Systems and methods for a code carrier divergence high-pass filter monitor

• US 10,215,862 B2
• Filed: 04/07/2014
• Issued: 02/26/2019
• Est. Priority Date: 04/07/2014
• Status: Active Grant

• Current Assignee: Honeywell International Inc.
• Original Assignee: Honeywell International Inc.
• Inventors: Syrstad, Justin Joseph, Brenner, Mats Anders, Howard, John M., Class, Kim A., Johnson, Bruce G., Reuter, Randy J.
• Primary Examiner(s): Gregory, Bernarr E
• Assistant Examiner(s): Pervin, Nuzhat
• Application Number:
  US14/247,037
• Publication Number:
  US 20150285916A1
• Time in Patent Office: 1,786 Days
• Field of Search: 3423574
• CPC Class Codes: G01S 19/03 Cooperating elements; Interaction or communication between different cooperating elements or between cooperating elements and receivers
• CPC Class Codes: G01S 19/07 providing data for correcting measured positioning data, e.g. DGPS [differential GPS] or ionosphere corrections
• CPC Class Codes: G01S 19/08 providing integrity information, e.g. health of satellites or quality of ephemeris data

Abstract

Systems and methods for a code carrier divergence (CCD) high-pass filter monitor are provided. In one embodiment, a signal deformation monitor for a GNSS ground based augmentation station, the monitor comprising: a CCD monitor stage communicatively coupled to a plurality of GNSS reference receivers, wherein the CCD monitor stage inputs raw pseudorange code measurements and accumulated delta range carrier measurements from each of the plurality of GNSS reference receivers; and a Code Carrier Divergence -High Pass Filer (CCD-HPF) monitor stage communicatively coupled to the CCD monitor stage, wherein the CCD-HPF monitor processes each of a plurality of low-pass filtered divergence rate measurements, d₂produced by the CCD monitor stage through a high-pass filter to calculate an averaged CCD-HPF monitor divergence rate, d_{3_Average}; wherein the signal deformation monitor outputs an exclusion signal associated with a GNSS satellite when the averaged CCD-HPF monitor divergence rate, d_{3_Average}exceeds an exclusion threshold.

Claims

1. A global navigation satellite system (GNSS) ground based augmentation system (GBAS), the system comprising:

a plurality of global navigation satellite system (GNSS) reference receivers;

a processing unit coupled to a memory unit and the plurality of GNSS reference receivers, the processing unit implementing a signal deformation monitor comprising;

a Code Carrier Divergence (CCD) monitor stage; and

a Code Carrier Divergence-High Pass Filter (CCD-HPF) monitor stage;

wherein the CCD monitor stage inputs raw pseudorange code measurements and accumulated delta range carrier measurements from each of the plurality of GNSS reference receivers, the raw pseudorange code measurements and accumulated delta range carrier measurements associated with a navigation signal transmitted by a GNSS satellite;

wherein the CCD monitor stage outputs for each of the plurality of GNSS reference receivers respective low-pass filtered divergence rate measurements, d₂, for the GNSS satellite;

wherein the CCD-HPF monitor stage calculates for each of the plurality of GNSS reference receivers respective CCD-HPF divergence rate estimates, d₃, by applying a high pass filter algorithm to the respective low-pass filtered divergence rate measurements, d₂; and

wherein the CCD-HPF monitor stage calculates an averaged CCD-HPF monitor divergence rate, d_{3_Average} that is averaged across the plurality of GNSS reference receivers from the CCD-HPF divergence rate estimates, d₃, calculated for each of the plurality of GNSS reference receivers;

wherein based on comparing the d_{3_Average} to an exclusion threshold, the signal deformation monitor outputs an exclusion signal causing the GBAS to exclude using measurements from the navigation signal transmitted by the GNSS satellite to calculate pseudorange correction information.

2. The system of claim 1, wherein the CCD-HPF monitor stage outputs a monitor status flag, P_HPF,j associated with the GNSS satellite, wherein the signal deformation monitor outputs the exclusion signal based on the monitor status flag, P_HPF,j.

3. The system of claim 2, wherein the CCD-HPF monitor stage resets the monitor status flag, P_HPF,j associated with the GNSS satellite to permit inclusion of the GNSS satellite when the d_{3_Average} has decreased below a re-admittance threshold.

