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Wide Area Augmentation System (WAAS) Operations Team AJW-1921

Offline Monitoring. Wide Area Augmentation System (WAAS) Operations Team AJW-1921. WIPP. B. J. Potter Brad Dworak Chad Sherrell August 9, 2010. Introduction. This presentation covers the 2 nd Quarter of 2010 (2010-04-01 – 2010-06-30)

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Wide Area Augmentation System (WAAS) Operations Team AJW-1921

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  1. Offline Monitoring Wide Area Augmentation System (WAAS) Operations TeamAJW-1921 WIPP B. J. Potter Brad Dworak Chad Sherrell August 9, 2010

  2. Introduction • This presentation covers the 2nd Quarter of 2010 • (2010-04-01 – 2010-06-30) • The week of May 2-8, 2010 was used for some of the detailed analysis • Enhancements • CCC and SQM Using HMI Tools • HMI Tool Build 299 • Using 66 days of data from the 2nd Quarter of 2010 • Next Steps • Add antenna offsets over time for launched or transitioned satellites • Migrate ephemeris database to oracle. • Analyze data for entire quarter

  3. Clock Runoff Assertion The a priori probability of a GPS satellite failure resulting in a rapid change in the GPS clock correction is less than 1.0x10-4 per satellite. Monitoring Approach Events typically result in a fast correction that exceeds 256 meters When this occurs, the satellite is set Do Not Use until the correction reaches a reasonable size Events where the satellite is set Do Not Use from excessively large fast corrections while the satellite is healthy are recorded

  4. Clock Runoff No Clock Runoff Events between 2010-04-01 and 2010-06-31

  5. Ephemeris • Assertion The CDF of GPS ephemeris errors in a Height, Cross-track, and Along-track (HCL) coordinate system is bounded by the CDF of a zero-mean Gaussian distribution along each axis whose standard deviations are osp-ephh, osp-ephc, and osp-ephl.The probability that a satellite’s position error is not characterized by this a priori ephemeris model is less than 10-4 per hour. • Monitoring Approach • Compare broadcast vs precise in HCL to ensure sigmas are less than 1m, 2.5m, 7.5m for Radial, Cross Track, and In Track

  6. Ephemeris – Radial PRN: 32 2010-04-17 18:45 2.90620465547 PRN: 12 2010-05-19 22:45 3.15903271889 PRN: 13 2010-06-23 10:45 3.47082223633 PRN: 04 2010-04-14 06:45 2.57121526929 PRN: 10 2010-05-07 06:45 2.03383879461 PRN: 26 2010-06-24 06:45 2.47104286788 PRN: 13 2010-04-27 20:00:00 -2.18794516163 PRN: 19 2010-05-20 02:45 -3.95543569803 PRN: 14 2010-06-29 10:45 -6.15598865905

  7. Ephemeris – In Track PRN: 24 2010-04-18 09:15 10.5221633747 PRN: 24 2010-04-23 07:30 10.026751596 PRN: 27 2010-06-14 01:15 9.60096455503 PRN: 27 2010-06-08 01:30 8.36316063262 PRN: 27 2010-04-22 23:15 -8.29359861274 PRN: 26 2010-06-24 06:45 -9.7607136513 PRN: 19 2010-05-20 02:45 -11.9114632839

  8. Ephemeris – Cross Track

  9. RIC Outliers

  10. Ionospheric Threat Model Monitoring • Assertion The values of and iono adequately protect against worst case undersampled ionosphere over the life of any ionospheric correction message, when the storm detectors have not tripped. • Monitoring Approach • Monitor for Chi^2 values greater than 1 in the four regions • CONUS > 1% • Alaska > 2% • Caribbean > 10% • Other > 3%

  11. Monitoring Regions

  12. MAX 2010-05-02 23:59:27

  13. MAX 2010-04-12 23:48:12

  14. MAX 2010-04-05 23:55:55 MAX 2010-04-12 23:50:55

  15. Daily Max Count by Region • Chi2 Threshold of 1.0 For Analysis (Chi2 Trips at 2.5) • CONUS • C&V: ZDC • Max Over Threshold: 55 • Date: 2010-04-12 23:48:12 • ALASKA • C&V: ZLA • Max Over Threshold : 229 • Date: 2010-05-02 23:59:27 • CARRIB • C&V: ZTL • Max Over Threshold : 949 • Date: 2010-04-05 23:55:55 • OTHER • C&V: ZTL • Max Over Threshold : 550 • Date: 2010-04-12 23:50:55

  16. Antenna Monitoring • Assertion The position error (RSS) for each WAAS reference station antenna is 10cm or less when measured relative to the ITRF datum for any given epoch. (Mexico City is allowed 25cm). The ITRF datum version (realization) is the one consistent with WGS-84 and also used for positions of the GPS Operational Control Segment monitoring stations.

