SYSTEM AND METHOD FOR CORRECTING GLOBAL NAVIGATION SATELLITE SYSTEM CARRIER PHASE MEASUREMENTS IN RECEIVERS HAVING CONTROLLED RECEPTION PATTERN ANTENNAS

• US 20110050497A1
• Filed: 08/26/2009
• Published: 03/03/2011
• Est. Priority Date: 08/26/2009
• Status: Active Grant

• Current Assignee: Raytheon Company (Rtx Corporation)
• Original Assignee: Raytheon Company (Rtx Corporation)
• Inventors: Sain, Partrick M., Hautzik, Andrew M., Maenpa, Jon E.
• Granted Patent: US 8,089,402 B2
• Time in Patent Office: Days
• US Class Current: 342/368
• CPC Class Codes: G01S 19/23 Testing, monitoring, correcting or calibrating of receiver elements
• CPC Class Codes: G01S 19/29 carrier including Doppler, related G01S19/246 takes precedence

Abstract

This invention discloses a method for enhancing a Global Navigation Satellite System (GNSS), such as Global Positioning System (GPS), location calculation by supplying carrier phase corrections within a GNSS receiver used with a multiple element Controlled Reception Pattern Antenna (CRPA) receiver. GNSS carrier phase measurements should be compensated for receiver hardware and directionally dependent antenna errors to obtain desired accuracies for high precision GNSS positioning applications. One technique successfully employed in Fixed Reception Pattern Antenna (FRPA) GPS sensors applies a simple directionally dependent set of correction factors to the measurement outputs. For the complex case of a GNSS receiver employing a CRPA and dynamic beam steering, however, the multiplicity of combinations of antenna element outputs makes the FRPA compensation technique impractical. Compensation of carrier phase measurements is a problem not addressed in previous GPS CRPA beam steering sensors.

Claims

1. An apparatus for calibrating a global navigation satellite system (GNSS) receiver for errors in carrier phase measurements of GNSS transmitter signals, the apparatus comprising:

a controlled reception pattern antenna (CRPA) comprising a plurality of receiving elements and configured to sense a plurality of signals from a GNSS transmitter;

a digital sampler circuit configured to convert the plurality of sensed GNSS signals to a plurality of sampled digital signals; and

a digital processor configured to;

access phase calibration correction data for at least some combinations of the plurality of receiving elements and a plurality of transmitter orientations with respect to the CRPA;

generate beam steering control data using a transmitter orientation with respect to the CRPA;

combine the phase calibration correction data specific to the transmitter orientation with respect to the CRPA and each of the plurality of receiving elements together with the beam steering control data to generate corrected beam steering control data;

generate a composite corrected digital signal by combining the sampled digital signals and the corrected beam steering control data; and

convert the composite corrected digital signal into a corrected GNSS carrier phase measurement.

2. The apparatus of claim 1, wherein the CRPA is further configured to sense the plurality of signals from a plurality of GNSS transmitters using one or more transmitter frequencies, and the digital processor is further configured to:

access phase calibration correction data for at least some combinations of the plurality of receiving elements, the plurality of transmitter orientations with respect to the CRPA, and the one or more transmitter frequencies;

generate a plurality of beam steering control data at each of the one or more transmitter frequencies for the respective plurality of GNSS transmitters using respective transmitter orientations with respect to the CRPA;

combine the phase calibration correction data specific to the transmitter orientations with respect to the CRPA, the transmitter frequency, and each of the plurality of receiving elements together with the plurality of beam steering control data at each of the one or more transmitter frequencies to generate a plurality of corrected beam steering control data at each of the one or more transmitter frequencies; and

generate a composite corrected digital signal for each of the plurality of GNSS transmitters at each of the one or more transmitter frequencies by combining the sampled digital signals and the plurality of corrected beam steering control data at each of the one or more transmitter frequencies.

3. The apparatus of claim 2, further comprising an orientation processor configured to determine the orientation of the transmitter with respect to the CRPA for each of the plurality of GNSS transmitters.

4. The apparatus of claim 2, wherein the apparatus is configured to perform in real time.

5. The apparatus of claim 2, wherein the GNSS is the Global Positioning System (GPS).

6. The apparatus of claim 2, wherein the CRPA has seven elements.

7. The apparatus of claim 2, wherein the apparatus is mounted on a static platform.

8. The apparatus of claim 2, wherein the apparatus is mounted on a dynamic platform.

9. The apparatus of claim 8, wherein the apparatus is mounted on an aircraft, ship, or land vehicle and wherein the apparatus determines the beam steering control data accounting for a variable attitude of the dynamic platform.

10. A method for calibrating a global navigation satellite system (GNSS) receiver for errors in carrier phase measurements of GNSS transmitter signals, the method comprising:

sensing a plurality of signals from a GNSS transmitter with a controlled reception pattern antenna (CRPA) comprising a plurality of receiving elements;

digitally sampling the sensed GNSS signals to produce a plurality of sampled digital signals;

accessing phase calibration correction data for at least some combinations of the plurality of receiving elements and a plurality of transmitter orientations with respect to the CRPA;

generating beam steering control data using a transmitter orientation with respect to the CRPA;

combining the phase calibration correction data specific to the transmitter orientation with respect to the CRPA and each of the plurality of receiving elements together with the beam steering control data to generate corrected beam steering control data;

generating a composite corrected digital signal by combining the sampled digital signals and the corrected beam steering control data;

converting the composite corrected digital signal into a corrected GNSS carrier phase measurement.

11. The method of claim 10, wherein the CRPA is further configured to sense the plurality of signals from a plurality of GNSS transmitters using one or more transmitter frequencies, wherein the method further comprises:

determining the transmitter orientation with respect to the CRPA for each of the plurality of GNSS transmitters;

accessing phase calibration correction data for at least some combinations of the plurality of receiving elements, the plurality of transmitter orientations with respect to the CRPA, and the one or more transmitter frequencies;

generating a plurality of beam steering control data at each of the one or more transmitter frequencies for the respective plurality of GNSS transmitters using the respective transmitter orientations with respect to the CRPA;

combining the phase calibration correction data specific to the transmitter orientations with respect to the CRPA, the transmitter frequency, and each of the plurality of receiving elements together with the plurality of beam steering control data at each of the one or more transmitter frequencies to generate a plurality of corrected beam steering control data at each of the one or more transmitter frequencies; and

generating a composite corrected digital signal for each of the plurality of GNSS transmitters at each of the one or more transmitter frequencies by combining the sampled digital signals and the plurality of corrected beam steering control data at each of the one or more transmitter frequencies.

12. The method of claim 11, wherein the steps are configured to be performed in real time.

13. The method of claim 11, wherein the determining the orientation of the transmitter with respect to the CRPA for each of the plurality of transmitters comprises accounting for a variable attitude of the CRPA mounted on a dynamic platform.

14. The method of claim 11, wherein the GNSS is the Global Positioning System (GPS).