Introductory Comments

1
Introductory Comments
2
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

3
Context GPS Big Five ObjectivesDeveloped by
the GPS IRT - generally accepted

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

4
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

5
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

6
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)