Recent Development of QZSS L1-SAIF Master Station ION ITM 2010 San Diego, CA Jan. 25-27, 2010 Recent Development of QZSS L1-SAIF Master Station T. Sakai, S. Fukushima, and K. Ito Electronic Navigation Research Institute, Japan

Introduction QZSS (Quasi-Zenith Satellite System) program: ION ITM 25-27 Jan. 2010 - ENRI Introduction QZSS (Quasi-Zenith Satellite System) program: Regional navigation service broadcast from high-elevation angle by three satellites on the inclined geosynchronous (quasi-zenith) orbit; Currently working for launch of the first satellite in 2010 Summer season; Broadcast GPS-compatible supplemental signals on three frequencies and two augmentation signals, L1-SAIF and LEX. L1-SAIF (Submeter-class Augmentation with Integrity Function) signal offers: Sub-meter accuracy wide-area differential correction service; Integrity function for safety of mobile users; and Ranging function for position availability; all on L1 single frequency. ENRI has been developing L1-SAIF signal and facility: Signal design: GPS/SBAS-compatible on L1; Implemented L1-SAIF Master Station (L1SMS) which generates augmentation message stream in realtime and transmits it to QZSS MCS.

Overview of QZSS Program ION ITM 25-27 Jan. 2010 - ENRI Part 1 Overview of QZSS Program

QZSS Concept Signal from high elevation angle ION ITM 25-27 Jan. 2010 - ENRI QZSS Concept QZS GPS/GEO Signal from high elevation angle Applicable to navigation services for mountain area and urban canyon Footprint of QZS orbit Centered 137E Eccentricity 0.1, Inclination 45deg

QZSS Program QZSS (Quasi-Zenith Satellite System) program: ION ITM 25-27 Jan. 2010 - ENRI QZSS Program QZSS (Quasi-Zenith Satellite System) program: Japan has been developing QZSS since FY 2003; Regional navigation service broadcast from high-elevation angle by three satellites on the inclined geosynchronous (quasi-zenith) orbit; Broadcast GPS-compatible supplemental signals on three frequencies (L1 C/A, L1C, L2C, and L5) and two augmentation signals, L1-SAIF and LEX. Participating institutes: JAXA (Japan Aerospace Exploration Agency): Development and operation of the space segment and Master Control Station; NICT (National Institute of Information and Communication Technology): Frequency standard and time keeping system including Uplink Station; AIST (National Institute of Advanced Industrial Science and Technology): Time synch-ronization between space and ground; GSI (Geographical Survey Institute): Survey-grade carrier-based positioning service; ENRI (Electronic Navigation Research Institute): Navigation-grade WADGPS service broadcast by L1-SAIF signal.

Overall Architecture GPS Satellites QZS Satellite User Receiver ION ITM 25-27 Jan. 2010 - ENRI Overall Architecture Function distributed in each institute Timing management by NICT, WADGPS service by ENRI, etc. SLR Site Monitor 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 Satellite Laser Ranging Navigation Signals L1: 1575.42 MHz L2: 1227.60 MHz L5: 1176.45 MHz LEX: 1278.75 MHz TT&C / NAV Message Uplink TWSTFT Up: 4.43453GHz Down: 12.30669GHz (Courtesy: JAXA QZSS PT) Master Control Station (MCS)

Space Segment: QZS-1 25.3m L1-SAIF Antenna ION ITM 25-27 Jan. 2010 - ENRI Space Segment: QZS-1 L-band Helical Array Antenna L1-SAIF Antenna Laser Reflector C-band TTC Antenna Radiation Cooled TWT TWSTFT Antenna 25.3m Mass Approx. 1,800kg (dry) (NAV Payload：Approx. 320kg) Power Approx. 5.3 kW (EOL) (NAV Payload: Approx. 1.9kW) Design Life 10 years

QZSS Signals Supplemental signals: Augmentation signals: ION ITM 25-27 Jan. 2010 - ENRI QZSS Signals Supplemental signals: GPS-compatible L1C/A, L2C, L5, and L1C signals working with GPS; For improving availability of navigation; With minimum modifications from GPS signal specifications; Coordination with GPS Wing on broadcasting L1C signal; JAXA is responsible for all supplemental signals. Augmentation signals: Augmentation to GPS; Possibly plus Galileo; L1-SAIF: Compatible with SBAS; reasonable performance for mobile users; LEX: For carrier-based experimental purposes; member organizations may use as 2kbps experimental data channel; ENRI is working for L1-SAIF while JAXA is developing LEX. Interface Specification: IS-QZSS: Specifies RF signal interface between QZS satellite and user receiver; First issue: Jan. 2007; Maintained by JAXA.

