TCAS bearing measurement receiver apparatus with phase error compensation method

• US 6,169,519 B1
• Filed: 09/21/1999
• Issued: 01/02/2001
• Est. Priority Date: 09/21/1999
• Status: Expired due to Term

• Current Assignee: Rockwell Collins, Inc. (Raytheon Technologies Corporation d/b/a RTX)
• Original Assignee: Rockwell Collins, Inc. (Raytheon Technologies Corporation d/b/a RTX)
• Inventors: Kyriakos, Constantinos S., Wahab, Sami R., Holecek, Charles L.
• Primary Examiner(s): Tarcza, Thomas H.
• Assistant Examiner(s): PHAN, DAO LINDA
• Application Number:
  US09/399,677
• Time in Patent Office: 469 Days
• Field of Search: 342/463, 342/465, 342/442, 342/445, 342/444
• US Class Current: 342/442
• CPC Class Codes: G01S 13/933 of aircraft or spacecraft
• CPC Class Codes: G01S 3/023 Monitoring or calibrating
• CPC Class Codes: G01S 7/2886 using I/Q processing

Abstract

A TCAS receiver, including a relative bearing measurement radio receiving apparatus for use with an antenna array having four antennas where each antenna has associated with it, its own receiver capable of demodulating both I and Q components of transmissions from an intruding aircraft.

Claims

1. A receiver system for use in determining the relative bearing between a protected position and an intruding aircraft, the system comprising:

an array of at least four antenna elements arranged around a circumference of a predetermined area, where each antenna element is for receiving transponder signals transmitted from a transponder located on an intruding aircraft;

a group of at least four receivers, where each receiver of said group is coupled to one of said antenna elements; and

,

a network of at least four phase detectors where each phase detector is exclusively coupled to and comparing outputs from a pair of said receivers.

2. A receiver of claim 1 wherein each of said receivers demodulates both the in-phase and quadrature components of said transponder signals.

3. A receiver of claim 2 wherein each of said receivers is coupled to a group of one or more antenna elements which is exclusive of antenna elements coupled to another of said receivers.

4. A receiver system of claim 3 wherein said array is diamond shaped.

5. A receiver system of claim 4 wherein said array further having axes connecting the at least four antenna elements which are orthogonal.

6. A receiver of claim 5 wherein said axes have non-equal dimensions.

7. A receiver of claim 2 further including a calibration signal source.

8. A receiver of claim 7 wherein said calibration signal source is a switchable TCAS transmitter.

9. A receiver of claim 6 further including a calibration signal source.

10. A receiver of claim 9 wherein said calibration signal source is a switchable TCAS transmitter.

11. A receiver system for use in determining the relative bearing between a protected position and an intruding aircraft, the system comprising:

first antenna means for capturing transponder signals transmitted from a transponder on an intruding aircraft;

second antenna means for capturing transponder signals transmitted from a transponder on an intruding aircraft;

third antenna means for capturing transponder signals transmitted from a transponder on an intruding aircraft;

fourth antenna means for capturing transponder signals transmitted from a transponder on an intruding aircraft;

said first antenna means, said second antenna means, said third antenna means, and said fourth antenna means arranged in a predetermined pattern, so that a phase difference will appear across at least two of said antenna means when receiving a transponder transmission;

first receiver means for processing signals captured by one of said antenna means;

second receiver means for processing signals captured by another of said antenna means;

third receiver means for processing signals captured by another of said antenna means;

fourth receiver means for processing signals captured by another of said antenna means; and

,

means for detecting phase differences in signals output by said first, second, third and fourth receiver means;

wherein said first receiver means, said second receiver means, said third receiver means, and said fourth receiver means, each demodulate both an in-phase and quadrature component of said signal captured by one of said antenna means.

12. A receiver system of claim 11 wherein said predetermined pattern of said first, second, third, and fourth antenna means is a diamond-shaped array wherein axes connecting pairs of said antenna means are orthogonal and said axes have unequal dimensions.

13. A receiver system of claim 11 further including a means for generating a calibration signal.

14. A receiver system of claim 13 wherein said means for generating a calibration signal is a switchable TCAS transmitter.

15. A receiver system of claim 12 further including a means for generating a calibration signal.

16. A receiver system of claim 15 wherein said means for generating a calibration signal is a switchable TCAS transmitter.

17. A receiver system of claim 11 wherein said first, second, third, and fourth antenna means are arranged in a rectangular configuration.

18. A receiver system of claim 17 wherein said rectangular configuration is square.

19. A method of compensation for phase errors in a TCAS receiver comprising the steps of:

providing a receiver having four antenna elements and four receivers, one for each antenna, wherein each receiver demodulates both I and Q components of received signals;

transmitting a calibration signal from a fourth of said antenna elements to first and second elements;

recording a first output of a phase detector across said first and second antenna elements;

switching the transmitting of said calibration signal from the first and second antenna elements to a third element;

recording a second output of said phase detector;

determining an average of said first and said second outputs;

using said average for a phase reference point of signals on said second antenna.