GPS Modernization & WAAS for the 10th Korean GNSS Workshop Nov. 21 & 22, 2003 by Per Enge with thanks to the FAA & my colleagues at Stanford University copyright Per Enge, 2003

GPS Modernization New signals for frequency diversity Integrity machines (WAAS & LAAS) RFI hardening other radio measurements (Loran-C, television signals, basic backup network) receiver hardening (adaptive antennas, inertial measurements assisted GPS Ground control segment a few new stations a lot of new software copyright Per Enge, 2003

GPS Ranging copyright Per Enge, 2003

Scatter Plots (cartoons actually) for Stand Alone GPS & DGPS 1 m 1 m 5 m 5 m copyright Per Enge, 2003

Scatter Plots for DGPS at Long Range & Differential Carrier Phase 1 m 1 m 5 m 5 m copyright Per Enge, 2003

GPS Signals: Present and Future Today’s satellites New satellites launched beginning in 2004 New satellites launched near the end of the decade copyright Per Enge, 2003

GPS Signal Components: Navigation Data, PRN Code & RF Carrier 6000 km 300 m 19 cm copyright Per Enge, 2003

Auto-Correlation Properties Time shift between replica code and received code copyright Per Enge, 2003

Faster Codes Give Better Performance in Noise and Multipath Correlation peak for C/A code or RC code (1 Mcps) -300 m 300 m Correlation peak for L5 code (10 Mcps) -30 m 30 m copyright Per Enge, 2003

Longer Codes Reduce Auto- & Cross-Correlation “Sidelobes” 100% C/A code sidelobes: 6.4% of main peak RC & L5 code sidelobes: 2.1% of main peak copyright Per Enge, 2003

Ionospheric Measurement copyright Per Enge, 2003

Wide Area Augmentation System Operational on July 10, 2003! GPS constellation Geostationary broadcast of 1.) Continental corrections 2.) Data for error bounds 3.) Ranging signal Uplink station Central processor Reference receivers copyright Per Enge, 2003

Dual Frequency Ionospheric Estimation Vertical Iono Dual Frequency Ionospheric Estimation Vertical Iono. on a Nominal Day (Juan Blanch) copyright Per Enge, 2003

Dual Frequency Ionospheric Estimation Storm Day (July 16th 2000) (Juan Blanch) copyright Per Enge, 2003

L1-only Single-Frequency Avionics (Dr. Shau Shiun Jan) copyright Per Enge, 2003

L1-L5 Dual-frequency Avionics (Dr. Shau Shiun Jan) copyright Per Enge, 2003

Radio Frequency Interference (RFI) GPS constellation RFI is most worrisome & probably most likely during approach Airport Property copyright Per Enge, 2003

Nominal Ionospheric Bound Coasting on L5 if L1 is Lost to Interference (requires a new flag from the message) L5-only WAAS Coast to L5 With Nominal Ionospheric Bound <5 <10 <12 <15 <20 <30 <40 <50 >50 99.9% VPL (m) copyright Per Enge, 2003

Summary GPS modernization includes: new signals integrity machines RFI hardening new ground control capability All three pieces will work together to provide some truly amazing capabilities. Three frequencies together will enable centimeter accuracies. copyright Per Enge, 2003

Wide-Laning 300 m 19 cm 86 cm wavelength copyright Per Enge, 2003

Beat Frequencies copyright Per Enge, 2003