T. Sakai, K. Matsunaga, K. Hoshinoo, ENRI T. Walter, Stanford University T. Sakai, K. Matsunaga, K. Hoshinoo, ENRI T. Walter, Stanford University Prototype

T. Sakai, K. Matsunaga, K. Hoshinoo, ENRIT. Walter, Stanford University

T. Sakai, K. Matsunaga, K. Hoshinoo, ENRIT. Walter, Stanford University

Prototype of SBAS andEvaluation of the Ionospheric

Correction Algorithms

Prototype of SBAS andEvaluation of the Ionospheric

Correction Algorithms

ION NTM 2006ION NTM 2006Monterey, CAMonterey, CA

Jan. 18-20, 2006Jan. 18-20, 2006

ION NTM 18-20 Jan. 2006 Sakai, ENRIION NTM 18-20 Jan. 2006 Sakai, ENRI

SSLIDELIDE 22

• Implementation of the prototype of SBAS:Implementation of the prototype of SBAS:

– A prototype of SBAS has been successfully implemented;A prototype of SBAS has been successfully implemented;

– Outputs the complete SBAS messages; tested with the Outputs the complete SBAS messages; tested with the

SBAS user receiver simulator;SBAS user receiver simulator;

– The overall performance is comparable with the MSAS.The overall performance is comparable with the MSAS.

• Evaluation of ionospheric correction algorithms:Evaluation of ionospheric correction algorithms:

– Using the above prototype as an evaluation tool;Using the above prototype as an evaluation tool;

– Evaluation of the current algorithm: ‘Planar Fit’; the storm Evaluation of the current algorithm: ‘Planar Fit’; the storm

detector trips a lot during storm ionospheric condition;detector trips a lot during storm ionospheric condition;

– Proposed algorithm with the zeroth order fit reduces the Proposed algorithm with the zeroth order fit reduces the

protection levels to the third part of the current algorithm.protection levels to the third part of the current algorithm.

IntroductionIntroduction


SSLIDELIDE 33

• MSAS is now under operational test procedures for IOC:MSAS is now under operational test procedures for IOC:

– Protection levels are hugely conservative with large margiProtection levels are hugely conservative with large margi

ns; not reflecting the actual performance;ns; not reflecting the actual performance;

– Needs reducing protection levels to improve availabilityNeeds reducing protection levels to improve availability;;

• However, MSAS has no ‘Testbed’:However, MSAS has no ‘Testbed’:

– There is only the operational system; cannot be used for tThere is only the operational system; cannot be used for t

esting new algorithms;esting new algorithms;

– The prototype of SBAS will be a powerful tool for evaluatiThe prototype of SBAS will be a powerful tool for evaluati

on of new algorithms for improvement of MSAS.on of new algorithms for improvement of MSAS.

• QZSS is being developed in Japan; also needs a testbed for iQZSS is being developed in Japan; also needs a testbed for i

nvestigation of wide-area augmentation technique.nvestigation of wide-area augmentation technique.

MotivationMotivation


SSLIDELIDE 44

• Actually computer software running on PC and UNIX:Actually computer software running on PC and UNIX:

– ‘‘RTWAD’ written in C language (not MATLAB, sorry);RTWAD’ written in C language (not MATLAB, sorry);

– Consists of the essential components and algorithms of Consists of the essential components and algorithms of

WADGPS;WADGPS;

– Developed for study purpose; does not meet the safety reDeveloped for study purpose; does not meet the safety re

quirements for civil aviation navigation facilities.quirements for civil aviation navigation facilities.

• Generates the complete SBAS messages:Generates the complete SBAS messages:

– Outputs one message per second;Outputs one message per second;

– 250-bit message without FEC encoding;250-bit message without FEC encoding;

– Optional output in NovAtel $FRMA format; works as direct Optional output in NovAtel $FRMA format; works as direct

input to SBAS user receiver simulator.input to SBAS user receiver simulator.

