the first and second pair of elements of the array of antenna elements are located on the ground.