QZSS Frequency Plan Signal Channel Frequency Bandwidth Min. Rx Power ION ITM 25-27 Jan. 2010 - ENRI QZSS Frequency Plan Signal Channel Frequency Bandwidth Min. Rx Power QZS-L1C L1CD 1575.42 MHz 24 MHz –163.0 dBW L1CP – 158.25 dBW QZS-L1-C/A – 158.5 dBW QZS-L1-SAIF – 161.0 dBW QZS-L2C 1227.6 MHz – 160.0 dBW QZS-L5 L5I 1176.45 MHz 25 MHz – 157.9 dBW L5Q QZS-LEX 1278.75 MHz 42 MHz – 155.7 dBW Find detail in IS-QZSS document.

ION ITM 25-27 Jan. 2010 - ENRI Part 2 L1-SAIF Signal Design

QZSS L1-SAIF Signal QZSS will broadcast wide-area augmentation signal: ION ITM 25-27 Jan. 2010 - ENRI QZSS L1-SAIF Signal QZSS will broadcast wide-area augmentation signal: Called L1-SAIF (Submeter-class Augmentation with Integrity Function); Developed by ENRI. L1-SAIF signal offers: Wide-area differential correction service for improving position accuracy; Target accuracy: 1 meter for horizontal; Integrity function for safety of mobile users; and Ranging function for position availability. Interoperable with GPS L1C/A and fully compatible with SBAS: Broadcast on L1 freq. with RHCP; Common antenna and RF front-end; Modulated by BPSK with C/A code; 250 bps data rate with 1/2 FEC; message structure is identical with SBAS; Differences: Large Doppler and additional messages.

WADGPS Concept Clock Correction Ionospheric Correction ION ITM 25-27 Jan. 2010 - ENRI WADGPS Concept Orbit Correction Troposphere Ionosphere Ionospheric Correction Tropospheric Correction Clock Correction Same contribution to any user location; Not a function of location; Needs fast correction. Different contribution to different user location; Not a function of user location; but a function of line-of-sight direction; Long-term correction. Function of user location; Up to 100 meters; Vertical structure may be described as a thin shell. Function of user location, especially height of user; Up to 20 meters; Can be corrected enough by a fixed model.

SBAS/L1-SAIF Message Structure ION ITM 25-27 Jan. 2010 - ENRI SBAS/L1-SAIF Message Structure Preamble 8 bits Message Type 6 bits Data Field 212 bits CRC parity 24 bits 250 bits per second MT 1 2～5 6 7 9 10 12 17 18 Contents Test mode PRN mask Fast correction & UDRE UDRE Degradation factor for FC GEO ephemeris Degradation parameter SBAS time information GEO almanac IGP mask Interval [s] 120 60 300 24 25 26 27 28 63 FC & LTC Long-term correction Ionospheric delay & GIVE SBAS service message Clock-ephemeris covariance Null message — Transmitted First

SBAS/L1-SAIF Message (1) ION ITM 25-27 Jan. 2010 - ENRI SBAS/L1-SAIF Message (1) Message Type Contents Compatibility Status Test mode Both Fixed 1 PRN mask 2 to 5 Fast correction & UDRE 6 UDRE 7 Degradation factor for FC 10 Degradation parameter 18 IGP mask 24 Mixed fast/long-term correction 25 Long-term correction 26 Ionospheric delay & GIVE 9 GEO ephemeris SBAS 17 GEO almanac 12 SBAS network time 8 Reserved