  17. Purpose • Accurate antenna positions needed to support DGPS applications • Correct for Time Dependent Process • Tectonic Plate Movement • Subsidence • Correct for Shift Events • Seismic • Maintenance • WIPP Review for integrity issues • Greater than 10 cm WIPP should review • Greater than 25 cm WIPP must review • Special case for Mexico City (25 cm for review) • Project the need for a WAAS Antenna Coordinate Update

  18. Survey Details • Survey Date • 2010-05-03 (1582d1) • Cross Compared Against • CSRS-PPP • All Coordinates Projected to midpoint of WFO Release 2a and WFO Release 3 • 2011-04-01

  19. Results • Against CSRS-PPP • All sites less than 5 cm. except MMX • MMX ~10 cm Average Deltas

  20. Code Carrier Coherence • Assertion The a priori probability of a CCC failure is less than 1x10-4 per set of satellites in view per hour for GPS satellites and 1.14x10-4 for GEO satellites.

  21. Code Carrier Coherence Monitoring Approach • Monitor for all CCC Trips • All CCC Monitor Trips are investigated • For GEO Satellites • Plots of the CCC test statistic for GEO satellites are analyzed whenever a trip occurs to determine the source of the trip • Used the first 4 days of every week for the entire quarter

  22. Code Carrier Coherence Trips Date GEO C&V 2010-04-04 10:28:10 138 ZTL 2010-04-06 20:37:43 138 ZLA ZTL 2010-04-23 17:52:09 135 ZTL 2010-07-06 09:50:05 138 ZDC ZTL 2010-07-06 09:50:32 138 ZLA ZTL 2010-07-06 09:55:07 138 ZDC ZLA ZTL 2010-07-07 21:03:12 138 ZDC 2010-07-07 21:03:15 138 ZLA 2010-07-08 21:21:12 138 ZDC ZLA 2010-07-09 20:54:29 138 ZDC ZLA

  23. CCC diagnostic plot for 2010-04-06

  24. CCC UDREI Mean / Max for L1

  25. CCC UDREI Mean / Max for L2

  26. Signal Quality Monitor Assertion The a priori probability of a signal deformation (SD) failure is less than 2.4x10-5 per set of satellites in view per hour for GPS or GEO satellites. The worst-case range errors due to nominal signal deformations are more than 25cm on any satellite signal relative to the other satellites in view. Monitoring Approach All SQM Trips will be monitored for and investigated Max and Median data for each metric will be plotted by Requested UDRE Monitoring for discrepancies between satellite Plots are for the first 4 days of every week for the entire quarter Plots were made using the tools from HMI Build 299

  27. SQM Metric 1 Median / Max for Requested UDRE

  28. SQM Metric 2 Median / Max for Requested UDRE

  29. SQM Metric 3Median / Max for Requested UDRE

  30. SQM Metric 4 Median / Max for Requested UDRE

  31. GEO Signal Quality • Assertion The WAAS SIS satisfies the requirements for code-carrier coherence and fractional coherence stated in sections 3.1.4.2 and 3.1.4.3 of the [draft] system specification FAA-E-2892c • Monitoring Approach • Collect WAAS SIS data from each GEO using GUST receivers connected to dish antennas • Compute and plot the metrics outlined in sections 3.1.4.2 and 3.1.4.3 of FAA-E-2892c • Examine plots, tabulate max metric values and pass/fail states, analyze failures in further detail to identify possible causes

  32. Performance Summary 32

  33. PRN 135 Short-term CCC Note: missing values indicate days with switchovers or incomplete data 33

  34. PRN 135 Long-term CCC Note: missing values indicate days with switchovers or incomplete data 34

  35. PRN 135 Short-term CC Note: missing values indicate days with switchovers or incomplete data 35

  36. PRN 135 Long-term CC Note: missing values indicate days with switchovers or incomplete data 36

  37. PRN 138 Short-term CCC Note: missing values indicate days with switchovers or incomplete data 37

  38. PRN 138 Long-term CCC Note: missing values indicate days with switchovers or incomplete data 38

  39. PRN 138 Short-term CC Note: missing values indicate days with switchovers or incomplete data 39

  40. PRN 138 Long-term CC Note: missing values indicate days with switchovers or incomplete data 40

  41. Code Noise and Multipath (CNMP) Overbounding • Assertion • The Code Noise and Multipath (CNMP) error bound is sufficiently conservative such that the error in linear combinations of L1 and L2 measurements is overbounded by a Gaussian distribution with a sigma described by the Root Sum Square (RSS) of L1 and L2 CNMP error bounds except for biases, which are handled separately.3 • Monitoring Approach • Bounding for L1, IFPR, Delay • Aggregate and WRE Slices • All bounding failures analyzed in further detail

  42. Equations Used • Cumulative distribution function (CDF): • For examining the behavior at larger values of x: • Pass is Δx > 0 for all |x|>0.25

  43. Aggregate Plot of CNMP Delay

  44. Aggregate Plot of CNMP IFPR

  45. Aggregate Plot of CNMP RDL1

  46. CNMP Tabular Results from WRE Slices *These are the 5 sites with the highest |max| for L1

  47. Summary • Quarterly monitoring results continue to support specific assertions called for in the HMI document. • All antenna positions are within 5 cm, except MMX. • The CCC Test Statistic for the GEOs is near the trip threshold frequently.

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