4. The system of claim 2, wherein the CCD-HPF monitor stage resets the monitor status flag, P_HPF,j associated with the GNSS satellite to permit inclusion of the GNSS satellite when the d_{3_Average} has decreased below a re-admittance threshold and the GNSS satellite has been excluded for at least a predetermine wait time.

5. The system of claim 1, wherein the exclusion threshold is dynamically determined as a function of detected broadband interference.

6. The system of claim 5, wherein the signal deformation monitor dynamically selects between a first exclusion threshold and a second exclusion threshold.

7. The system of claim 5, wherein the exclusion threshold is dynamically determined as a function of a number of GNSS reference receivers impacted by the broadband interference.

8. The system of claim 1, the CCD monitor stage comprising a plurality of linear time invariant filters, wherein the respective low-pass filtered divergence rate measurements, d₂ are calculated by the plurality of linear time invariant filters as a function of a difference between the raw pseudorange code measurements and accumulated delta range carrier measurements.

9. The system of claim 1, the CCD-HPF monitor stage comprising a high-pass filter, wherein the respective low-pass filtered divergence rate measurements, d₂ are filtered by the high-pass filter to derive the CCD-HPF divergence rate estimates, d₃.

10. The system of claim 9, wherein the high-pass filter comprises a second order, high-pass Butterworth filter.

11. The system of claim 9, wherein the high-pass filter has a cutoff frequency of 0.01 Hz.

12. A signal deformation monitor for a Global Navigation Satellite System (GNSS) ground based augmentation station, the monitor comprising:

a Code Carrier Divergence (CCD) monitor stage communicatively coupled to a plurality of GNSS reference receivers, wherein the CCD monitor stage inputs raw pseudorange code measurements and accumulated delta range carrier measurements from each of the plurality of GNSS reference receivers; and

a Code Carrier Divergence-High Pass Filter (CCD-HPF) monitor stage communicatively coupled to the CCD monitor stage, wherein the CCD-HPF monitor processes each of a plurality of low-pass filtered divergence rate measurements, d₂ produced by the CCD monitor stage through a high-pass filter to calculate an averaged CCD-HPF monitor divergence rate, d₃—

_Average, that is averaged across the plurality of GNSS reference receivers from CCD-HPF divergence rate estimates, d₃, calculated for each of the plurality of GNSS reference receivers;

wherein the CCD-HPF divergence rate estimates, d₃, are calculated by applying a high pass filter algorithm to the respective low-pass filtered divergence rate measurements, d₂;

wherein the signal deformation monitor outputs an exclusion signal associated with a GNSS satellite when the averaged CCD-HPF monitor divergence rate, d_{3_Average} exceeds an exclusion threshold.

13. The monitor of claim 12, wherein the CCD-HPF monitor stage outputs a monitor status flag, P_HPF,j associated with the GNSS satellite, wherein the signal deformation monitor outputs the exclusion signal based on the monitor status flag, P_HPF,j.

14. The monitor of claim 13, wherein the CCD-HPF monitor stage resets the monitor status flag, p_HPF,j associated with the GNSS satellite to permit inclusion of the GNSS satellite when the d_{3_Average} has decreased below a re-admittance threshold and the GNSS satellite has been excluded for at least a predetermine wait time.

15. The monitor of claim 12, wherein the exclusion threshold is dynamically determined as a function of detected broadband interference.

16. The monitor of claim 15, wherein the signal deformation monitor dynamically selects between a first exclusion threshold and a second exclusion threshold.

17. The monitor of claim 12, the CCD monitor stage comprising a plurality of linear time invariant filters, wherein the respective low-pass filtered divergence rate measurements, d₂ are calculated by the plurality of linear time invariant filters as a function of a difference between the raw pseudorange code measurements and accumulated delta range carrier measurements.

18. The monitor of claim 12, the CCD-HPF monitor stage comprising a high-pass filter, wherein the respective low-pass filtered divergence rate measurements, d₂ are filtered by the high-pass filter to derive the CCD-HPF divergence rate estimates, d₃.

19. The monitor of claim 18, wherein the high-pass filter comprises a second order, high-pass Butterworth filter.

20. The monitor of claim 18, wherein the high-pass filter has a cutoff frequency of 0.01 Hz.