SBAS/L1-SAIF Message (2) ION ITM 25-27 Jan. 2010 - ENRI SBAS/L1-SAIF Message (2) Message Type Contents Compatibility Status 27 SBAS service message SBAS Fixed 29 to 51 (Undefined) — 28 Clock-ephemeris covariance Both 62 Reserved 63 Null message 52 TGP mask L1-SAIF Tentative 56 Intersignal biases 57 (Ephemeris-related parameter) TBD 58 QZS ephemeris 59 (QZS almanac) 60 (Regional information) 61 5３ Tropospheric delay 54 to 55 (Advanced Ionospheric delay)

GPS/L1-SAIF Simulator GPS/L1-SAIF Simulator: ION ITM 25-27 Jan. 2010 - ENRI GPS/L1-SAIF Simulator GPS/L1-SAIF Simulator: Simulates GPS L1 C/A and QZSS L1-SAIF signals; Generates RF signals based on pre-defined GPS and QZSS constellation scenario and signal specifications of IS-GPS and IS-QZSS; Manufactured by Spirent, modifying GPS/SBAS simulator GSS7700. Special function for experiment: Added extra command to input L1-SAIF message from Ethernet port (TCP/IP); L1-SAIF message is either input by the command externally or generated by the simulator internally. GPS/L1-SAIF Simulator Receiver

GPS/L1-SAIF Receiver Prototype GPS/L1-SAIF Receiver: ION ITM 25-27 Jan. 2010 - ENRI GPS/L1-SAIF Receiver Prototype GPS/L1-SAIF Receiver: Receives GPS L1 C/A and QZSS L1-SAIF signals; Decode and apply L1-SAIF message as defined by IS-QZSS; Manufactured by Furuno Electric. Special function for experiment: L1-SAIF message can be input from Ethernet port (TCP/IP)　as well as L1-SAIF signal on RF; Enable to process L1-SAIF and SBAS, totally three, augmentation signals simultaneously; Portable equipage for experiment at remote or on mobile. GPS/L1-SAIF Receiver

RF Compatibility Test GPS/L1-SAIF Simulator Receiver TCP/IP RF Cable ION ITM 25-27 Jan. 2010 - ENRI RF Compatibility Test GPS/L1-SAIF Simulator Receiver TCP/IP RF Cable Spirent Furuno Electric File L1-SAIF Message Scenario Decoded Message Compare L1-SAIF Signal ENRI (Chofu, Tokyo) Ranging function: The receiver output the proper position solution with pseudorange of L1-SAIF signal generated by the simulator; Decoding message: The receiver decoded L1-SAIF message which matched with the message input to the simulator via Ethernet port; The command needs to be given 2-second before the applicable time of transmission; Successfully completed in Feb. 2009.

RF Compatibility Test OK! 2008/9/10 00:05:00 to 06:00:00 (6 hours) ION ITM 25-27 Jan. 2010 - ENRI RF Compatibility Test 2008/9/10 00:05:00 to 06:00:00 (6 hours) Standalone GPS L1-SAIF Augmentation OK!

L1-SAIF Master Station (L1SMS) ION ITM 25-27 Jan. 2010 - ENRI Part 3 L1-SAIF Master Station (L1SMS)

ENRI L1SMS L1-SAIF Master Station (L1SMS): GSI ENRI JAXA ION ITM 25-27 Jan. 2010 - ENRI ENRI L1SMS L1-SAIF Master Station (L1SMS): Generates L1-SAIF message stream in realtime and transmits it to QZSS MCS developed by and installed at JAXA; Installed at ENRI, Tokyo; 90km from JAXA Tsukuba Space Center; Subsystems: GEONET Server, Primary Receiver, Interface Processor, Message Generator, Ionosphere Processor, Troposphere Processor, and Batch Processor. L1SMS GEONET QZS QZSS MCS GPS Measured Data L1-SAIF Message GSI ENRI JAXA L1-SAIF Signal L1C/A, L2P K-band Closed Loop

L1SMS Installed at ENRI Storage Router to GEONET I/F UPS Message ION ITM 25-27 Jan. 2010 - ENRI L1SMS Installed at ENRI Storage Router to GEONET I/F UPS Message Generator Server Ionosphere Processor

