FAA’s Plan for the Future Use of GPS Briefed By: Kanwaljit S. Sandhoo (MITRE/CAASD) 8th European CGSIC/IISC Meeting, Prague December 2-3, 1999

Overview lBackground lFAA Objectives lOperational Use of L5 lDual Frequency SBAS/GBAS lFAA’s Plan lSummary

Background lIn January 1999 the United States announced, that as a part of the GPS Modernization effort, two additional GPS signals will be made available for civil use —L2 at MHz will be available on GPS satellites to be launched beginning in 2003 for non-safety critical applications —L5 at MHz will be available on GPS/WAAS Satellites to be launched in 2005 for safety-of-life services like civil aviation l ARNS/RNSS allocation will ensure its protection for safety- of-life services lThe Interagency GPS Executive Board (IGEB) performed the analysis to support the selection of L5 and minimizing its impact on the existing system in the band

Background (Cont’d) RNSS (GLONASS) ARNS 1215 ARNS/RNSS (GLONASS) MHz +12 MHz MHz +12 MHz MHz +12 MHz (GPS) L5 L2 L1 GNSS Frequency Allocations Need RNSS Allocation for L5 to Support Civil Aviation Safety-of-Life Operations

FAA Objective lImprove the safety within NAS —Provide precision approach service at every qualified runway lImprove the safety throughout the World —Provide precision approach service throughout the World lIncrease the capacity of NAS —Direct & flexible routing not based on the location of ground-based navigation aids

Operational Use of L1 & L5 lCurrent SBAS/WAAS and GBAS/LAAS broadcast corrections on a single GPS frequency (L1) lIndependent Study by John Hopkins University Applied Physics Laboratory —Confirmed the technical feasibility of WAAS & LAAS —Recommended FAA make every effort to mitigate effects of intentional & unintentional interference lIn response to John Hopkins Study, the FAA is planning to use a more robust L5 signal as a Backup to L1 —L5 will have the same data as L1 —L5 will be a 20 MHz signal with 6dB more power than L1

Operational Use of L1 & L5 (Cont’d) lAvailability of L5 will facilitate the development and use of dual frequency avionics to eliminate ionospheric errors —Facilitates precision approach throughout the World at minimum or no cost to many countries

Dual Frequency SBAS/WAAS L MHz

Dual Frequency GBAS/LAAS L MHz L MHz

SBAS GEOs Coverage SGC=SBAS GEO CoverageSGC OIG =SGC Outside Ionospheric-Correction Grid SGC IIG =SGC Inside Ionospheric-Correction Grid SGC OIG SGC SGC OIG SGC IIG SGC OIG

SBAS Operations Inside Ionospheric-correction Grid lWAAS will broadcast ionospheric corrections and integrity data (satellite clock and ephemeris corrections) on both L1 and L5 lWhen Both L1 & L5 are available the users will use both the frequencies to provide the most accurate service possible —Onboard generated dual frequency corrections with integrity data from WAAS corrections broadcast at L1/L5 lIn the event of interference on any one of the frequencies (L1 or L5), the users will be able to use WAAS broadcast ionospheric corrections and integrity data

SBAS Coverage Outside Ionospheric-correction Grid lThe availability of L5 offers the potential of providing immediate access to the precision approach capability throughout the Footprint of SBAS GEO satellites at minimal or no cost to many nations lUsers will be able to use dual frequency avionics with integrity data from SBAS corrections broadcast at L1 or L5 lIn the event of Interference on L1 or L5 these regions can revert to non-precision approach —GPS with integrity data from SBAS correction broadcast at L1/L5 or use RAIM

Summary lFAA plans to use both L1 & L5 to achieve seamless global navigation lSafety-critical civil aviation and land-based application will benefit from the availability of L5 lL5 is being designed to be more robust and resistant to interference lL5 will be redundant to L1 lL5 will provide immediate access to precision approach capability throughout the World, within the footprint of SBAS GEO satellites at minimal or no cost to many nations