Single receiver GPS pointing vector sensing

• US 9,778,365 B2
• Filed: 08/16/2012
• Issued: 10/03/2017
• Est. Priority Date: 08/25/2011
• Status: Active Grant

• Current Assignee: BAE Systems Information and Electronic Systems Integration Incorporated (BAE Systems Plc)
• Original Assignee: BAE Systems Information and Electronic Systems Integration Incorporated (BAE Systems Plc)
• Inventors: Frey, Jr., Robert D.
• Primary Examiner(s): McGue, Frank J
• Application Number:
  US13/883,376
• Publication Number:
  US 20130328718A1
• Time in Patent Office: 1,874 Days
• Field of Search: 34235703, 1735703, 1635703
• CPC Class Codes: G01S 19/05 providing aiding data
• CPC Class Codes: G01S 19/22 Multipath-related issues
• CPC Class Codes: G01S 19/54 using carrier phase measurements; using long or short baseline interferometry

Abstract

A system and method of determining a pointing vector using two GPS antennas and a single GPS receiver is disclosed. Two stationary GPS antennas, with a separation preferably less than half of a wavelength (˜100 mm) may use a single receiver to determine the pointing vector of the system. Incorporation of a three axis angular rate measurement allows pointing determination during system rotation. Incorporation of three axis gyroscope system allows pointing determination while in motion. The system provides the ability to sense multipath and jamming. Also the system can potentially eliminate the impact and certainly alert the user that the measurement may not be reliable.

Claims

1. A system for determining the pointing direction of a system relative to an earth reference comprising:

at least two stationary GPS antennas configured to receive multiple satellite transmissions, wherein said antennas are separated from each other by a distance less than half a wavelength;

a summer whereby outputs of said at least two antennas are summed; and

a single GPS receiver having a pointing vector estimator and being configured to receive the summed output of said at least two GPS antennas to determine a pointing vector of said system from outputs of said antennas;

said pointing vector estimator being configured to derive an optimum solution for pointing vector from said summed output of said at least two GPS antennas and known satellite geometries,

wherein said outputs of said antennas are scaled by first and second sinusoidal waveforms with time varying gains and summed generating a carrier phase modulation that is measured using a standard GPS carrier phase tracking loop to determine phase modulation amplitudes that are dependent on orientation of a satellite; and

wherein said pointing vector is updated based on difference between a predicted carrier phase modulation and a measured carrier phase modulation resulting from the time varying gain used in the summation of the antenna signals.

2. The system of claim 1, further comprising a three axis gyroscope system configured to allow pointing determination while in motion.

3. The system of claim 1, wherein said pointing vector accuracy is measured based on comparison of said predicted carrier phase and said measured carrier phase.

4. The system of claim 1, wherein jamming and multipath is detected and mitigated based on comparison of said predicted carrier phase and said measured carrier phase with elimination of compromised satellite measurements from a solution.

5. The system of claim 1, wherein said pointing vector estimator is a Kalman estimator.

6. A method for determining the pointing direction of a system relative to an earth reference comprising:

receiving transmission of a satellite by utilizing at least two stationary GPS antennas, wherein said antennas are separated from each other by a distance less than half a wavelength;

scaling the output of said antennas by first and second sinusoidal waveforms with time varying gains and summing said scaled first and second sinusoidal waveforms;

determining a pointing vector by utilizing a single GPS receiver having a pointing vector estimator configured to derive an optimum solution for pointing vector from said summed output of said at least two GPS antennas and known satellite geometries; and

updating said pointing vector based on difference between a predicted carrier phase modulation and a measured carrier phase modulation resulting from the time varying gain used in the summation of the antenna signals.

7. The method of claim 6, further comprising determining said pointing vector while in motion by utilizing a three axis gyroscope system.

8. The method of claim 6, further comprising scaling with time varying gains and summing outputs of said antennas in order to generate a carrier phase modulation that is dependent on orientation of said satellite.

9. The method of claim 6, further comprising measuring of pointing accuracy based on comparison of said predicted carrier phase and said measured carrier phase.

10. The method of claim 6, further comprising detecting and mitigating jamming and multipath based on comparison of said predicted carrier phase and said measured carder phase with the elimination of compromised satellite measurements from a solution.

11. The method of claim 6, wherein said pointing vector estimator is a Kalman estimator.

12. A method for determining the pointing direction of a system relative to an earth reference comprising:

receiving transmission of a satellite by utilizing at least two stationary GPS antennas, summing said transmission wherein said antennas are separated from each other by a distance less than half a wavelength;

determining a pointing vector by utilizing a single GPS receiver from said summed transmission said single GPS receiver having a pointing vector estimator configured to derive an optimum solution for pointing vector from said summed transmission of said at least two GPS antennas and known satellite geometries;

determining said pointing vector with said pointing vector estimator while in motion by utilizing a three axis gyroscope system; and

scaling by first and second sinusoidal waveforms with time varying gains and summing outputs of said antennas in order to generate a carrier phase modulation that is dependent on, orientation of said satellite; and

updating said pointing vector based on a difference between a predicted carrier phase modulation and a measured carrier phase modulation resulting from the time varying gain used in the summation of the antenna signals.

13. The method of claim 12, further comprising measuring of pointing accuracy based on comparison of said predicted carrier phase and said measured carrier phase.

14. The method of claim 12, further comprising detecting and mitigating Jamming and multipath based on comparison of said predicted carrier phase and said measured carrier phase with the elimination of compromised satellite measurements from a solution.

15. The method of claim 12, wherein said pointing vector estimator is a Kalman estimator.