QZSS (quasi-zenith satellite system) is a Japanese satellite navigation program with a regional service coverage. The orbits for QZS are 24-hour elliptic orbit inclined 45 degrees in order to broadcast radiosignals from high elevation angle into urban canyons. The first QZSS satellite was launched successfully on 11th Sept. 2010 from Tanegashima Space Center, Japan. QZSS will broadcast GPS augmentation information as well as ranging signals on the GPS L1 frequency. For this purpose L1-SAIF (submeter-class augmentation with integrity function) signal has been developed by the ENRI. L1-SAIF augmentation messages are generated at L1-SAIF Master Station (L1SMS) and broadcast to the experimental area via QZSS. All facilities including L1SMS and QZSS master control station have been installed properly and completed integration test. The experiment with the first QZSS satellite will begin after functional checkout by the end of November.

SummarySummary

Development of QZSS L1-SAIF Augmentation Signal

Takeyasu SAKAI, Sonosuke FUKUSHIMA, and Ken ITOElectronic Navigation Research Institute

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•Footprint of QZS orbitFootprint of QZS orbit

•Centered 137ECentered 137E•Eccentricity 0.1, Inclination 45degEccentricity 0.1, Inclination 45deg

QZSS Concept: Navigation signal from high elevation angle

Function distributed in each institute

Timing management by NICT, WADGPS service by ENRI, etc.

SLR SiteMonitor Station NW

GPS Satellites

TT&C / NAV Msg Uplink Station

GEONET(GSI)

Time Mgmt Station

TWSTFT: Two Way Satellite Time and Frequency Transfer

QZS Satellite

User Receiver

SatelliteLaser Ranging

Navigation SignalsL1: 1575.42 MHzL2: 1227.60 MHzL5: 1176.45 MHzLEX: 1278.75 MHz

TT&C / NAV Message Uplink

TWSTFTUp: 4.43453GHz

Down: 12.30669GHz

(Courtesy: JAXA QZSS PT)

Master Control Station (MCS)

Overall Architecture

L-band Helical Array Antenna

L1-SAIF Antenna

Laser Reflector

C-band TTC Antenna

Radiation Cooled TWTTWSTFT Antenna

25.3m

MassApprox. 4,000kg (NAV Payload ： Approx. 320kg)

PowerApprox. 5.3 kW (EOL) (NAV Payload: Approx. 1.9kW)

Design Life 10 years

(c) 三菱重工業

QZS-1 Satellite “Michibiki”

• Successfully Launched at 20:17 of Sept. 11, 2010 from Tanegashima Space Center;• Now initial checkout in progress; First navigation signals successfully broadcast since Oct. 19.

Storage

Router toGEONET

I/F

UPSUPS

MessageGenerator

GEONETServer

Storage

Ionosphere Processor

Storage

L1-SAIF Master Station (L1SMS) at ENRI

With L1-SAIFGPS only

UserReceivers

• L1-SAIF (Submeter-class Augmentation with Integrity Function) augmentation signal provides:

(1) Differential Correction information improving position accuracy; Target accuracy = 1 m;

(2) Integrity information for ensuring reliability of position information;

(3) An additional ranging source to improve availability of satellite constellation.

• User receiver do not need additional antenna and/or RF circuit to receive L1-SAIF signal due to its compatibility with the GPS signal;

• ENRI has been involved the program and developing L1-SAIF.

L1-SAIFRanging

L1-SAIFCorrection

L1-SAIFIntegrity

QZS satelliteGPS Satellites

RangingSignal

L1-SAIF Augmentation Signal

• User position error measured at GEONET site 40058 (Takayama at the center of Mainland of Japan);

• Period: Jan. 19 to 23, 2008 (5 days).

HorizontalError

VerticalError

1.45 m 2.92 m

6.02 m 8.45 m

System

GPS Only

0.29 m 0.39 m

1.56 m 2.57 m

Augmented byL1-SAIF

RMS

Max

RMS

Max

NOTE: This result is obtained by the survey grade antenna and receiver.

L1SMS Realtime Operation Test Result