Configuration of L1SMS GEONET Server Ionosphere Processor ION ITM 25-27 Jan. 2010 - ENRI Configuration of L1SMS GEONET Server Ionosphere Processor Troposphere Processor Message Generator (L1SMG) GEONET Batch Processor (IFB Estimation) L1SMS Batch Subsystem L1SMS Realtime Subsystems TCP/IP Message Output via TCP/IP Observation File (RINEX) via FTP IFB Estimates Primary Receiver Interface Processor Dual Freq. ANT

JAXA-ENRI Interface (G-ICD) ION ITM 25-27 Jan. 2010 - ENRI JAXA-ENRI Interface (G-ICD) Ground System ICD (Interface Control Document): Defines interface between JAXA QZSS MCS and ENRI L1SMS; First issue: Jan. 2008; Specifies data stream on TCP/IP connection bit-by-bit. Dual communication lines for redundancy: ISDN (64kbps) and optical (1.5Mbps) links; Low-rate ISDN: Reliable transmission for uploading L1-SAIF message; High-rate optical link: Exchange station status and monitor station observation; Only for the experiment; no definition of service levels. L1SMS MCS A MCS B Router ISDN Optical Upload Message Other Data JAXA ENRI

JAXA-ENRI Interface (G-ICD) ION ITM 25-27 Jan. 2010 - ENRI JAXA-ENRI Interface (G-ICD) Packet ID Contents Direction Link Interval 0xC0 Upload Message L1SMS -> MCS ISDN 1 s 0xC1 Upload Message Echo L1SMS <- MCS 0x02 SMS Status Optical 5 s 0xE2 GPS/QZS Observation 0xE4 GPS Observation 0xE1 Monitor Station Status 0x11 Telemetry Command L1SMS <-> MCS N/A 0x12 Telemetry Data min 1 s 0x01 Experiment Status 10 s 0x21 Orbit and Clock 30 s

Closed-Loop Interface Test ION ITM 25-27 Jan. 2010 - ENRI Closed-Loop Interface Test HUB LAN Upload Message JAXA ENRI Log MCS B Navigation Payload EM RF Cable L1-SAIF Signal L1SMS Simulator NEC (Fuchu, Tokyo) GPS/L1-SAIF Receiver L1SMS Sim Nav payload Receiver Interface test between JAXA MCS and ENRI L1SMS and between Nav payload and receiver; Checked the format of transmitted and received data packets, then compared log files bit-by-bit; Successfully completed in Dec. 2008.

JAXA-ENRI Interface Test ION ITM 25-27 Jan. 2010 - ENRI JAXA-ENRI Interface Test L1SMS Simulator Router ISDN Optical Upload Message Other Data JAXA ENRI Log MCS A MCS B ENRI (Chofu, Tokyo) JAXA (Tsukuba) Interface test between two facilities, JAXA MCS and ENRI L1SMS, with the complete configuration of communication lines; Confirmed the format of transmitted and received data packets, then compared log files taken at both facilities bit-by-bit; Successfully completed in Jan. 2010.

Realtime Operation Test ION ITM 25-27 Jan. 2010 - ENRI Part 4 Realtime Operation Test

Realtime Operation Test ION ITM 25-27 Jan. 2010 - ENRI Realtime Operation Test GMS Stations (6) for L1SMG L1-SAIF Experimental Area IMS Station (200) for ICP Evaluation Locations (14) Tested performance of the ICP Implemented as a subsystem of L1SMS; running with L1SMG; Analyzed user position error at 14 evaluation locations; Numbered from North to South; Used GEONET stations as all monitor stations and evaluation sites.