Implemented PrototypeImplemented Prototype


SSLIDELIDE 55

$FRMA,272,86403.130,138,80811EA4,250,53081FFDFFDFFDFFDFFDFFDFFDFFDFFDFFD$FRMA,272,86403.130,138,80811EA4,250,53081FFDFFDFFDFFDFFDFFDFFDFFDFFDFFDFFDFFDFFFBBBBBBBBBBBBAC1CD280*7CFFDFFDFFFBBBBBBBBBBBBAC1CD280*7C$FRMA,272,86404.130,138,80811EA4,250,9A0C1FFDFFDFFDFFDFFDFFDFFDFFDFFDFFD$FRMA,272,86404.130,138,80811EA4,250,9A0C1FFDFFDFFDFFDFFDFFDFFDFFDFFDFFDFFDFFDFFFBBBBBBBBBBBBB7E76F80*0FFFDFFDFFFBBBBBBBBBBBBB7E76F80*0F$FRMA,272,86405.130,138,80811EA4,250,C661FFDFFDFFDFFDFFDFFFBBBBB880000000$FRMA,272,86405.130,138,80811EA4,250,C661FFDFFDFFDFFDFFDFFFBBBBB8800000000000000000000000000036CD8A40*700000000000000000000036CD8A40*70$FRMA,272,86406.130,138,80811EA4,250,5306FFBFFFF8000000000000000000000000000$FRMA,272,86406.130,138,80811EA4,250,5306FFBFFFF8000000000000000000000000000000000000000000002B963FC0*0D000000000000000002B963FC0*0D$FRMA,272,86407.130,138,80811EA4,250,9A091FFDFFDFFDFFDFFDFFDFFDFFDFFDFFD$FRMA,272,86407.130,138,80811EA4,250,9A091FFDFFDFFDFFDFFDFFDFFDFFDFFDFFDFFDFFDFFFBBBBBBBBBBBB806D3340*77FFDFFDFFFBBBBBBBBBBBB806D3340*77$FRMA,272,86408.130,138,80811EA4,250,C60D1FFDFFDFFDFFDFFDFFDFFDFFDFFDFF$FRMA,272,86408.130,138,80811EA4,250,C60D1FFDFFDFFDFFDFFDFFDFFDFFDFFDFFDFFDFFDFFFBBBBBBBBBBBB924AAE40*08DFFDFFDFFFBBBBBBBBBBBB924AAE40*08$FRMA,272,86409.130,138,80811EA4,250,5361FFDFFDFFDFFDFFDFFFBBBBB890000000$FRMA,272,86409.130,138,80811EA4,250,5361FFDFFDFFDFFDFFDFFFBBBBB89000000000000000000000000000021FE640*7300000000000000000000021FE640*73$FRMA,272,86410.130,138,80811EA4,250,9A61FFDFFDFFDFFDFFDFFFBBBBB8A0000000$FRMA,272,86410.130,138,80811EA4,250,9A61FFDFFDFFDFFDFFDFFFBBBBB8A00000000000000000000000000039994D00*050000000000000000000039994D00*05$FRMA,272,86411.130,138,80811EA4,250,C60A1FFDFFDFFDFFDFFDFFDFFDFFDFFDFFD$FRMA,272,86411.130,138,80811EA4,250,C60A1FFDFFDFFDFFDFFDFFDFFDFFDFFDFFDFFDFFDFFFBBBBBBBBBBBBA6BE8CC0*03FFDFFDFFFBBBBBBBBBBBBA6BE8CC0*03$FRMA,272,86412.130,138,80811EA4,250,530E1FFDFFDFFDFFDFFDFFDFFDFFDFFDFFD$FRMA,272,86412.130,138,80811EA4,250,530E1FFDFFDFFDFFDFFDFFDFFDFFDFFDFFDFFDFFDFFFBBBBBBBBBBBBA99E5040*0AFFDFFDFFFBBBBBBBBBBBBA99E5040*0A

