Introductory Comments

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Introductory Comments
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Selected Background

• Constellation (Currently 29 on orbit)
• Average Age on orbit about 9 years
• IIF 1 not yet through Thermal Vac (Procuring 12)
• Remaining IIR and IIRMs are available
• DoD commitment is for 21 plus 3 orbiting spares
• Block IIIA (Launch 2013?)
• Now in System Design Review
• RFP not released Apparently held up in Pentagon
• DSB
• Recommended the constellation be fixed at 30
  plus spares

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Context GPS Big Five ObjectivesDeveloped by
the GPS IRT - generally accepted

1. Assured Availability of GPS
2. Resistance to Jamming and Interference
3. Accuracy (Usually the 50th percentile)
4. Bounded inaccuracy to limit wild points
   (Usually the 95th or 99th percentile)
5. Integrity - eliminating erroneous signals

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Attaining the GPS Big Five Objectives The
Main Drivers

• Assured Availability of GPS
• Constellation size and Reducing Outages
• Resistance to Jamming and Interference
• Multiple Signals, more EC Power, Improved UE
• Accuracy (Usually the 50th percentile)
• Constellation Size and Geometry
• More and improved Signals
• Improved Ranging Errors (satellite clocks)
• Bounded inaccuracy to limit wild points
  (Usually the 95th or 99th percentile)
• Same as Accuracy, but usually more stringent
• Integrity - eliminating erroneous signals
• Independent Cross checking (WAAS and EGNOS et.
  al.)
• Satellite Self Checking

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GPS Big Five ObjectivesWhat can we do to stay
world leaders?

• Assured Availability of GPS
• 30X significantly increases availability in
  impaired operations
• Moving ahead now on Block IIIA reduces risk of a
  significant gap
• Resistance to Jamming and interference
• More Earth Coverage signal power-
• Diversified all signal payload provides
  alternative, possibly un-jammed channels
• Adding the new Galileo/GPS signal L1C
• Augmenting GPS with dissimilar Positioning
  Capability
• Improved User Equipment for critical applications
  (e.g. beam steering antennas etc.)
• Accuracy
• 30x is a significant geometry improvement over
  nominal 24
• New Military and Civil signals
• more accurate ranging determination and
  resistance to multipath
• Better clocks enable more accurate signal in
  space
• Bounded inaccuracy to limit collateral damage and
  fratricide
• 30X provides redundant crosschecking by users
  (RAIM)
• Integrity - eliminating erroneous signals
• Satellite checking for runaway clocks and evil
  waveforms

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My three largest concerns

• Avoiding GPS Brownouts The need for
  proceeding immediately with IIIA
• Keeping IIIA simple and affordable Avoiding
  requirements creep developing on time and
  budget
• Avoiding/mitigating Interference (need for
  contingency augmentation - eLORAN)