t. sakai, t. yoshihara, s. fukushima, and k. ito electronic navigation research institute, japan

T. Sakai, T. Yoshihara, S. Fukushima, and K. ItoElectronic Navigation Research Institute, Japan

T. Sakai, T. Yoshihara, S. Fukushima, and K. ItoElectronic Navigation Research Institute, Japan

The Ionospheric Correction Processorfor SBAS and QZSS L1-SAIF

The Ionospheric Correction Processorfor SBAS and QZSS L1-SAIF

ION ITM 2009ION ITM 2009Anaheim, CAAnaheim, CA

Jan. 26-28, 2009Jan. 26-28, 2009

ION ITM 26-28 Jan. 2009 - ENRIION ITM 26-28 Jan. 2009 - ENRI

SSLIDELIDE 22

• MSAS has been operational since 2007:MSAS has been operational since 2007:– SBAS augmentation signal offers: wide-area differential correction, inteSBAS augmentation signal offers: wide-area differential correction, inte

grity function, and ranging function.grity function, and ranging function.

• QZSS will broadcast another augmentation signal in 2010:QZSS will broadcast another augmentation signal in 2010:– ENRI is developing L1-SAIF (Submeter-class Augmentation with IntegrENRI is developing L1-SAIF (Submeter-class Augmentation with Integr

ity Function) on GPS/SBAS L1 frequency;ity Function) on GPS/SBAS L1 frequency;

– Upper compatible with SBAS signal; Also offers WADGPS, integrity, anUpper compatible with SBAS signal; Also offers WADGPS, integrity, and ranging.d ranging.

• Ionosphere is a major problem for both systems:Ionosphere is a major problem for both systems:– Developed the Ionospheric Correction Processor (ICP) independent froDeveloped the Ionospheric Correction Processor (ICP) independent fro

m WADGPS correction processor;m WADGPS correction processor;

– Implemented and integrated with QZSS L1-SAIF Message Generator Implemented and integrated with QZSS L1-SAIF Message Generator (L1SMG); Tested successfully.(L1SMG); Tested successfully.

IntroductionIntroduction


SSLIDELIDE 33

Part 1Part 1

Overview of MSASOverview of MSASandand

QZSS L1-SAIF ProgramsQZSS L1-SAIF Programs


SSLIDELIDE 44WADGPS ConceptWADGPS Concept

Orbit CorrectionOrbit Correction

TroposphereTroposphere

IonosphereIonosphere

Ionospheric CorrectionIonospheric Correction

Tropospheric CorrectionTropospheric Correction

Clock CorrectionClock Correction• Same contribution to any user Same contribution to any user

location;location;• Not a function of location;Not a function of location;• Needs fast correction. Needs fast correction.

• Different contribution to different Different contribution to different user location;user location;

• Not a function of user location; but Not a function of user location; but a function of line-of-sight direction;a function of line-of-sight direction;

• Long-term correction.Long-term correction.

• Function of user location;Function of user location;• Up to 100 meters;Up to 100 meters;• Vertical structure may be Vertical structure may be

described as a thin shell.described as a thin shell.

• Function of user location, especially height of user;Function of user location, especially height of user;• Up to 20 meters;Up to 20 meters;• Can be corrected enough by a fixed model.Can be corrected enough by a fixed model.


SSLIDELIDE 55MSAS StatusMSAS Status

• Satellite navigation for civil aviation use:Satellite navigation for civil aviation use:– SBAS international standard;SBAS international standard;– Compatible with US WAAS and EuropCompatible with US WAAS and Europ

ean EGNOS.ean EGNOS.• MSAS facilities:MSAS facilities:

– 2 GEOs: MTSAT-1R (PRN 129) and 2 GEOs: MTSAT-1R (PRN 129) and MTSAT-2 (PRN 137) on orbit;MTSAT-2 (PRN 137) on orbit;

– 6 domestic GMSs and 2 RMSs (Hawa6 domestic GMSs and 2 RMSs (Hawaii and Australia) connected with 2 MCii and Australia) connected with 2 MCSs;Ss;

– IOC WAAS software with localization.IOC WAAS software with localization.• IOC service since Sept. 27, 2007:IOC service since Sept. 27, 2007:

– Certified for Enroute to NPA operationCertified for Enroute to NPA operations as a sole mean navigation;s as a sole mean navigation;

– Stable operation.Stable operation.

