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Panel 1 NPECAB

Leadership Panel, Issue 1 Remove S/A Capability from System. BackgroundRemoval has been urged by independent Panels for over 10 years Capability is trivially defeated by GPS differential Systems (WAAS, NDGPS, etc.)It Flags the Military Control of GPS". The Good News: It was Officially remove

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Panel 1 NPECAB

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    1. Panel 1 NPECAB September 2007

    2. Leadership Panel, Issue 1 Remove S/A Capability from System Background Removal has been urged by independent Panels for over 10 years Capability is trivially defeated by GPS differential Systems (WAAS, NDGPS, etc.) It Flags the Military Control of GPS

    3. Seattle RAIM Availability Comparison

    4. Prioritizing the Big Five Goals for GPS Assured Availability of GPS signals-Including impaired situations (mountains, urban areas, foliage, etc.) (Signal has to be broadcast and in view) Resistance to Interference (RFI) (User must receive it) Accuracy (Ranging Error and Geometry must meet need) Bounded inaccuracy (Wild points limited by Good Geometry and bounds on ranging error) Integrity - eliminating HMI, meeting required time to alarm (Satellite runaway must be very improbable)

    5. THE Big Five Goals for GPS Assured Availability of GPS signals-Including impaired situations (mountains, urban areas, foliage, etc.) Number of GPS Satellites/Geometry Interoperability and Standardization with Galileo et al Resistance to Interference (RFI) Additional Satellite RF power and Frequency Diversity More jam resistant GPS receivers Accuracy Require Prediction Accuracy (Satellite Clocks and Age of Update) Good Satellite Geometry is essential Augmentations: WAAS, LAAS,EGNOS, MSAS, NDGPS, PLs Bounded inaccuracy to limit wild points Concerned with the 1% or less wild data points Good Satellite Geometry Coverage is Imperative Integrity - eliminating HMI, meeting required time to alarm RAIM WAAS Satellite Design Self Checking

    6. A Caution: The Under - emphasized Goal For many users, accuracy is of less concern than the bounds on inaccuracy. GPS errors do not follow a true Gaussian (called Normal) distribution, particularly regarding outliers Need more emphasis on this element of the big 5. We should insure that all improvements are backward compatible.

    7. More Observations Not practical for GPS to have service level based guarantees that are universally useful to all users Perhaps a new paradigm of service is needed Define component services (e.g. pseudorange accuracy) that will be exploited by all users to produce required service levels Provide performance guarantees on components such that end users can derive meaningful performance measures in the context of their application

    8. Panel 1: Meeting User Needs with Affordable Progress - Recommendations Place GPS III quickly under contract with early delivery Formally Commit to current Level of Service Insure Affordability enable service without brownouts Place GPS signal and availability under a true National Committee Tied to Approval Authority (strong participation by users as well as government agencies e.g. RTCA, NSTAC)

    9. The Brownout Danger Current GPS Average on-orbit life - 8.9 years First IIF currently launch ready ICA 50%: February 2009 First GPS III currently available for Launch - December 2013

    10. Overview from GPS III IRT(one element) A 30+X constellation is much more important & higher priority than Spot-Beams and Wide Band Crosslinks Blindly pursuing all the current Requirements would be expensive, risky & late Expensive, Complex Satellites will threaten schedule and, ultimately, the constellation size Block size should be 8 to attain 30+X constellation Requires Senior acceptance and direction

    11. Illustrating why current number of Satellites is Minimal (Courtesy GPS World and John Lavrakas) DOP is strongly driven by Masking Angle and number of satellites (the impaired users problem) Above 10o, less than 30 satellites destroys accuracy and availability

    12. A New Development: Aircraft Landing and Relative RAIM Provides the integrity to allow aircraft to Land at regional airports in bad weather Use lightly instrumented third-world landing fields with safety Without any Ground Augmentation Potentially helps the military Bounded Inaccuracy goal with a rigorous self check Requires at least 30 satellites for reliable operation

    17. Integrity for ATC and Aircraft Landing using Relative RAIM

    18. The Military Need for 30 + X Summary

    19. Background DSB Recommendations To support all DOD users, & provide adequate signal availability in urban canyons, mountainous terrain (typical masking angles of 15 to 20 degrees) the GPS constellation should be specified as 30 SVs plus adequate spares (30+X) To insure affordability, constrain GPS III satellite size to enable dual launch (insure 30 SVs are attainable) S/A capability-- no operational value: no further resources should be expended to place it on GPS III

    20. Reality Check Mask Angle Extend right arm directly forward with thumb up Close the hand and form a fist The angle as seen from the bottom to the top of the fist is very close to 10 degrees

    21. 14th AF assessment of GPS operations in IRAQ & Afghanistan -- Feb 2006 14th AF Recent on-site Observations Afghanistan Poor Availability--degraded due to mountains (high masking angles) Minimal RFI - terrain shielding Iraq Jamming/RFI ~85% known blue force interference 15% unknown Number of GPS receivers Military & Civilian unknown - significant number of both

    22. Why Affordability is so Critical

    23. Affordability Recommendation DOD should commit to providing a 30 Satellite constellation 98 % of the time and a 27 satellite constellation 100 % of the time To insure that commitment is met, steps should be taken to resist escalating costs: Specify Dual Launch Eliminate modules not essential to the primary mission Do not allow requirements creep to expand the IIIA design beyond the essential first step

    24. Panel 1 Summary: Meeting User Needs with Affordable Progress - Recommendations Place GPS III quickly under contract with early delivery Provides significant improvements over IIF Insurance against Brownouts (150 million users) Formally Commit to current Level of Service So Civil Users can take advantage of proven capabilities e.g. 30 + x Satellites Geometrically Optimized for Users Insure Military Availability in impaired regions Meet the Projected Capabilities of Compass and Galileo Support world-wide use to reduce Aircraft congestion (RRAIM) Insure Affordability enable service without brownouts Avoid non-GPS requirements (NDS et. al.) Dual Launch Fund a sensible fast-track development Place GPS signal and availability under a true National Committee Tied to Approval Authority (strong participation by users as well as government agencies e.g. RTCA, NSTAC) Assures signal is truly compatible and Maximizes Usefulness

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