Results – Position Error Sample ION ITM 25-27 Jan. 2010 - ENRI Results – Position Error Sample MSAS Augmentation Standalone GPS L1-SAIF Augmentation Example of user positioning error at Site #5 93022 Choshi (East of Tokyo); ICP: 200 IMS, 5-deg IGP, 0th Order Fit; Period: 16-21 Jan. 2009 (5 days). System HorizontalError Vertical Error L1-SAIF RMS 0.23 m 0.36 m MAX 1.67 m 3.35 m MSAS 0.46 m 0.59 m 1.73 m 2.43 m Standalone GPS 1.25 m 2.99 m 4.30 m 8.11 m

Location vs. Horizontal Accuracy ION ITM 25-27 Jan. 2010 - ENRI Location vs. Horizontal Accuracy ICP improves position accuracy in the Southern Region; First order estimation is better to ensure accuracy.

Location vs. Vertical Accuracy ION ITM 25-27 Jan. 2010 - ENRI Location vs. Vertical Accuracy 1 meter accuracy is achievable even for vertical direction; Note that these results associate with solar minimum phase.

Realtime Operation Using GEO ION ITM 25-27 Jan. 2010 - ENRI Realtime Operation Using GEO ETS-VIII satellite: Engineering Test Satellite for mobile communication and onboard clock of navigation-grade; Geostationary satellite with very large (19m) folding antenna; Launched in Dec. 2006 by JAXA. ENRI joined the experiment: Communication experiment between two fixed points; L1SMG transmitted L1-SAIF message to ETS-VIII; Received L1-SAIF message was input to the GPS/L1-SAIF receiver and processed properly; Successfully completed in Feb. 2009. ETS-VIII Satellite

Uplink from Tokyo ETS-VIII Satellite Ethernet L1-SAIF message ION ITM 25-27 Jan. 2010 - ENRI Uplink from Tokyo ETS-VIII Satellite Ethernet L1-SAIF message L1-SAIF Master Station RF signal ETS-VIII Terminal Equipment SATCOM Antenna

Downlink to Sendai GPS signal L1-SAIF message ETS-VIII Satellite ION ITM 25-27 Jan. 2010 - ENRI Downlink to Sendai GPS signal L1-SAIF message ETS-VIII Satellite RF signal Ethernet GPS/L1-SAIF Receiver SATCOM Antenna (400km away from Tokyo) ETS-VIII Terminal Equipment

L1-SAIF Receiver Output ION ITM 25-27 Jan. 2010 - ENRI L1-SAIF Receiver Output 2009/2/17 01:21:39 to 07:23:14 (6 hours) Standalone GPS L1-SAIF Augmentation H Error RMS = 1.221m V Error RMS = 4.043m H Error RMS = 0.412m V Error RMS = 0.464m

Resulted User Position Accuracy at Some Locations [unit: m] ION ITM 25-27 Jan. 2010 - ENRI Stability Test Runs L1SMG for several months: To investigate stability of the software implemented in L1SMG; Period I: 2008/3/11 to 2008/5/24 (74 days); Period II: 2008/6/10 to 2008/8/28 (79 days). Result: No major trouble: The software runs for the periods without human interaction; User position accuracy was reasonable. Resulted User Position Accuracy at Some Locations [unit: m] Site 940030 Oga 93101 Omaezaki 940058 Takayama 940085 Tosashimizu 950491 Sata Period I Hor 0.362 0.363 0.423 0.502 Ver 0.517 0.536 0.548 0.608 0.739 Period II 0.460 0.440 0.347 0.416 0.552 0.657 1.236 0.678 0.699 1.371

Conclusion ENRI has been developing L1-SAIF signal: Completed, so far: ION ITM 25-27 Jan. 2010 - ENRI Conclusion ENRI has been developing L1-SAIF signal: Signal design: GPS/SBAS-compatible; Implemented L1-SAIF Master Station (L1SMS) which generates augmentation message stream in realtime and transmit it to QZSS MCS. Completed, so far: Design of L1-SAIF signal and publishing as a part of IS-QZSS; Development of GPS/L1-SAIF simulator and receiver; Development of G-ICD between L1SMS and QZSS MCS, and interface test of them; Interface test at the closed-loop configuration including L1SMS, MCS, QZSS navigation payload, and GPS/L1-SAIF receiver; Realtime operation test with/without geostationary satellite (ETS-VIII); and Stability test of L1SMS. Currently working for: Final interface test at the full-configuration of ground/space systems; Preparation of performance experiment with the first QZS space vehicle.