MTSAT-1RMTSAT-1R

MTSAT-2MTSAT-2


SSLIDELIDE 66MSAS PerformanceMSAS Performance

Horizontal Position AccuracyHorizontal Position AccuracyRMS 0.42m MAX 1.64mRMS 0.42m MAX 1.64m

GPSGPS

MSASMSAS@Kawagoe (93011)08/1/17-19 PRN129

Vertical Position AccuracyVertical Position AccuracyRMS 0.57m MAX 2.34mRMS 0.57m MAX 2.34m

GPSGPS

MSASMSAS

@Kawagoe (93011)08/1/17-19 PRN129


SSLIDELIDE 77Concerns for MSASConcerns for MSAS

• The current MSAS is built on the IOC WAASThe current MSAS is built on the IOC WAAS::– As the first satellite navigation system developed by Japan, the design teAs the first satellite navigation system developed by Japan, the design te

nds to be conservative;nds to be conservative;

– The primary purpose is providing horizontal navigation means to aviation The primary purpose is providing horizontal navigation means to aviation

users; Ionopsheric corrections may not be used;users; Ionopsheric corrections may not be used;

– Achieves 100% availability of Enroute to NPA flight modes.Achieves 100% availability of Enroute to NPA flight modes.

• The major concern for vertical guidanThe major concern for vertical guidan

ce is ionospherece is ionosphere::– The ionospheric term is dominant factor The ionospheric term is dominant factor

of position solution uncertainty;of position solution uncertainty;

– Necessary to reduce ionospheric uncertNecessary to reduce ionospheric uncert

ainty to provide vertical guidance with reainty to provide vertical guidance with re

asonable availability.asonable availability.


SSLIDELIDE 88

QZSQZSGPS/GEOGPS/GEO

• Signal from high elevation angleSignal from high elevation angle

• Applicable to navigation services for Applicable to navigation services for mountain area and urban canyonmountain area and urban canyon

QZSS ConceptQZSS Concept

• Footprint of QZS orbitFootprint of QZS orbit• Centered 137ECentered 137E• Eccentricity 0.1, Inclination 45degEccentricity 0.1, Inclination 45deg


SSLIDELIDE 99

• Supplement signals:Supplement signals:– GPS-compatible L1C/A, L2C, L5, and L1C signals working with GPS; GPS-compatible L1C/A, L2C, L5, and L1C signals working with GPS;

For improving availability of navigation;For improving availability of navigation;

– With minimum modifications from GPS signal specifications;With minimum modifications from GPS signal specifications;

– Coordination with GPS Wing on broadcasting L1C signal;Coordination with GPS Wing on broadcasting L1C signal;

– JAXA is responsible for all supplement signals.JAXA is responsible for all supplement signals.

• Augmentation signals:Augmentation signals:– Augmentation to GPS; Possibly plus Galileo;Augmentation to GPS; Possibly plus Galileo;

– L1-SAIF (Submeter-class Augmentation with Integrity Function): comL1-SAIF (Submeter-class Augmentation with Integrity Function): compatible with SBAS; reasonable performance for mobile users;patible with SBAS; reasonable performance for mobile users;

– LEX: for experimental purposes; member organizations may use as 2LEX: for experimental purposes; member organizations may use as 2kbps experimental data channel;kbps experimental data channel;

– ENRI is working for L1-SAIF and JAXA is developing LEX.ENRI is working for L1-SAIF and JAXA is developing LEX.

QZSS SignalsQZSS Signals


SSLIDELIDE 1010QZSS Frequency PlanQZSS Frequency Plan

SignalSignal ChannelChannel FrequencyFrequency BandwidthBandwidth Min. Rx PowerMin. Rx Power

QZS-L1CQZS-L1CL1CDL1CD

1575.42 MHz1575.42 MHz

24 MHz24 MHz ––163.0 dBW163.0 dBW

L1CPL1CP 24 MHz24 MHz – – 158.25 dBW158.25 dBW

QZS-L1-C/AQZS-L1-C/A 24 MHz24 MHz – – 158.5 dBW158.5 dBW

QZS-L1-SAIFQZS-L1-SAIF 24 MHz24 MHz – – 161.0 dBW161.0 dBW

QZS-L2CQZS-L2C 1227.6 MHz1227.6 MHz 24 MHz24 MHz – – 160.0 dBW160.0 dBW

QZS-L5QZS-L5L5IL5I

1176.45 MHz1176.45 MHz25 MHz25 MHz – – 157.9 dBW157.9 dBW

L5QL5Q 25 MHz25 MHz – – 157.9 dBW157.9 dBW

QZS-LEXQZS-LEX 1278.75 MHz1278.75 MHz 42 MHz42 MHz – – 155.7 dBW155.7 dBW

Find detail in IS-QZSS document.Find detail in IS-QZSS document.


