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Report on SBAS Ionospheric Working Group. Todd Walter Stanford University http:// waas.stanford.edu. SBAS Ionospheric Working Group. Chartered under the IWG to investigate ionospheric issues that jointly affect SBAS providers - PowerPoint PPT Presentation
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Report on SBAS Ionospheric Working Group
Todd WalterStanford University
http://waas.stanford.edu
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SBAS Ionospheric Working Group
Chartered under the IWG to investigate ionospheric issues that jointly affect SBAS providers
Led by Bertram Arbesser-Rastburg (ESA) and Patricia Doherty (Boston College)
First meeting in Canada in 1999 Attendees from Europe, U.S., and Canada Later meetings also included representatives from
Japan, India, and Brazil 19 meetings held to date (one to two a year) Most recent meeting – April 2012 at ITCP in Trieste in
conjunction with African Outreach Workshop Next meeting in two weeks in Bath, England
Ionospheric Working Group Major Activities
Facilitate interaction of ionospheric scientists supporting SBASExchange of data and ideasCoordinate research and data collectionHarmonize threats and threat models
Produced two major White Papers “Ionospheric Research Issues for SBAS”
Released Feb 2003 on ionospheric effects “Effect of Ionospheric Scintillation on GNSS”
Released Nov. 2010 on scintillation
Available at: http://waas.stanford.edu3
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Current Topics of Discussion Monitoring networks Identification of ionospheric events Effects of recent storms Ionosphere modeling Correlation of scintillation fading on L1, L2,
and L5 Proposed MOPS change for scintillation Progression of solar cycle 24
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Solar Cycle 24
Next Meeting Agenda (1 of 2)
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Friday, 2013-07-12 09:00 Opening, Welcome, Approval of Agenda SBAS Status Reports 09:05 WAAS Status (Todd Walter) 09:25 EGNOS status (Stefan Schlueter) 09:45 GAGAN Status (P.V. Rama Rao) Plans for new Augmentation systems 10:00 Activities with ASECNA in Africa (Stefan Schlueter) 10:15 GBAS possibilities for Brazil (Ivan Kantor) Operational experience 10:50 Scintillation on GPS L1, L2 & L5 signals (Charles Carrano) 11:10 Impact of Ionosphere on EGNOS (Angeline Billot) 11:30 Scintillation effects on WAAS at solar max (Eric Altshuler) 11:50 EGNOS open service iono model (Roberto Prieto Cerdeira) 12:10 Comparison of EGNOS, global maps & experimental data at position domain (Claudia
Paparini) 12:20 Ongoing SBAS / Ionospheric training at ICTP (Sandro Radicella) Scintillation Observations and Modeling 14:00 Scintillation results from MONITOR Project (Yannick Beniguel) 14:20 Latest developments in GISM Scintillation model (Yannick Beniguel) 14:40 Scintillation observations in India (P.V. Rama Rao) Reports on Experimental Campaigns 15:00 Ionospheric scintillation and TEC studies over Brazil using GNSS [Eurico de Paula) 15:20 ESA Ionospheric activities at low latitudes (Roberto Prieto Cerdeira)
Next Meeting Agenda (2 of 2) Saturday, 2013-07-13 Experiments Continued 09:00 LISN Status (Pat Doherty) 09:20 LISN Processing and prelim results (Eric Altshuler) 09:40 IGS MGEX campaign (Richard Langley) 10:00 Comparison of modern scint-mon receivers (Keith Groves) Ionospheric Storms 10:15 New indicator for definition of iono storm conditions (Jaume Sanz) 10:50 Discussion on way forward Next Meeting A.o.B. 12:00 Close of meeting
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Summary
SBAS Ionospheric Working group continues to meet once to twice a year
Current focus on: addressing recommendations of Scintillation
White Paper collecting (and making available) data sets
for sharing planning updates of white paper as results
provide new information Next meeting in 2 weeks:
University of Bath, after the Beacon Satellite Symposium
Recent Ionospheric Effects on WAAS
Todd WalterStanford University
http://waas.stanford.edu
Summary of EffectsSince January 2013 there has been
one minor ionospheric storm that impacted WAAS service over CONUSJune 1, 2013
A few minor storms have had some impact over Alaska and/or CanadaMarch 17 & 27, May 16, 19, 25, & 26, &
June 7, 2013
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Kp
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Coverage (Storms)
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Nominal Mar. 17
Mar. 27 June 1
Coverage
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Apr. 4 June 7
Loss due to PRN 18 being out of service, not to the ionosphere
Largest Kp day of the quarter (Kp = 7)
Presented to: DistributionBy: Bill WannerDate: June 3, 2013
Federal AviationAdministrationEffect on WAAS from
Iono Activity on June 1, 2013
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Kp Index Chart
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Coverage vs. Time Charts
• This event affected WAAS early in the day (GMT time) on June 1
• For a comparison of a ‘good’ day and the coverage on June 1 the following two slides shows CONUS and Alaska coverage for June 1 and June 2
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Coverage vs. Time Charts – CONUS – May 31 vs June 1
May 31, 2013 June 1, 2013
Iono activity from about 03:00 – 09:00 GMT
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Coverage vs. Time Charts – Alaska – May 31 vs June 1
May 31, 2013 June 1, 2013
Iono activity from about 03:00 – 09:00 GMT
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LPV-200 Coverage – June 1, 2013
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RNP 0.1 Coverage – June 1, 2013
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Accuracy – WAAS User• Accuracy was higher on June 1 than other days
– Both horizontal and vertical position errors were higher• Next two charts show the HPE and VPE, respectively, at the
Seattle WAAS reference station on June 1 and June 2– Seattle is used as an example
• The maximum HPE at Seattle is normally less than 1.5 meters– The maximum HPE was about 2.9 meters on June 1– HPL was 22.5 meters at the time of the maximum error
• HPE/HPL ratio = .13
• The maximum VPE at Seattle is normally less than 3 meters– The maximum VPE was about 6.8 meters on June 1– VPL was 25.3 meters at the time of the maximum error
• VPE/VPL ratio = .27, the highest of all WAAS sites on June 1 but VPE was still very well bounded by VPL
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Accuracy – GPS User• The following table shows a comparison of the calculated accuracy
for a single frequency L1 SPS user and a position solution using dual frequency (L1 and L2) for several sites:
Site Name
Dual Frequency Horizontal Position
Error (m)
Dual Frequency Vertical Position
Error (m)SPS Horizontal
Position Error (m)SPS Vertical
Position Error (m)
Cold Bay 3.239 3.991 6.857 9.308
San Jose del Cabo 3.035 3.974 5.576 15.317
Los Angeles 2.903 5.079 4.786 11.373
Oakland 3.069 6.473 5.961 10.235
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EGNOS Coverage
• Since EGNOS is publishing LPV procedures we took a look at the 24 hour coverage plot
• The plot is based on data collected from the Atlantic City and Bangor NSTB reference receivers– Data from ENGOS GEO PRN 120
• On the next slide the top plot is WAAS and EGNOS LPV coverage on June 1 and the bottom plot is June 2– Little impact to EGNOS LPV coverage due to the iono activity on June
1 when compared to June 2• MSAS is included in the plot but there is no LPV approved
procedures that use MSAS
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WAAS/EGNOS Coverage June 1-2
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Conclusion
• Iono activity on June 1 caused a loss of LP, LPV, and LPV-200 coverage in the WAAS service volume
• Accuracy for a WAAS and single frequency GPS user was increased on June 1 compared to June 2
• EGNOS coverage was minimally impacted due to this iono event