System and method of carrier-phase attitude determination

• US 6,441,779 B1
• Filed: 06/30/2000
• Issued: 08/27/2002
• Est. Priority Date: 07/02/1999
• Status: Expired due to Fees

• Current Assignee: Fleet Capital Corporation (Bank of America Corp.)
• Original Assignee: KVH Industries Incorporated
• Inventors: Paradis, Ronald, Bennett, Sidney M.
• Primary Examiner(s): Cuchlinski, Jr., William A.
• Assistant Examiner(s): To, Tuan C
• Application Number:
  US09/607,865
• Time in Patent Office: 788 Days
• Field of Search: 701/215, 701/214, 701/4, 701/3, 701/220, 701/221, 342/357.11, 342/357, 342/359, 342/174, 342/360, 342/365, 342/354, 434/112
• US Class Current: 342/357.36
• CPC Class Codes: G01S 19/54 using carrier phase measurements; using long or short baseline interferometry
• CPC Class Codes: G01S 5/0247 Determining attitude
• CPC Class Codes: H01Q 1/1257 using the received signal strength
• CPC Class Codes: H01Q 3/06 over a restricted angle

Abstract

A system and a method for determining a satellite antenna attitude are disclosed. Radio signals from a satellite, such as a GPS satellite, are received by a plurality of coupled antenna elements forming an antenna array. Local attitude values of the antenna array and/or the antenna elements with respect to a reference plane are determined using a shaft encoder or gyro, whereas a carrier-phase antenna attitude is determined from the received radio signals. The array and/or array elements are rotated over a predetermined angle and a correction value of the antenna attitude is determined from a time-averaged difference between the local attitude values and the carrier-phase attitude values.

Claims

1. A method of determining a satellite antenna attitude, comprising:

providing a plurality of coupled antenna elements having an attitude, the antenna elements receiving radio signals from a satellite,

changing an orientation of the plurality of coupled antenna elements with respect to a reference plane over a predetermined angle,

locally monitoring the orientation of the plurality of coupled antenna elements,

calculating a difference between the locally monitored orientation with respect to the reference plane and the attitude determined from the received satellite radio signals as a function of time;

computing a time average of the difference; and

correcting the attitude of the plurality of coupled antenna elements based on the time average.

2. The method of claim 1, wherein the orientation of the plurality of coupled antenna elements is locally monitored using at least one of an encoder, a shaft encoder and a gyro.

3. A system for determining a satellite antenna attitude, comprising:

a plurality of coupled antenna elements having an attitude and receiving radio signals from a satellite,

a receiver which receives antenna signals from the coupled antenna elements and determines a phase relationship between the radio signals received by the plurality of coupled antenna elements,

a local attitude monitoring device which monitors an orientation of the plurality of coupled antenna elements with respect to a reference plane, and

a processing device which receives from the local attitude monitoring device a first signal corresponding to the orientation of the plurality of coupled antenna elements with respect to the reference plane and which receives from the receiver a second signal corresponding to the phase relationship,

wherein a direction of the plurality of coupled antenna elements with respect to a position of the satellite is changed over a predetermined angle and a correction value of the attitude of the plurality of coupled antenna elements is determined from a time-averaged difference between the first and second signal.

4. The system of claim 3, further comprising drive means coupled to at least a portion of the plurality of coupled antenna elements and adapted to adjust the orientation of the plurality of coupled antenna elements with respect to the reference plane.

5. The system of claim 3, wherein the local attitude monitoring device is at least one gyro.

6. The system of claim 3, wherein the processing device includes a filter.

7. The system of claim 3, wherein the plurality of coupled antenna elements is mounted on a common platform, with the antenna elements having a common orientation with respect to one another, and wherein the orientation of the plurality of coupled antenna elements with respect to a reference plane is adjusted by adjusting the orientation of the common platform.

8. The system of claim 3, wherein the plurality of coupled antenna elements is mounted on a common platform, with the orientation of the antenna elements being individually adjustable, and wherein the orientation of the plurality of coupled antenna elements with respect to a reference plane is adjusted by adjusting the orientation of the individual antenna elements.

9. A system for determining a satellite antenna attitude, comprising:

a plurality of coupled antenna elements having an attitude and receiving radio signals from a satellite,

a receiver which receives antenna signals from the coupled antenna elements and determines a phase relationship between the radio signals received by the plurality of coupled antenna elements,

a local attitude monitoring device which monitors an orientation of the plurality of coupled antenna elements with respect to a reference plane, and

a processing device which receives from the local attitude monitoring device a first signal corresponding to the orientation of the plurality of coupled antenna elements with respect to the reference plane and which receives from the receiver a second signal corresponding to the phase relationship,

wherein a direction of the plurality of coupled antenna elements with respect to a position of the satellite is changed over a predetermined angle and a correction value of the attitude of the plurality of coupled antenna elements is determined from a averaged difference between the first and second signal,

wherein the local attitude monitoring device is at least one encoder.