SSLIDELIDE 1111

• QZSS will broadcast wide-area augmentation signal:QZSS will broadcast wide-area augmentation signal:– Called L1-SAIF (Submeter-class Augmentation with Integrity Function);Called L1-SAIF (Submeter-class Augmentation with Integrity Function);

– Developed by ENRI.Developed by ENRI.

• L1-SAIF signal offers:L1-SAIF signal offers:– Wide-area differential corrections for improving position accuracy; TargWide-area differential corrections for improving position accuracy; Targ

et accuracy: 1 meter for horizontal;et accuracy: 1 meter for horizontal;

– Integrity function for safety of mobile users; andIntegrity function for safety of mobile users; and

– Ranging function to improve signal availability.Ranging function to improve signal availability.

• Interoperable with GPS L1C/A and fully compatible with SBAS:Interoperable with GPS L1C/A and fully compatible with SBAS:– Broadcast on L1 freq. with RHCP; Common antenna and RF front-end;Broadcast on L1 freq. with RHCP; Common antenna and RF front-end;

– Modulated by BPSK with C/A code;Modulated by BPSK with C/A code;

– 250 bps data rate with 1/2 FEC; message structure is same as SBAS.250 bps data rate with 1/2 FEC; message structure is same as SBAS.

QZSS L1-SAIF SignalQZSS L1-SAIF Signal


SSLIDELIDE 1212SBAS/L1-SAIF Message StructureSBAS/L1-SAIF Message Structure

PreamblePreamble8 bits8 bits

Message TypeMessage Type6 bits6 bits

Data FieldData Field212 bits212 bits

CRC parityCRC parity24 bits24 bits

250 bits per second

MTMT

00

11

22～～ 55

66

77

99

1010

1212

1717

1818

ContentsContents

Test modeTest mode

PRN maskPRN mask

Fast correction & UDREFast correction & UDRE

UDREUDRE

Degradation factor for FCDegradation factor for FC

GEO ephemerisGEO ephemeris

Degradation parameterDegradation parameter

SBAS time informationSBAS time information

GEO almanacGEO almanac

IGP maskIGP mask

IntervalInterval[s][s]

66

120120

6060

66

120120

120120

120120

300300

300300

300300

2424

2525

2626

2727

2828

6363

FC & LTCFC & LTC

Long-term correctionLong-term correction

Ionospheric delay & GIVEIonospheric delay & GIVE

SBAS service messageSBAS service message

Clock-ephemeris covarianceClock-ephemeris covariance

Null messageNull message

66

120120

300300

300300

120120

——

MTMT ContentsContents IntervalInterval[s][s]

Transmitted FirstTransmitted First


SSLIDELIDE 1313SBAS/L1-SAIF Message (1)SBAS/L1-SAIF Message (1)

Message TypeMessage Type ContentsContents CompatibilityCompatibility StatusStatus

00 Test modeTest mode BothBoth FixedFixed

11 PRN maskPRN mask BothBoth FixedFixed

2 to 52 to 5 Fast correction & UDREFast correction & UDRE BothBoth FixedFixed

66 UDREUDRE BothBoth FixedFixed

77 Degradation factor for FCDegradation factor for FC BothBoth FixedFixed

1010 Degradation parameterDegradation parameter BothBoth FixedFixed

1818 IGP maskIGP mask BothBoth FixedFixed

2424 Mixed fast/long-term correctionMixed fast/long-term correction BothBoth FixedFixed

2525 Long-term correctionLong-term correction BothBoth FixedFixed

2626 Ionospheric delay & GIVEIonospheric delay & GIVE BothBoth FixedFixed

99 GEO ephemerisGEO ephemeris SBASSBAS FixedFixed

1717 GEO almanacGEO almanac SBASSBAS FixedFixed

1212 SBAS network timeSBAS network time SBASSBAS FixedFixed

88 ReservedReserved SBASSBAS FixedFixed


SSLIDELIDE 1414SBAS/L1-SAIF Message (2)SBAS/L1-SAIF Message (2)