Message Type IDMessage Type ID(6 MSBs)(6 MSBs)

PreamblePreambleMessage Message LengthLength

SBAS Satellite PRNSBAS Satellite PRN

TimeTime

CRCCRC

Message SampleMessage Sample


SSLIDELIDE 66

• Currently running in offline mode:Currently running in offline mode:

– Used for various evaluation activities;Used for various evaluation activities;

– RINEX observation files are input as monitor station obseRINEX observation files are input as monitor station obse

rvations; provided from GEONET continuous observation rvations; provided from GEONET continuous observation

network operated by GSI, Japan;network operated by GSI, Japan;

– Thus the distribution of monitor stations is variable and thThus the distribution of monitor stations is variable and th

e historical ionospheric storm events can be tested.e historical ionospheric storm events can be tested.

• Utilizes only code phase pseudoranges on dual frequencies:Utilizes only code phase pseudoranges on dual frequencies:

– Needs no carrier measurements;Needs no carrier measurements;

– Outputs one message per second although RINEX is 30-Outputs one message per second although RINEX is 30-

second sampling.second sampling.

Implemented PrototypeImplemented Prototype


SSLIDELIDE 77User Receiver SimulatorUser Receiver Simulator

• SBAS user receiver simulator:SBAS user receiver simulator:

– Also software running on PC and UNIX;Also software running on PC and UNIX;

– Processes RINEX observation file with L1 pseudorange; cProcesses RINEX observation file with L1 pseudorange; c

arrier smoothing applied;arrier smoothing applied;

– Decodes SBAS message stream (in NovAtel $FRMA recoDecodes SBAS message stream (in NovAtel $FRMA reco

rds) and apply them to the observations;rds) and apply them to the observations;

– Tested with WAAS and MSAS messages.Tested with WAAS and MSAS messages.

• The implemented prototype was evaluated by this simulator:The implemented prototype was evaluated by this simulator:

– With GEONET observations at some locations;With GEONET observations at some locations;

– Output messages work functional;Output messages work functional;

– Evaluates position accuracies and protection levels.Evaluates position accuracies and protection levels.


SSLIDELIDE 88Monitor StationsMonitor Stations

• We used GEONET sites as We used GEONET sites as monitor stations.monitor stations.

• Dual frequency observation Dual frequency observation sampled every 30 seconds.sampled every 30 seconds.

• 6 monitor stations similar to 6 monitor stations similar to the MSAS.the MSAS.

• 5 user locations for evaluation.5 user locations for evaluation.

GEONET for Monitor StationsGEONET for Monitor Stations

GEONET for User StationsGEONET for User Stations

MSAS Service AreaMSAS Service Area


SSLIDELIDE 99Example of User Position ErrorExample of User Position Error

• Example of user positioning error Example of user positioning error at Site 940058 (Takayama; near at Site 940058 (Takayama; near center of monitor station networcenter of monitor station network).k).

• Period: 22-24 July 2004; active ioPeriod: 22-24 July 2004; active ionosphere condition.nosphere condition.

