System and method of compensating for micro-jump events

• US 8,248,300 B2
• Filed: 06/02/2010
• Issued: 08/21/2012
• Est. Priority Date: 06/02/2010
• Status: Active Grant

• Current Assignee: Honeywell International Inc.
• Original Assignee: Honeywell International Inc.
• Inventors: Vallot, Lawrence C., Buck, Timothy M
• Primary Examiner(s): Keith, Jack W
• Assistant Examiner(s): McGue, Frank J
• Application Number:
  US12/792,546
• Publication Number:
  US 20110298661A1
• Time in Patent Office: 811 Days
• Field of Search: 342/357.62
• US Class Current: 342/357.62
• CPC Class Codes: G01S 19/26 involving a sensor measurement for aiding acquisition or tracking
• CPC Class Codes: G01S 19/30 code related G01S19/246 takes precedence
• CPC Class Codes: G01S 19/47 the supplementary measurement being an inertial measurement, e.g. tightly coupled inertial

Abstract

A system comprises a Global Navigation Satellite System (GNSS) receiver configured to acquire and track a unique radio frequency (RF) signal for each of a plurality of channels, wherein the GNSS receiver is configured to provide one or more system state measurements based on the unique RF signals; processing functionality configured to calculate a respective code delay error for each of the plurality of channels based on the respective unique RF signal; and micro jump detection functionality configured to calculate an average code delay error across all of the plurality of channels based on the plurality of calculated code delay errors, wherein the micro jump detection functionality is further configured to compare the calculated average code delay error to an error threshold to detect a micro jump event when the calculated average code delay error exceeds the error threshold.

Claims

1. A system comprising:

a Global Navigation Satellite System (GNSS) receiver configured to acquire and track a unique radio frequency (RF) signal for each of a plurality of channels, wherein the GNSS receiver is configured to provide one or more system state measurements based on the unique RF signals;

processing functionality configured to calculate a respective code delay error for each of the plurality of channels based on the respective unique RF signal; and

micro jump detection functionality configured to calculate an average code delay error across all of the plurality of channels based on the plurality of calculated code delay errors, wherein the micro jump detection functionality is further configured to compare the calculated average code delay error to an error threshold to detect a micro jump event when the calculated average code delay error exceeds the error threshold.

2. The system of claim 1, further comprising a display unit configured to display the system state measurements.

3. The system of claim 1, wherein the micro jump detection functionality is further configured to initiate one or more actions that mitigate effects of the detected micro jump event when the calculated average code delay error exceeds the error threshold.

4. The system of claim 3, wherein the micro jump detection functionality is further configured to initiate one or more actions that mitigate effects of the detected micro jump event when a signal is received from the GNSS receiver indicating a micro jump event has occurred.

5. The system of claim 3, further comprising:

an inertial navigation system (INS) configured to provide one or more system state measurements;

wherein the processing functionality is configured to control tracking each unique RF signal for each respective channel in the GNSS receiver based on the system states measurements provided by the GNSS receiver and by the INS to the processing functionality; and

wherein the processing functionality comprises a Kalman filter configured to calculate corrections to estimated system states based on measurements from the INS and the GNSS.

6. The system of claim 5, wherein the micro jump detection functionality is further configured to inject process noise covariance increments into a covariance model for clock states of the Kalman filter when the calculated average code delay error exceeds the error threshold.

7. The system of claim 5, wherein the micro jump detection functionality is further configured to disable carrier frequency error measurements when the calculated average code delay error exceeds the error threshold.

8. The system of claim 5, wherein the processing functionality is further configured to calculate a carrier power to noise density ratio (C/No) for each channel;

and

wherein the micro jump detection functionality is further configured to calculate an average C/No across all the channels and to release control of tracking the unique RF signal for each respective channel to the GNSS receiver when the average C/No is less than a noise threshold.

9. A method of compensating for a micro jump event, the method comprising:

calculating an average code delay error across a plurality of channels, each channel associated with a radio frequency (RF) signal being tracked by a Global Navigation Satellite System (GNSS) receiver, wherein each tracked RF signal contains a code sequence that is orthogonal to the code sequence of the other tracked RF signals;

comparing the calculated average code delay error to an error threshold to detect the micro jump event when the calculated average code delay error exceeds the error threshold; and

if the calculated average code delay error exceeds the error threshold, initiating one or more actions to mitigate effects of the detected micro jump event.

10. The method of claim 9, further comprising initiating the one or more actions to mitigate the effects of the detected micro jump event if a signal is received from the GNSS receiver indicating detection of the micro jump event.

11. The method of claim 9, further comprising:

calculating a time difference between a previous detected micro jump event and the current detected micro jump event if the calculated average code delay error exceeds the error threshold;

comparing the time difference to an event threshold; and

initiating the one or more actions to mitigate the effects of the detected micro-jump event only if the time difference exceeds the event threshold.

12. The method of claim 9, wherein initiating the one or more actions includes injecting process noise covariance increments into a covariance model for clock states of a Kalman filter.

13. The method of claim 12, further comprising disabling Kalman filter carrier frequency error measurements used in tracking the RF signals if the calculated average code delay error exceeds the error threshold.

14. The method of claim 9, further comprising

calculating an average carrier power to noise density ratio (C/No) across all of the plurality of channels;

comparing the calculated average C/No to a noise threshold; and

releasing control of tracking the RF signal for each respective channel back to the GNSS receiver when the average C/No across all of the plurality of channels is less than the noise threshold.

15. A program product comprising a processor-readable medium on which program instructions are embodied, wherein the program instructions are configured, when executed by at least one programmable processor, to cause the programmable processor to:

calculate an average code delay error across a plurality of channels, each channel associated with a radio frequency (RF) signal being tracked by a Global Navigation Satellite System (GNSS) receiver, wherein each tracked RF signal contains a code sequence that is orthogonal to the code sequence of the other tracked RF signals;

compare the calculated average code delay error to an error threshold to detect a micro jump event when the calculated average code delay error exceeds the error threshold; and

if the calculated average code delay error exceeds the error threshold, initiate one or more actions to mitigate effects of the detected micro jump event.

16. The program product of claim 15, wherein the program instructions are further configured to cause the programmable processor to:

initiate the one or more actions to mitigate the effects of the detected micro jump event if a signal is received from the GNSS receiver indicating detection of the micro-jump event.

17. The program product of claim 15, wherein the program instructions are further configured to cause the programmable processor to:

calculate a time difference between a previous detected micro jump event and the current detected micro jump event if the calculated average code delay error exceeds the error threshold;

compare the time difference to an event threshold; and

initiate the one or more actions to mitigate the effects of the detected micro jump event only if the time difference exceeds the event threshold.

18. The program product of claim 15, wherein the program instructions are further configured to cause the programmable processor to:

initiate the one or more actions by injecting process noise covariance increments into a covariance model for clock states of a Kalman filter.

19. The program product of claim 18, wherein the program instructions are further configured to cause the programmable processor to:

disable Kalman filter carrier frequency error measurement processing used in tracking the RF signals if the calculated average code delay error exceeds the error threshold.

20. The program product of claim 18, wherein the program instructions are further configured to cause the programmable processor to:

calculate an average carrier power to noise density ratio (C/No) across all of the plurality of channels;

compare the calculated average C/No to a noise threshold; and

release control of tracking the RF signal for each respective channel back to the GNSS receiver when the average C/No is less than the noise threshold.