Message TypeMessage Type ContentsContents CompatibilityCompatibility StatusStatus

2727 SBAS service messageSBAS service message SBASSBAS FixedFixed

29 to 5129 to 51 (Undefined)(Undefined) —— ——

2828 Clock-ephemeris covarianceClock-ephemeris covariance BothBoth FixedFixed

6262 ReservedReserved BothBoth FixedFixed

6363 Null messageNull message BothBoth FixedFixed

5252 TGP maskTGP mask L1-SAIFL1-SAIF TentativeTentative

5656 Intersignal biasesIntersignal biases L1-SAIFL1-SAIF TentativeTentative

5757 (Ephemeris-related parameter)(Ephemeris-related parameter) L1-SAIFL1-SAIF TBDTBD

5858 QZS ephemerisQZS ephemeris L1-SAIFL1-SAIF TentativeTentative

5959 (QZS almanac)(QZS almanac) L1-SAIFL1-SAIF TBDTBD

6060 (Regional information)(Regional information) L1-SAIFL1-SAIF TBDTBD

6161 ReservedReserved L1-SAIFL1-SAIF TentativeTentative

55３３ Tropospheric delayTropospheric delay L1-SAIFL1-SAIF TentativeTentative

54 to 5554 to 55 (Advanced Ionospheric delay)(Advanced Ionospheric delay) L1-SAIFL1-SAIF TBDTBD


SSLIDELIDE 1515

Part 2Part 2

Ionospheric Correction Processor (ICP)Ionospheric Correction Processor (ICP)and L1-SAIF Message Generatorand L1-SAIF Message Generator


SSLIDELIDE 1616

• L1-SAIF Master Station (L1SMS):L1-SAIF Master Station (L1SMS):– Generates L1-SAIF message stream in realtime and transmits them to QZGenerates L1-SAIF message stream in realtime and transmits them to QZ

SS MCS developed by JAXA;SS MCS developed by JAXA;– Installed at ENRI, Tokyo;Installed at ENRI, Tokyo;– Subsystems: GEONET Server, Primary Receiver, Interface Processor, MSubsystems: GEONET Server, Primary Receiver, Interface Processor, M

essage Generator, Ionosphere Processor, Troposphere Processor, and Bessage Generator, Ionosphere Processor, Troposphere Processor, and Batch Processor.atch Processor.

ENRI L1SMSENRI L1SMS

L1SMSL1SMSGEONETGEONET

QZSQZS

QZSS MCSQZSS MCS

GPSGPS

MeasuredMeasuredDataData

L1-SAIFL1-SAIFMessageMessage

GSIGSI ENRIENRI JAXAJAXA

L1-S

AIF S

ignal

L1-S

AIF S

ignalL1C/A, L2P

L1C/A, L2PL1

C/A, L

2P

L1C/A

, L2P K-band

K-bandClosedClosedLoopLoop


SSLIDELIDE 1717

• GEONET Server:GEONET Server:– Receives dual frequency measurement from GEONET operated by GReceives dual frequency measurement from GEONET operated by G

eographical Survey Institute (GSI), Japan;eographical Survey Institute (GSI), Japan;

– Output rate: 1 sample per second (1 Hz); In native binary format of recOutput rate: 1 sample per second (1 Hz); In native binary format of receivers; Latency is less than 2 seconds;eivers; Latency is less than 2 seconds;

– 5 servers for 1,000 GEONET stations distributed all over Japan.5 servers for 1,000 GEONET stations distributed all over Japan.

• Primary Receiver:Primary Receiver:– Installed inside L1SMS with connection via Ethernet LAN;Installed inside L1SMS with connection via Ethernet LAN;

– Provides measurements for immediate response to satellite failure to Provides measurements for immediate response to satellite failure to ensure integrity function;ensure integrity function;

– Collects navigation message every subframe;Collects navigation message every subframe;

– Provides the actual time to the message generator;Provides the actual time to the message generator;

– Currently NovAtel OEM-3 MiLLennium-STD.Currently NovAtel OEM-3 MiLLennium-STD.