Standalone GPSStandalone GPSAugmented by the PrototypeAugmented by the Prototype

HorizontalHorizontalErrorError

VerticalVerticalErrorError

1.929 m1.929 m 3.305 m3.305 m

6.993 m6.993 m 14.48 m14.48 m

SystemSystem

StandaloneStandaloneGPSGPS

0.381 m0.381 m 0.531 m0.531 m

2.867 m2.867 m 5.451 m5.451 mPrototypePrototype

RMSRMS

MaxMax

RMSRMS

MaxMax


SSLIDELIDE 1010

2005/11/14-162005/11/14-16

HorHor VerVer

2004/7/22-242004/7/22-24

HorHor VerVer

2004/6/22-242004/6/22-24

HorHor VerVer

2005/11/14-162005/11/14-16MSASMSAS

HorHor VerVer

0.3540.3541.6951.695

0.4180.4182.5172.517

0.4320.4322.3182.318

0.5660.5664.4554.455

0.3970.3972.0472.047

0.6020.6024.7174.717

0.3810.3811.6591.659

0.6310.6312.4052.405

0.3040.3041.4871.487

0.4130.4132.1232.123

0.3810.3812.8672.867

0.5310.5315.4515.451

0.4250.4252.6342.634

0.6030.6033.4663.466

0.5020.5024.8734.873

0.7280.7283.7003.700

0.3530.3531.9021.902

0.5080.5084.4524.452

0.4030.4032.4682.468

0.5920.5924.2404.240

0.3850.3851.7571.757

0.6490.6493.7823.782

0.6370.6378.5178.517

0.8810.8819.3969.396

940030940030

940058940058

940083940083

0.4530.4533.3023.302

0.6470.6476.1586.158

0.5860.5862.1432.143

0.7640.7645.5095.509

0.4910.4912.4152.415

0.7760.7764.5744.574

0.6400.6403.0123.012

0.7300.7302.6802.680950491950491

1.1321.1326.2666.266

1.1021.1025.9585.958

080008004.4874.487

1.3171.3179.2259.225

0.7080.7084.5074.507

1.0881.0886.5956.595

0.9820.9826.2676.267

1.0141.0146.6146.6149200392003

RMSRMSMaxMax

RMSRMSMaxMax

RMSRMSMaxMax

RMSRMSMaxMax

RMSRMSMaxMax

SiteSite

NorthNorth

SouthSouth

Performance (Nominal)Performance (Nominal)

Unit: [m]Unit: [m]


SSLIDELIDE 1111Performance (Severe Storm)Performance (Severe Storm)

2004/11/8-102004/11/8-10

HorHor VerVer

2003/10/29-312003/10/29-31

HorHor VerVer

1.5461.5467.4797.479

1.9001.90011.4411.44

0.9820.9825.6455.645

1.0571.0576.5426.542

1.1571.1577.2217.221

1.5601.5609.2659.265

0.6590.6595.1945.194

0.8400.8406.6526.652

1.0571.0576.3756.375

1.5591.55912.8012.80

1.4071.40714.9014.90

1.8631.86312.3812.38

940030940030

940058940058

940083940083

1.6391.63921.9021.90

2.1952.19523.0923.09

2.1642.16429.4229.42

2.9012.90136.3136.31950491950491

3.3023.30226.8426.84

3.4273.42738.8638.86

3.1213.12115.9315.93

3.3563.35621.6721.679200392003

RMSRMSMaxMax

RMSRMSMaxMax

RMSRMSMaxMax

RMSRMSMaxMax

RMSRMSMaxMax

SiteSite

NorthNorth

SouthSouth

• Large errors due to Large errors due to ionosphere.ionosphere.

• Users still protected within Users still protected within protection levels.protection levels.

Unit: [m]Unit: [m]


SSLIDELIDE 1212Protection Levels (Quiet)Protection Levels (Quiet)

Protection levelProtection level

Protection level of MSASProtection level of MSAS

Actual errorActual error

• Protection levels during quiet Protection levels during quiet ionosphere at site 950491 ionosphere at site 950491 (second southern user).(second southern user).

• Protects users with large Protects users with large margins.margins.

• MSAS provided further MSAS provided further conservative protection levels.conservative protection levels.


SSLIDELIDE 1313Protection Levels (Storm)Protection Levels (Storm)



• Protection levels during storm Protection levels during storm ionosphere at site 950491 ionosphere at site 950491 (second southern user).(second southern user).

• Still protects users with large Still protects users with large margins.margins.

• However protection levels However protection levels grow large; this means low grow large; this means low system availability.system availability.


