Impact of GPS Modernization

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Impact of GPS Modernization Galileo on Aviation
for the Lockheed Martin Advanced Technology
Center January 2007 by Per Enge
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The Global Positioning System
Space Segment
Spread Spectrum Ranging Signals Navigation Data
Clock Ephemeris
Control Segment
User Segment
Master Control Site
Five Monitor Stations Four Upload Stations
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Accuracy Stand Alone GPS Differential GPS
(from the Danish GPS Center)
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Professional Uses of GPS

• Land Information
• Survey stakeout
• Geodesy
• Seismic survey
• Earthquake Monitoring
• Volcano Monitoring
• Asset Mapping

• Attitude Heading
• Small Aircraft
• Satellites (GlobalStar)
• Ships

• Timing
• Communications
• Scientific
• Only requires 1 sv

• Navigation
• Ships (prevent Exxon Valdez)
• Airplanes
• Space (space station, satellites)

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Consumer Uses of GPS
(from Kanwar Chadha)
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Three Hard Problems

• Automatic landings of aircraft
• Extend coverage indoors downtown
• Discourage terrorists hackers

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Aerospace Safety Fault Detection

• Known signal features
• Known vehicle dynamics
• Satellite to satellite
• over-specified solution enables residuals test
• needs lots of satellites
• Known location on ground
• airport reference (LAAS)
• continental reference network (WAAS)
• these are expensive

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GPS Augmentation for SafetyLocal Area
Augmentation System (LAAS)
GNSS

• VHF data broadcast of
• airport corrections
• data for error bounding

Three or four GPS receivers
Central processor
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Aircraft Landing System Design is Dominated by
Fault Analysis
Northern Ohio Nov. 20, 2003 (from Seebany
Datta-Barua)
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Slant Delay Traces from 4 Northern Ohio Stations
(11/20/03)
(PRN 8)
Slope 300 to 400 mm/km Width 50 km Speed
250 m/s
2115
2040
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LAAS Error Bounds (from Jiyun Lee)
Error bound that can be protected with a
time-invariant algorithm.
Error bound that can be protected with a real
time algorithm
Error bound for all other error sources
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New GPS Signals Will Help
U.S. FAA launched first L5 signals in Fall of
2005
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GPS II-RM Signals
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New L5 Signals Launched for the FAA
PanAmSat Launched Oct 13, 2005 TeleSat
Launched Sept 8, 2005
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New Constellations Will Help
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Galileo Prototype Launched on Dec. 28, 2005
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New Monitor Dish
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Data Collection Block Diagram
Dish Antenna
L-band Feed
Antenna Front End
A/D
Software Receiver
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24 GPS Satellites
Ground monitors
Residuals test
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GPS Galileo
Ground monitors
Residuals test
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Future Autoland Based on GPS Inertial
Navigation
RFI
Final Approach Fix
Ground Facility with VHF Data Broadcast
Intermediate Approach Segment Inertial
Calibration with CDGPS CRPAs
Final Approach Segment 9 km INS navigation with
or without GPS
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Summary

• New satellite signals will help all three
  challenges, but
• Integrity continuity for auto-landing of
  piloted un-piloted aircraft
• fault modes are tough to anticipate in complex
  systems
• inertial navigation will play a strong role
• Downtown indoors
• WiFi WiMax (plus GNSS) will be the real
  enablers
• Discourage terrorists hackers
• harden the GNSS receivers (inertial aiding
  CRPAs)
• retain local (or regional) radio backups (like
  Loran)