L1SMS Subsystems (1)L1SMS Subsystems (1)


SSLIDELIDE 1818L1SMS Subsystems (2)L1SMS Subsystems (2)

• Interface Processor:Interface Processor:– Distributes GPS measurement data stream to other processors;Distributes GPS measurement data stream to other processors;

– Other subsystem processors access to this processor for measurements Other subsystem processors access to this processor for measurements to avoid generating lots of direct connections to GEONET Server and Prito avoid generating lots of direct connections to GEONET Server and Primary Receiver;mary Receiver;

– Also relays L1-SAIF message packets from Message Generator to QZSAlso relays L1-SAIF message packets from Message Generator to QZSS MCS at JAXA.S MCS at JAXA.

• Message Generator (L1SMG):Message Generator (L1SMG):– Generates L1-SAIF message with clock and orbit corrections;Generates L1-SAIF message with clock and orbit corrections;

– Variable configuration of monitor stations;Variable configuration of monitor stations;

– Accepts several types of receiver: RINEX, NovAtel, Trimble, JAVAD;Accepts several types of receiver: RINEX, NovAtel, Trimble, JAVAD;

– Standard planar fit algorithm for ionospheric correction; Identical with WAStandard planar fit algorithm for ionospheric correction; Identical with WAAS/MSAS ionospheric corrections;AS/MSAS ionospheric corrections;

– Standard correction model for troposphere.Standard correction model for troposphere.



• Ionospheric Correction Processor (ICP):Ionospheric Correction Processor (ICP):– Generates ionospheric correction and integrity information based on vast Generates ionospheric correction and integrity information based on vast

number of monitor stations;number of monitor stations;

– Tested with realtime measurements from up to 200 monitor stations;Tested with realtime measurements from up to 200 monitor stations;

– IGP location is not fixed and identified by QUERY command;IGP location is not fixed and identified by QUERY command;

– This processor is optional; If not exist, L1SMG employs its own standard This processor is optional; If not exist, L1SMG employs its own standard algorithm.algorithm.

• Tropospheric Correction Processor (under development):Tropospheric Correction Processor (under development):– Estimates atmospheric condition and generates tropospheric delay;Estimates atmospheric condition and generates tropospheric delay;

– Semi-realtime estimation: latency is less than 5 min;Semi-realtime estimation: latency is less than 5 min;

– Formats delay information into vertical delay at TGP (tropospheric grid pFormats delay information into vertical delay at TGP (tropospheric grid point) like IGP for ionosphere;oint) like IGP for ionosphere;

– Also optional; If not exist, standard troposphere model is used.Also optional; If not exist, standard troposphere model is used.



• Batch Processor:Batch Processor:– Estimates satellite and receiver hardware biases so-called Inter-frequeEstimates satellite and receiver hardware biases so-called Inter-freque

ncy bias or L1/L2 bias;ncy bias or L1/L2 bias;

– Runs on daily basis; Constructs model of ionosphere based on measurRuns on daily basis; Constructs model of ionosphere based on measurements for at least two days and performs estimation;ements for at least two days and performs estimation;

– Provides stable and accurate estimation in comparison with a realtime Provides stable and accurate estimation in comparison with a realtime sequential processing.sequential processing.

• Data Storage Server:Data Storage Server:– Very large capacity storage with RAID configuration;Very large capacity storage with RAID configuration;

– Holds input measurements and resulted message stream for several mHolds input measurements and resulted message stream for several months (depending on the number of monitor stations).onths (depending on the number of monitor stations).


SSLIDELIDE 2121L1SMS Installed at ENRIL1SMS Installed at ENRI

StorageStorage

Router toRouter toGEONETGEONET

I/FI/F

UPSUPSUPSUPS

MessageMessageGeneratorGenerator

GEONETGEONETServerServer

StorageStorage

Ionosphere Ionosphere ProcessorProcessor

StorageStorage


SSLIDELIDE 2222Configuration of L1SMSConfiguration of L1SMS

GEONET ServerGEONET Server

Ionosphere ProcessorIonosphere ProcessorTroposphere ProcessorTroposphere Processor

Message GeneratorMessage Generator(L1SMG)(L1SMG)

GEONETGEONET

Batch ProcessorBatch Processor(IFB Estimation)(IFB Estimation)

L1SMS Batch SubsystemL1SMS Batch Subsystem

L1SMS Realtime SubsystemsL1SMS Realtime Subsystems

TCP/IPTCP/IP

MessageMessageOutputOutput

via TCP/IPvia TCP/IP

ObservationObservationFile (RINEX)File (RINEX)

via FTPvia FTP

IFBIFBEstimatesEstimates

Primary ReceiverPrimary Receiver

Interface ProcessorInterface Processor

Dual Freq. Ant.Dual Freq. Ant.


