faa’s plan for the future use of gps briefed by: kanwaljit s. sandhoo (mitre/caasd) 8th european...
TRANSCRIPT
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
Background
FAA Objectives
Operational Use of L5
Dual Frequency SBAS/GBAS
FAA’s Plan
Summary
Background
In 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 1227.60 MHz will be available on GPS satellites to
be launched beginning in 2003 for non-safety critical applications
— L5 at 1176.45 MHz will be available on GPS/WAAS Satellites to be launched in 2005 for safety-of-life services like civil aviation ARNS/RNSS allocation will ensure its protection for safety-
of-life services The 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)
1176.45 MHz+12 MHz
1227.6 MHz+12 MHz
1575.42 MHz+12 MHz
15591260 1610960
(GPS)(GPS)
L5 L2 L1
GNSS Frequency Allocations
Need RNSS Allocation for L5 to Support Civil Aviation Safety-of-Life Operations
FAA Objective
Improve the safety within NAS— Provide precision approach service at every qualified
runway Improve the safety throughout the World
— Provide precision approach service throughout the World
Increase the capacity of NAS— Direct & flexible routing not based on the location of
ground-based navigation aids
Operational Use of L1 & L5
Current SBAS/WAAS and GBAS/LAAS broadcast corrections on a single GPS frequency (L1)
Independent 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 In 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)
Availability 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
L5 - 1176.45 MHz
L5 - 1176.45 MHz
L5 - 1176.45 MHz
Dual Frequency GBAS/LAAS
Pseudolite ReferenceAntennas
VHFTransmitter
Processing
Receiver
DataBroadcast
L1 - 1575.42 MHzL5 - 1176.45 MHz
SBAS GEOs Coverage
SGC=SBAS GEO Coverage SGCOIG=SGC Outside Ionospheric-Correction Grid
SGCIIG=SGC Inside Ionospheric-Correction Grid
SGCOIG
SGC
SGCOIG
SGCIIG
SGCOIG
SGCOIG
SGCOIG
SBAS Operations Inside Ionospheric-correction Grid
WAAS will broadcast ionospheric corrections and integrity data (satellite clock and ephemeris corrections) on both L1 and L5
When 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
In 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
The 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
Users will be able to use dual frequency avionics with integrity data from SBAS corrections broadcast at L1 or L5
In 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
FAA plans to use both L1 & L5 to achieve seamless global navigation
Safety-critical civil aviation and land-based application will benefit from the availability of L5
L5 is being designed to be more robust and resistant to interference
L5 will be redundant to L1 L5 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