SSLIDELIDE 1414

2005/11/14-162005/11/14-16

HorHor VerVer

2004/7/22-242004/7/22-24

HorHor VerVer

2004/6/22-242004/6/22-24

HorHor VerVer

2005/11/14-162005/11/14-16MSASMSAS

HorHor VerVer

20.0220.02 32.1132.11 22.5622.56 33.6933.69 21.7321.73 34.3234.32 25.8225.82 40.4840.48

19.4119.41 32.1832.18 22.0822.08 32.5832.58 27.0027.00 37.6937.69 32.8332.83 46.2946.29

21.6221.62 35.4635.46 23.1323.13 36.9936.99 21.3921.39 37.8237.82 37.6737.67 50.0850.08

940030940030

940058940058

940083940083

28.3728.37 43.9743.97 26.5926.59 41.2441.24 23.1423.14 39.3639.36 44.3444.34 56.2456.24950491950491

55.3455.34 65.3865.38 35.5835.58 56.1156.11 31.3231.32 53.7753.77 85.7985.79 123.0123.09200392003

SiteSite

Nom

inal

Nom

inal

Iono

sphe

reIo

nosp

here

Protection Level StatisticsProtection Level Statistics

2004/11/8-102004/11/8-10

HorHor VerVer

2003/10/29-312003/10/29-31

HorHor VerVer

101.3101.3 152.7152.7 127.7127.7 181.6181.6

91.6191.61 146.0146.0 191.0191.0 231.3231.3

89.7689.76 154.0154.0 152.5152.5 249.5249.5

940030940030

940058940058

940083940083

100.6100.6 167.7167.7 144.0144.0 229.7229.7950491950491

109.5109.5 188.6188.6 129.4129.4 216.9216.99200392003

SiteSite• RMS of protection levels in RMS of protection levels in

meters.meters.

• Grows large for storm Grows large for storm ionospheric conditions.ionospheric conditions.S

ever

e S

torm

Sev

ere

Sto

rmIo

nosp

here

Iono

sphe

re


SSLIDELIDE 1515ProblemsProblems

• WADGPS Corrections work well:WADGPS Corrections work well:

– Positioning accuracy is 0.3-0.6m horizontal and 0.4-0.8m Positioning accuracy is 0.3-0.6m horizontal and 0.4-0.8m

vertical, respectively, over mainland of Japan;vertical, respectively, over mainland of Japan;

– The largest vertical error was less than 40 meters; could The largest vertical error was less than 40 meters; could

support APV-I operation (HAL=40m, VAL=50m).support APV-I operation (HAL=40m, VAL=50m).

• Protection levels are hugely conservative:Protection levels are hugely conservative:

– HPL and VPL completely protected users;HPL and VPL completely protected users;

– However, protection levels were not reflecting the actual However, protection levels were not reflecting the actual

performance regardless of ionospheric activities;performance regardless of ionospheric activities;

– Needs reducing protection levels to improve availability.Needs reducing protection levels to improve availability.

• Investigates this problem using the prototype system.Investigates this problem using the prototype system.


SSLIDELIDE 1616VPL during StormVPL during Storm

• Vertical protection levels Vertical protection levels during storm ionosphere at during storm ionosphere at site 950491 (second site 950491 (second southern user) with the southern user) with the baseline algorithm.baseline algorithm.

• Most of VPL came from Most of VPL came from ionospheric component.ionospheric component.

• To reduce protection levels, To reduce protection levels, the primary issue is the primary issue is ionosphere.ionosphere.


Ionospheric componentIonospheric component



SSLIDELIDE 1717UIVE and Actual ResidualUIVE and Actual Residual

• UIVE (user ionospheric UIVE (user ionospheric vertical error) is interpolated vertical error) is interpolated from GIVE (grid ionospheric from GIVE (grid ionospheric vertical error).vertical error).

• 5.33 UIVE works as 5.33 UIVE works as ionospheric component of ionospheric component of protection levels.protection levels.