SSLIDELIDE 2323Message Generator (L1SMG)Message Generator (L1SMG)

Input ModuleInput Module

L1-SAIF MessageL1-SAIF MessageGenerator (L1SMG)Generator (L1SMG)MessageMessage

OutputOutput

Primary ReceiverPrimary Receiver

Messaging ModuleMessaging Module

Ionospheric CorrectionIonospheric Correction(Standard Planar Fit)(Standard Planar Fit)

GEONET ServerGEONET Server

MessageMessageLogLog

Time andTime andNAV MessageNAV Message

Input fromInput fromIono ProcessorIono Processor

GMS measurementGMS measurement(6 stations)(6 stations)

Clock and OrbitClock and OrbitCorrectionCorrection

Dual Freq. Ant.Dual Freq. Ant.

Ionospheric CorrectionIonospheric CorrectionProcessor (ICP)Processor (ICP)

Input ModuleInput Module

IonosphericIonosphericCorrection ModuleCorrection Module

QUERYQUERY

RESPONSERESPONSE

IMS measurementIMS measurement(200 stations)(200 stations)


SSLIDELIDE 2424Command and ResponseCommand and Response

Variable Bytes Unit

Command Time 8 (double)

Number of IGPs 2 —

IGP 1Latitude 2 0.1 deg

Longitude 2 0.1 deg

:

IGP nLatitude 2 0.1 deg

Longitude 2 0.1 deg

Variable Bytes Unit

Response Time 8 (double)

Number of IGPs 2 —

IGP 1Vertical Delay 8 (double)

GIVE 8 (double)

:

IGP nVertical Delay 8 (double)

GIVE 8 (double)

QUERY CommandQUERY Command RESPONSE MessageRESPONSE Message

• Each command and message is packed with Header and CRC;Each command and message is packed with Header and CRC;

• QUERY command identifies location of each IGP; ICP computes vertical delay QUERY command identifies location of each IGP; ICP computes vertical delay for each IGP location separately; for each IGP location separately;

• If Message Generator could not receive any response from ICP for 150 If Message Generator could not receive any response from ICP for 150 seconds, the command shall be timed out.seconds, the command shall be timed out.


SSLIDELIDE 2525Realtime Operation TestRealtime Operation Test

• Tested performance of the ICP Tested performance of the ICP Implemented as a subsystem of Implemented as a subsystem of L1SMS; running with L1SMG;L1SMS; running with L1SMG;

• Analyzed user position error at 14 Analyzed user position error at 14 evaluation locations; Numbered from evaluation locations; Numbered from North to South;North to South;

• Used GEONET stations as all Used GEONET stations as all monitor stations and evaluation sites.monitor stations and evaluation sites.

GMS Stations (6) for L1SMGGMS Stations (6) for L1SMG

L1-SAIF Experimental AreaL1-SAIF Experimental Area

IMS Station (200) for ICPIMS Station (200) for ICP

Evaluation Locations (14)Evaluation Locations (14)


SSLIDELIDE 2626Results – Position Error SampleResults – Position Error Sample

• Example of user positioning error at Site Example of user positioning error at Site #5 93022 Choshi (East of Tokyo);#5 93022 Choshi (East of Tokyo);

• ICP: 200 IMS, 5-deg IGP, 0th Order Fit;ICP: 200 IMS, 5-deg IGP, 0th Order Fit;

• Period: 16-21 Jan. 2009 (5 days).Period: 16-21 Jan. 2009 (5 days).

