Method and System for Calibrating Group Delay Errors in a Combined GPS and GLONASS Receiver

• US 20140062782A1
• Filed: 02/04/2013
• Published: 03/06/2014
• Est. Priority Date: 08/15/2008
• Status: Active Grant

• Current Assignee: Avago Technologies International Sales Pte Limited (Broadcom, Inc.)
• Original Assignee: Broadcom Corporation (Broadcom, Inc.)
• Inventors: ABRAHAM, Charles
• Granted Patent: US 9,261,600 B2
• Time in Patent Office: Days
• US Class Current: 342/357.73
• CPC Class Codes: G01S 19/23 Testing, monitoring, correcting or calibrating of receiver elements
• CPC Class Codes: G01S 19/235 Calibration of receiver components
• CPC Class Codes: G01S 19/33 Multimode operation in different systems which transmit time stamped messages, e.g. GPS/GLONASS

Abstract

A combined GPS and GLONASS receiver receives GPS signals and GLONASS signals. A calibration signal is generated utilizing the received GPS signals and/or the received GLONASS signals to offset group delay errors in the received GLONASS signals. The generated calibration signal is filtered through Kalman filters to estimate group delay variations in the received GLONASS signals. The estimated group error delay variations are combined with the received GLONASS signals to calibrate the received GLONASS signals by offsetting the estimated group error delay variations. When GPS signals are not available for use, the combined GPS and GLONASS receiver obtains group delay errors stored or in the received GLONASS signals to estimate calibration coefficients. The estimate calibration coefficients are updated utilizing received GPS and/or GLONASS signals. The updated estimated calibration coefficients are stored before turning off the combined GPS and GLONASS receiver to expedite calibrating of GLONASS signals received upon turning on.

Claims

1. A method for processing signals in a global navigation receiver, comprising:

receiving a first signal corresponding to a first satellite navigation system;

receiving a second signal corresponding to a second satellite navigation system;

generating a calibration signal using the first signal; and

reducing group delay errors in the second signal using the calibration signal.

2. The method of claim 1, further comprising:

filtering the calibration signal to generate a filtered calibration signal,

wherein reducing the group delay errors in the second signal comprises combining the filtered calibration signal with the second signal.

3. The method of claim 2, wherein the filtered calibration signal includes group delay variations associated with the second signal.

4. The method of claim 3, wherein reducing the group delay errors in the second signal further comprises offsetting the group delay errors in the second signal using the group delay variations associated with the second signal.

5. The method of claim 1, wherein the calibration signal includes calibration coefficients for offsetting the group delay errors.

6. The method of claim 1, wherein generating the calibration signal comprises:

generating first navigation information corresponding to the first satellite navigation system using the first signal;

converting the first navigation information to second navigation information corresponding to the second satellite navigation system;

calculating an estimate of the second signal using the second navigation information; and

comparing the second signal and the estimate of the second signal to generate the calibration signal.

7. The method of claim 1, wherein the first satellite navigation system corresponds to the Global Positioning System (GPS) and the second satellite navigation system corresponds to the Global Orbiting Navigation Satellite System (GLONASS).

8. The method of claim 1, wherein the first satellite navigation system corresponds to the Global Orbiting Navigation Satellite System (GLONASS) and the second satellite navigation system corresponds to the Global Positioning System (GPS).

9. A global navigation receiver, comprising:

a receiver front end configured to receive a first signal corresponding to a first satellite navigation system and a second signal corresponding to a second satellite navigation system;

a calibration signal generator configured to generate a calibration signal using the first signal; and

a signal calibrator configured to reduce group delay errors in the second signal using the calibration signal.

10. The global navigation receiver of claim 9, wherein the signal calibrator comprises:

a filter configured to filter the calibration signal to generate a filtered calibration signal; and

a signal coupler configured to combine the filtered calibration signal with the second signal to reduce the group delay errors in the second signal.

11. The global navigation receiver of claim 10, wherein the filtered calibration signal includes group delay variations associated with the second signal.

12. The global navigation receiver of claim 11, wherein the signal coupler is further configured to offset the group delay errors in the second signal using the group delay variations associated with the second signal.

13. The global navigation receiver of claim 9, wherein the calibration signal includes calibration coefficients for offsetting the group delay errors.

14. The global navigation receiver of claim 9, further comprising:

a navigation processor configured to generate first navigation information corresponding to the first satellite navigation system using the first signal,

wherein the calibration signal generator comprises;

a time transfer module configured to convert the first navigation information to second navigation information corresponding to the second satellite navigation system;

a signal estimator configured to calculate an estimate of the second signal using the second navigation information; and

a signal comparator configured to compare the second signal and the estimate of the second signal to generate the calibration signal.

15. The global navigation receiver of claim 9 wherein the first satellite navigation system corresponds to the Global Positioning System (GPS) and the second satellite navigation system corresponds to the Global Orbiting Navigation Satellite System (GLONASS).

16. The global navigation receiver of claim 9, wherein the first satellite navigation system corresponds to the Global Orbiting Navigation Satellite System (GLONASS) and the second satellite navigation system corresponds to the Global Positioning System (GPS).

17. A method for processing signals in a global navigation receiver, comprising:

receiving a first signal corresponding to a first satellite navigation system;

generating a calibration signal using the first signal; and

reducing group delay errors in the first signal using the calibration signal.

18. The method of claim 17, further comprising one or more of:

retrieving stored group delay variations associated with the first signal from memory; and

estimating group delay variations associated with the first signal using the first signal,

wherein reducing the group delay errors in the first signal further comprises offsetting the group delay errors in the first signal using at least one of the stored group delay variations and the estimated group delay variations.

19. The method of claim 18, further comprising:

receiving a second signal corresponding to a second satellite navigation system; and

updating the estimated group delay variations using the second signal.

20. The method of claim 19, wherein the first satellite navigation system corresponds to the Global Orbiting Navigation Satellite System (GLONASS) and the second satellite navigation system corresponds to the Global Positioning System (GPS).