• Large margin even during Large margin even during historical severe storm.historical severe storm.

5.33 UIVE5.33 UIVE

Actual ionosphericActual ionosphericresidualresidual


SSLIDELIDE 1818

• Without the storm detector Without the storm detector algorithm, UIVE was algorithm, UIVE was computed like this.computed like this.

• The large UIVE in daytime is The large UIVE in daytime is resulted in by trip of storm resulted in by trip of storm detector.detector.

• The actual ionospheric The actual ionospheric residual exceeded 5.33 residual exceeded 5.33 UIVE only once even without UIVE only once even without storm detector.storm detector.

5.33 UIVE5.33 UIVE


UIVE without Storm DetectorUIVE without Storm Detector


SSLIDELIDE 1919

• The ionospheric storm detector caused a lot of false alert The ionospheric storm detector caused a lot of false alert

conditions lowering system availability:conditions lowering system availability:

– When storm detector trips, the associate GIVE value is When storm detector trips, the associate GIVE value is

set to the maximum.set to the maximum.

• To avoid such a problem there are two possible ways:To avoid such a problem there are two possible ways:

– Develop an alternative safety mechanism instead of the Develop an alternative safety mechanism instead of the

storm detector;storm detector;

– Develop a method to compute GIVE values instead of Develop a method to compute GIVE values instead of

setting to the maximum when storm detector trips.setting to the maximum when storm detector trips.

• Here we introduce the latter algorithm.Here we introduce the latter algorithm.

Storm Detector ProblemStorm Detector Problem


SSLIDELIDE 2020

0-th order fit(1 parameter)

Ionosphericdelay

Rmax1-st order fit

(3 parameters)

Estimated delay at IGP

• We can reduce the order of fit when the storm detector We can reduce the order of fit when the storm detector

trips; the planar model cannot be applied.trips; the planar model cannot be applied.

• Only one parameter needs to be estimated; equivalent to Only one parameter needs to be estimated; equivalent to

the weighted average.the weighted average.

• Let us see UIVE and the actual residuals induced by the Let us see UIVE and the actual residuals induced by the

zeroth order fit.zeroth order fit.

Introducing Zeroth Order FitIntroducing Zeroth Order Fit


SSLIDELIDE 2121UIVE by Zeroth Order FitUIVE by Zeroth Order Fit

• UIVE computed with the UIVE computed with the zeroth order fit without the zeroth order fit without the storm detector algorithm.storm detector algorithm.

• UIVE is larger than planar fit.UIVE is larger than planar fit.

• The largest residual was The largest residual was within 5.33 UIVE even during within 5.33 UIVE even during the historical storm events; the historical storm events; the zeroth order fit does not the zeroth order fit does not need the storm detector.need the storm detector.

5.33 UIVE5.33 UIVE



SSLIDELIDE 2222

• The zeroth order fit works well and protects residuals within The zeroth order fit works well and protects residuals within

5.33 UIVE even during storm ionospheric conditions.5.33 UIVE even during storm ionospheric conditions.

• Thus the following adaptive algorithm can be employed:Thus the following adaptive algorithm can be employed:

– 1. Apply the standard planar fit with the storm detector;1. Apply the standard planar fit with the storm detector;

– 2. If storm detector does not trip, employ resulted correcti2. If storm detector does not trip, employ resulted correcti

on and GIVE;on and GIVE;

– 3. Otherwise, or the number of IPPs is insufficient for the 3. Otherwise, or the number of IPPs is insufficient for the

standard planar fit, perform the zeroth order fit.standard planar fit, perform the zeroth order fit.

• This algorithm will reduce the number of IGPs with the maximThis algorithm will reduce the number of IGPs with the maxim

um GIVE due to trip of storm detector.um GIVE due to trip of storm detector.