MSAS AugmentationMSAS Augmentation

Standalone GPSStandalone GPS

L1-SAIF AugmentationL1-SAIF Augmentation

SystemHorizontal

ErrorVertical Error

L1-SAIFRMS 0.23 m 0.36 m

MAX 1.67 m 3.35 m

MSASRMS 0.46 m 0.59 m

MAX 1.73 m 2.43 m

Standalone GPS

RMS 1.25 m 2.99 m

MAX 4.30 m 8.11 m


SSLIDELIDE 2727Computation TimeComputation Time

Request 42 IGPs (5 deg)Request 42 IGPs (5 deg)

RESPONSERESPONSEMessageMessage

Request 143 IGPs (2.5 deg)Request 143 IGPs (2.5 deg)

16 seconds16 secondsfor 101 IGPsfor 101 IGPs

7 seconds7 secondsfor 42 IGPsfor 42 IGPs

L1SMGL1SMG ICPICP

ConnectionConnectionACKACK

QUERYQUERYCommandCommand

RESPONSERESPONSEMessageMessage

QUERYQUERYCommandCommand

Delay and GIVEDelay and GIVE

Delay and GIVEDelay and GIVE

Cache for 42 IGPsCache for 42 IGPs

Computation TimeComputation Time0.16 s / IGP0.16 s / IGP


SSLIDELIDE 2828Test CasesTest Cases

Case A B C D E MSAS

Ionospheric Correction Made by

L1SMG ICP ICP ICP ICP MSAS

Used Stations 6 GMS 200 IMS 200 IMS 200 IMS 200 IMS 6 GMS

IGP grid 5 deg 5 deg 5 deg 2.5 deg 2.5 deg 5 deg

Estimation Order 1 1 0 1 0 1

Rmax (km) 2100 1000 1000 1000 1000 2100

Nmax 30 30 30 30 30 30

Nmin 10 10 10 10 10 10

• Rmax, Nmax, and Nmin are parameters to select ionospheric pierce point (IPP) Rmax, Nmax, and Nmin are parameters to select ionospheric pierce point (IPP) measurements to be used for estimate the IGP delay;measurements to be used for estimate the IGP delay;

• The ICP collects IPPs within smaller radius because 200 IMS stations provide vaThe ICP collects IPPs within smaller radius because 200 IMS stations provide vast number of measurements.st number of measurements.


SSLIDELIDE 2929Location vs. Horizontal AccuracyLocation vs. Horizontal Accuracy

• ICP improves position accuracy in the Southern Region;ICP improves position accuracy in the Southern Region;• First order estimation is better to ensure accuracy.First order estimation is better to ensure accuracy.


SSLIDELIDE 3030Location vs. Vertical AccuracyLocation vs. Vertical Accuracy

• 1 meter accuracy is achievable even for vertical direction;1 meter accuracy is achievable even for vertical direction;• Note that these results associate with solar minimum phase.Note that these results associate with solar minimum phase.


SSLIDELIDE 3131ConclusionConclusion

• ENRI has been developing QZSS L1-SAIF signal:ENRI has been developing QZSS L1-SAIF signal:– L1-SAIF augmentation signal on GPS/SBAS L1 frequency;L1-SAIF augmentation signal on GPS/SBAS L1 frequency;

– Signal design: upper compatible with SBAS.Signal design: upper compatible with SBAS.

• Development of Ionospheric Correction Processor (ICP):Development of Ionospheric Correction Processor (ICP):– Improves accuracy of WADGPS such as SBAS and L1-SAIF;Improves accuracy of WADGPS such as SBAS and L1-SAIF;

– Implemented as a subsystem of L1-SAIF Master Station; Respond to QUERImplemented as a subsystem of L1-SAIF Master Station; Respond to QUERY command issued from L1-SAIF Message Generator;Y command issued from L1-SAIF Message Generator;

– Achievable accuracy: 0.2-0.3m horizontal at center of Japan; 0.5-0.7m at thAchievable accuracy: 0.2-0.3m horizontal at center of Japan; 0.5-0.7m at the edge of service area; Note: nominal condition of solar minimum phase.e edge of service area; Note: nominal condition of solar minimum phase.

• Future works will include:Future works will include:– Verify the performance during ionospheric storm condition;Verify the performance during ionospheric storm condition;

– Consider other L1-SAIF message formats for ionospheric correction.Consider other L1-SAIF message formats for ionospheric correction.

– Contact: [email protected]: [email protected]

t. sakai, t. yoshihara, s. fukushima, and k. ito electronic navigation research institute, japan

Documents

sbas signal

l1saif signal offers

area augmentation signal

augmentation signals

signal availability

qzss l1saifion itm

gpscompatible l1ca

gps l1ca