1 / 28

Surveillance and Broadcast Services GPS Constellations and Support for Separation Standards: National Space Based Posi

Agenda. ObjectiveGPS Constellation PerformanceCurrent Separation StandardsRequired Integrity to Support Separation StandardsCurrent Specified 24 Satellite ConstellationFuture 24 Satellite Constellation27/30 Satellite ConstellationsConclusionsNext Steps. Separation Standards Analysis Objectiv

rich
Download Presentation

Surveillance and Broadcast Services GPS Constellations and Support for Separation Standards: National Space Based Posi

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

    1. Surveillance and Broadcast Services GPS Constellations and Support for Separation Standards: National Space Based Positioning, Navigation and Timing (PNT) Advisory Board

    2. Agenda Objective GPS Constellation Performance Current Separation Standards Required Integrity to Support Separation Standards Current Specified 24 Satellite Constellation Future 24 Satellite Constellation 27/30 Satellite Constellations Conclusions Next Steps

    3. Separation Standards Analysis Objective Determine the GPS constellation configuration that support various separation standards for the En Route and Terminal domains

    4. GPS Constellation Performance The GPS Standard Positioning Service (SPS) Performance Standard defines the minimum requirements for GPS performance In support of the service availability standard, 24 operational satellites must be available on orbit with 0.95 probability (averaged over any day) At least 21 satellites in the 24 nominal plane/slot positions must be set healthy and transmitting a navigation signal with 0.98 probability (yearly averaged) Achieved 95% Global Accuracy of 13m with a worst case 95% Site Accuracy of 36m GPS performance has historically exceeded the minimum SPS requirement Current Constellation has 31 satellites that are operational (28 usable as of August 29, 2007) Achieved 95% Global Accuracy of 4m with a worst case 95% Site Accuracy of 6m

    5. GPS Constellation Performance Availability of a defined level of integrity is basis for detemining GPS Constellation ability to support separation standards Integrity in ADS-B is termed Navigational Integrity Category (NIC) GPS terminology refers to integrity Horizontal Protection Limit (HPL) Analysis for GPS support of providing a separation standard will be based on the availability of the minimum integrity value necessary for a separation minima Analysis conducted by MITRE

    6. Current Separation Standards Analyzed all Terminal separation cases 5nm En Route 3nm Terminal 2.5nm Terminal on approach 1.5nm Terminal on staggered dependent approaches 4,300 feet on independent parallel approaches

    7. Required Integrity to Support Separation Standards MITRE Close Approach Probability Model is basis of determining integrity values that support a defined separation standard Calculates probability of close approach (aircraft actually separated by 200ft or less) when aircraft are displayed with a defined separation Compares the relative performance, using CAP as a metric, of ADS-B with todays radar separation Determines the minimum Navigational Accuracy Category and NIC value required from ADS-B avionics to support a defined separation minima CAP risk is the risk that an aircraft with a displayed separation of 5NM, 3NM, or other separation minima, has a true separation of 200 feet or less.CAP risk is the risk that an aircraft with a displayed separation of 5NM, 3NM, or other separation minima, has a true separation of 200 feet or less.

    8. MITRE Model Terminal Results: Summary MSSR Radar Cross Range Error Compared to NIC/NAC and NUC values of ADS-B that provide equivalent Close Approach Probability (CAP) of 10-12 to that of radar 10-12 probability selection based on ICAO acceptance of this risk value for comparative assessment of extending Mode S radar range to 250NM

    9. MITRE CAP Model Analysis Results Future Parallel Approach separation of 2500 feet is a lesser separation than existing PRM that is limited to runway spacing of 3400 feet or greater.Future Parallel Approach separation of 2500 feet is a lesser separation than existing PRM that is limited to runway spacing of 3400 feet or greater.

    10. NIC Relationship to Containment Radius (Rc)

    11. Current Specified 24 Satellite Constellation Assumptions 24 GPS Martinez constellation Single-frequency receiver Average availability of n-satellite failure (n=0-3) Availability assessed over 24 hours with 5 minute intervals No failures on operating satellites GPS constellations considered parametrically (standard 24 SV and degraded: 23, 22, and 21 SV constellations) No Baro Aiding or Inertial coasting capability in avionics Mask Angle is the minimum angle above the horizon at which a GPS satellite would be used in the position calculation

    12. 24 Satellite Constellation CONUS

    13. 24 Satellite Constellation - CONUS

    14. 24 Satellite Constellation - Alaska

    16. Future 24 Satellite Constellation Assumptions 24 GPS Martinez constellation Dual frequency (L1, L5) constellation, dual frequency avionics Average availability of n-satellite failure (n=0-3) Availability assessed over 24 hours with 5 minute intervals No failures on operating satellites GPS constellations considered parametrically (24 SV and degraded: 23, 22, and 21 SV constellations) No Baro Aiding or Inertial coasting capability in avionics

    18. 27/30 Satellite Constellations Assumptions Future GPS constellations - 27 satellite and 30 satellite constellations Dual frequency (L1, L5) constellation, dual frequency avionics Two and five degree mask angles Average availability of n-satellite failures (n = 0, 1, 2) No failures on operating satellites Availability assessed over 24 hours with 5 minute intervals No Baro Aiding or Inertial coasting capability in avionics

    19. 27 Satellite Constellation

    20. 30 Satellite Constellation

    21. Summary GPS Constellations with greater numbers of satellites Increase the availability for applying separation minima Provide support for all current and potential future separation minima even with SV failures Future Satellite Constellations with dual frequencies provide increased availability of separation minima

    22. Backup

    23. Conclusions 24 Satellite Constellation with all satellites operational Provides availability of >0.999 for 5NM En Route as well as 3NM, 2.5 NM and 1.5NM on Parallel Dependent Approach Terminal separation standards in most of CONUS and Alaska Support for Independent parallel approach is unlikely with a 24 satellite constellation due to poor availability Some areas in US have low availability (<0.999) of both terminal and En Route Separation Standards with a Mask Angle of either 2 or 5 degrees Decreasing the Mask Angle accepted by the receiver increases availability but not sufficient to support separation standards in all of CONUS or Alaska Any satellite failure results in poor availability (<0.99) for applying terminal or en route separations

    24. Conclusions Future 24 Satellite Constellation Provides availability of >0.99999 for 5NM En Route as well as all current Terminal separation standards with all satellites operational and a 2 degree mask angle A single satellite failure results in maintaining an availability of 0.999 or greater in supporting all terminal and en route separtaion standards When 2 or more satellites are failed GPS provides poor availability (<0.99) of integrity for applying en route and terminal separations

    25. Conclusions 27 Satellite Constellation Provides availability of >0.99999 to support all current separation standards Provides availablity of a NIC that supports reduction of separation standards Single satellite failure reduces availability of applying all separation standards in small area of CONUS to <0.999 when using a 5? Mask Angle Availability of all separation standards remains >0.99999 for a 2? Mask Angle during a single satellite failure. Dual satellite failures degrades availability for applying todays separation standards to as low as 0.99

    26. Conclusions 30 Satellite Constellation Provides availability of >0.99999 to support all current separation standards Provides availablity of a NIC that supports reduction of separation standards Single satellite failure does not impact availability of applying all current separation standards Two satellite failures reduces availability of applying all separation standards Over much of CONUS to >0.9999 when using a 5? Mask Angle In only small area of CONUS when using a 2? Mask Angle during a single satellite failure.

    27. 24 Satellite Constellation w/ WAAS - CONUS

    28. 24 Satellite Constellation w/ WAAS - CONUS

    29. 27/30 Satellite Constellation w/ WAAS

More Related