Adaptive AlgorithmAdaptive Algorithm


SSLIDELIDE 2323Protection Levels (Storm)Protection Levels (Storm)

• Reduced protection levels to the third part; improved availability.Reduced protection levels to the third part; improved availability.• Still protects users with large margins.Still protects users with large margins.

Baseline AlgorithmBaseline Algorithm Adaptive AlgorithmAdaptive Algorithm


SSLIDELIDE 2424GIVE StatisticsGIVE Statistics

Baseline algorithmBaseline algorithm

Adaptive algorithmAdaptive algorithm

• Current baseline algorithm pCurrent baseline algorithm produced the maximum GIVE roduced the maximum GIVE (GIVEI=14) for 50% of IGPs.(GIVEI=14) for 50% of IGPs.

• The adaptive algorithm reduThe adaptive algorithm reduced the maximum GIVE conced the maximum GIVE conditions and replaced to GIVEditions and replaced to GIVEI=13.I=13.

GIVEI = 15GIVEI = 15Not MonitoredNot Monitored

GIVEI = 14GIVEI = 14Maximum GIVEMaximum GIVE


SSLIDELIDE 2525

2004/11/8-102004/11/8-10

HorHor VerVer

2003/10/29-312003/10/29-31

HorHor VerVer

101.3101.327.3127.31

152.7152.741.8341.83

127.7127.732.7332.73

181.6181.648.8848.88

91.6191.6122.9322.93

146.0146.037.3637.36

191.0191.031.3231.32

231.3231.347.8747.87

89.7689.7624.6924.69

154.0154.041.0541.05

152.5152.540.1440.14

249.5249.561.9561.95

940030940030

940058940058

940083940083

100.6100.629.7329.73

167.7167.748.6548.65

144.0144.041.1341.13

229.7229.764.0164.01950491950491

109.5109.538.2638.26

188.6188.665.2165.21

129.4129.444.0144.01

216.9216.973.0073.009200392003

SiteSite

BaselineBaselineAdaptiveAdaptive





Reduction of Protection LevelsReduction of Protection Levels

• RMS protection levels RMS protection levels in meters during storm in meters during storm ionospheric conditions.ionospheric conditions.

• The adaptive algorithm The adaptive algorithm reduced protection reduced protection levels to the level of levels to the level of third part of the third part of the baseline algorithm.baseline algorithm.


SSLIDELIDE 2626

2004/11/8-102004/11/8-10 2003/10/29-312003/10/29-31

38.2 %38.2 %81.7 %81.7 %

29.2 %29.2 %62.8 %62.8 %

37.4 %37.4 %88.2 %88.2 %

26.1 %26.1 %65.9 %65.9 %

39.4 %39.4 %83.3 %83.3 %

15.8 %15.8 %36.8 %36.8 %

940030940030

940058940058

940083940083

38.6 %38.6 %69.6 %69.6 %

20.0 %20.0 %34.3 %34.3 %950491950491

26.3 %26.3 %34.6 %34.6 %

14.0 %14.0 %18.8 %18.8 %9200392003

SiteSite






LNAV/VNAV AvailabilityLNAV/VNAV Availability

2004/11/8-102004/11/8-10 2003/10/29-312003/10/29-31

37.1 %37.1 %77.6 %77.6 %

28.4 %28.4 %59.0 %59.0 %

36.9 %36.9 %86.8 %86.8 %

25.9 %25.9 %62.1 %62.1 %

39.1 %39.1 %81.6 %81.6 %

15.8 %15.8 %34.9 %34.9 %

38.3 %38.3 %68.7 %68.7 %

19.9 %19.9 %33.9 %33.9 %

25.7 %25.7 %33.8 %33.8 %

14.0 %14.0 %18.7 %18.7 %

APV-I (LPV) AvailabilityAPV-I (LPV) Availability

System AvailabilitySystem Availability


SSLIDELIDE 2727

• Realtime operation:Realtime operation:

– For implementation and tests integrity functions (TTA);For implementation and tests integrity functions (TTA);