10. The system of claim 9, wherein the encoder is a shaft encoder.

11. A method of determining a satellite antenna attitude, comprising:

providing a plurality of coupled antenna elements having an attitude, the antenna elements receiving radio signals from a satellite,

changing an orientation of the plurality of coupled antenna elements with respect to a reference plane over a predetermined angle,

locally monitoring the orientation of the plurality of coupled antenna elements,

calculating a difference between the locally monitored orientation with respect to the reference plane and the attitude determined from the received satellite radio signals as the orientation of the plurality of coupled antenna elements is changed;

computing an average of the difference; and

correcting the attitude of the plurality of coupled antenna elements based on the average.

12. The method of claim 11, wherein

the plurality of coupled antenna elements is mounted on a common platform, with the antenna elements having a common orientation with respect to one another, and

the orientation of the plurality of coupled antenna elements with respect to a reference plane is adjusted by adjusting the orientation of the common platform.

13. The method of claim 12, wherein the orientation of the plurality of coupled antenna elements is locally monitored using at least one of an encoder, a shaft encoder, and a gyro.

14. The method of claim 11, wherein the coupled antenna elements include a substantially linear array.

15. The method of claim 11, wherein the coupled antenna elements include a substantially two-dimensional array.

16. A method of determining a satellite antenna attitude, comprising:

providing a plurality of coupled antenna elements having an attitude, the antenna elements receiving radio signals from a satellite,

calculating an antenna attitude using a phase relationship of the radio signals received by the coupled antenna elements,

changing an orientation of at least two of the plurality of coupled antenna elements with respect to a reference plane over a predetermined angle in a synchronized manner,

calculating further antenna attitudes using the phase relationship of the radio signals received by the coupled antenna elements as the orientation of at least two of the plurality of coupled antenna elements is changed; and

computing an average of the antenna attitudes thus calculated.

17. The method of claim 16, wherein the changing of the orientation of at least two of the plurality of coupled antenna elements with respect to the reference plane over the predetermined angle comprises rotating at least two of the plurality of coupled antenna element about their respective axes of symmetry.

18. The method of claim 16, wherein the coupled antenna elements include a substantially linear array.

19. The method of claim 16, wherein the coupled antenna elements include a substantially two-dimensional array.

20. A system for determining a satellite antenna attitude, comprising:

a plurality of coupled antenna elements having an attitude and receiving radio signals from a satellite,

a receiver which receives antenna signals from the coupled antenna elements and determines a phase relationship between the radio signals received by the plurality of coupled antenna elements,

a local attitude monitoring device which monitors an orientation of the plurality of coupled antenna elements with respect to a reference plane, and

a processing device which receives from the local attitude monitoring device a first signal corresponding to the orientation of the plurality of coupled antenna elements with respect to the reference plane and which receives from the receiver a second signal corresponding to the phase relationship,

wherein a direction of the plurality of coupled antenna elements with respect to a position of the satellite is changed over a predetermined angle and a correction value of the attitude of the plurality of coupled antenna elements is determined from an averaged difference between the first and second signal.

21. The system of claim 20, wherein the coupled antenna elements include a substantially linear array.

22. The system of claim 20, wherein the coupled antenna elements include a substantially two-dimensional array.

23. The system of claim 20, wherein the plurality of coupled antenna elements is mounted on a common platform, with the antenna elements having a common orientation with respect to one another, and wherein the orientation of the plurality of coupled antenna elements with respect to a reference plane is adjusted by adjusting the orientation of the common platform.

24. The system of claim 23, wherein the local monitoring device is at least one of an encoder, a shaft encoder, and a gyro.

25. The system of claim 20, wherein the processing device includes a filter.

26. A system for determining a satellite antenna attitude, comprising:

a plurality of coupled antenna elements having an attitude and receiving radio signals from a satellite,

a receiver which receives antenna signals from the plurality of coupled antenna elements and determines a phase relationship between the radio signals received by at least two of the plurality of coupled antenna elements, and

a processing device which receives from the receiver a signal corresponding to the phase relationship and calculates an antenna attitude therefrom,

wherein an orientation of at least two of the plurality of coupled antenna elements with respect to a position of the satellite is changed over a predetermined angle in a synchronized manner and an attitude of the plurality of coupled antenna elements is determined from an average of the antenna attitudes calculated while the orientation is changed.

27. The system of claim 26, wherein the change in the orientation of at least two of the plurality of coupled antenna elements with respect to the position of the satellite comprises rotating at least two of the plurality of coupled antenna elements about their respective axes of symmetry.

28. The system of claim 26, wherein the coupled antenna elements include a substantially linear array.

29. The system of claim 26, wherein in the coupled antenna elements include a substantially two-dimensional array.