– RTWAD runs with causality to input observations; little moRTWAD runs with causality to input observations; little mo

dification for realtime operation;dification for realtime operation;

– Signal biases will be computed day by day;Signal biases will be computed day by day;

– ENRI is installing realtime monitor stations; 6 stations up tENRI is installing realtime monitor stations; 6 stations up t

o now and one more shortly;o now and one more shortly;

• Evaluation activities in offline mode:Evaluation activities in offline mode:

– Effects of additional monitor stations (IGS stations);Effects of additional monitor stations (IGS stations);

– Testbed for dual frequency SBAS.Testbed for dual frequency SBAS.

Upcoming PlansUpcoming Plans


SSLIDELIDE 2828Realtime StationsRealtime Stations

• We have already installed 6 stWe have already installed 6 stations with realtime datalink to ations with realtime datalink to ENRI, Tokyo.ENRI, Tokyo.

• Additional station in Toyama is Additional station in Toyama is to be installed shortly.to be installed shortly.

MSAS StationsMSAS Stations

Realtime StatinsRealtime Statins

MSAS Service AreaMSAS Service Area


SSLIDELIDE 2929Experimental Equipment Experimental Equipment

Trimble 4000SSE in SapporoTrimble 4000SSE in Sapporo

NovAtel MiLLennium and IP convertersNovAtel MiLLennium and IP convertersat ENRI, Tokyoat ENRI, Tokyo


SSLIDELIDE 3030

• A prototype of SBAS has been successfully implemented:A prototype of SBAS has been successfully implemented:

– Overall accuracy: 0.3-0.6m horizontal and 0.4-0.8m vertical;Overall accuracy: 0.3-0.6m horizontal and 0.4-0.8m vertical;

– Protection levels completely protects users.Protection levels completely protects users.

• Evaluation of ionospheric correction algorithms using prototype:Evaluation of ionospheric correction algorithms using prototype:

– The current algorithm caused a lot of the maximum GIVE;The current algorithm caused a lot of the maximum GIVE;

– Adaptive algorithm will reduce the protection levels to the thirAdaptive algorithm will reduce the protection levels to the thir

d part of the current algorithm and improve availability.d part of the current algorithm and improve availability.• Future works will include:Future works will include:

– Realtime operation of prototype system;Realtime operation of prototype system;

– Simulation of dual frequency SBAS.Simulation of dual frequency SBAS.• Contact: [email protected]: [email protected]

ConclusionConclusion


SSLIDELIDE 3131Ionospheric Delay: QuietIonospheric Delay: Quiet


SSLIDELIDE 3232Ionospheric Delay: StormIonospheric Delay: Storm


SSLIDELIDE 3333

MCS Master Control StationMCS Master Control Station

MRSMRS

GMS Ground Monitor StationGMS Ground Monitor Station

Hitachiota MCSHitachiota MCS

Sapporo GMSSapporo GMS

Fukuoka GMSFukuoka GMS

Naha GMSNaha GMS

UserUser

Australia MRSAustralia MRS

Hawaii MRSHawaii MRS

Kobe MCSKobe MCS

Tokyo Tokyo GMSGMS

GPS ConstellationGPS ConstellationMTSATMTSAT

KDD 64KbpsKDD 64Kbps

NTT 64KbpsNTT 64Kbps

1Mbps1Mbps

Monitor and RangingMonitor and RangingStationStation

L-bandL-band

K-bandK-band

Ground LinkGround Link

• 2 GEO2 GEO• 2 MCS2 MCS• 2 MRS2 MRS• 4 GMS4 GMS

MSAS ArchitectureMSAS Architecture

Documents

T. Sakai, K. Matsunaga, K. Hoshinoo, ENRI T. Walter, Stanford University T. Sakai, K. Matsunaga, K. Hoshinoo, ENRI T. Walter, Stanford University Prototype