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T. Sakai, S. Fukushima, N. Takeichi, and K. Ito Electronic Navigation Research Institute, Japan

ION NTM 2007 San Diego, CA Jan. 22-24, 2007. Augmentation Performance of QZSS L1-SAIF Signal. T. Sakai, S. Fukushima, N. Takeichi, and K. Ito Electronic Navigation Research Institute, Japan. Introduction. QZSS will provide augmentation signals: In addition to supplement signals;

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T. Sakai, S. Fukushima, N. Takeichi, and K. Ito Electronic Navigation Research Institute, Japan

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  1. ION NTM 2007 San Diego, CA Jan. 22-24, 2007 Augmentation Performance of QZSS L1-SAIF Signal T. Sakai, S. Fukushima, N. Takeichi, and K. Ito Electronic Navigation Research Institute, Japan

  2. Introduction • QZSS will provide augmentation signals: • In addition to supplement signals; • L1-SAIF (Submeter-class Augmentation with Integrity Function) on GPS/SBAS L1 frequency and LEX on Galileo E6; • L1-SAIF augmentation signal offers: wide-area differential correction, integrity function, and ranging function. • ENRI is responsible for developing L1-SAIF: • Signal design: identical with SBAS; • Message design is in progress: upper compatible with SBAS. • Performance analysis using prototype SBAS: • Submeter accuracy likely achievable; • Most recently, realtime operation trial has been conducted successfully.

  3. Part 1 Overview of QZSS Program and L1-SAIF Signal

  4. 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

  5. QZSS Signals • Supplement 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 JPO on broadcasting L1C signal; • JAXA is responsible for all supplement signals. • Augmentation signals: • Augmentation to GPS; Possibly plus Galileo; • L1-SAIF (Submeter-class Augmentation with Integrity Function): compatible with SBAS; reasonable performance for mobile users; • LEX: for experimental purposes; member organizations may use as 2kbps experimental data channel; • ENRI is working for L1-SAIF and JAXA is developing LEX.

  6. Frequency Plan Signal Channel Frequency Bandwidth Min. Rx Power QZS-L1C L1CD 1575.42 MHz 24 MHz –163.5 dBW L1CP 24 MHz – 158.4 dBW QZS-L1-C/A 24 MHz – 158.5 dBW QZS-L1-SAIF 24 MHz – 161.0 dBW QZS-L2C 1227.6 MHz 24 MHz – 161.0 dBW QZS-L5 L5I 1176.45 MHz 25 MHz – 157.9 dBW L5Q 25 MHz – 157.9 dBW QZS-LEX 1278.75 MHz 42 MHz – 156.0 dBW Find detail in IS-QZSS document.

  7. L1-SAIF Signal • QZSS will transmit wide-area augmentation signal: • Called L1-SAIF (Submeter-class Augmentation with Integrity Function); • Developed by ENRI (Electronic Navigation Research Institute), Japan. • L1-SAIF signal offers: • Wide-area differential corrections for improving position accuracy; Target accuracy: 1 meter for horizontal; • Integrity function for safety of mobile users; and • Ranging function to improve signal 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 same as SBAS.

  8. L1 PRN Assignment PRN Signal Satellite 183 QZS-L1-SAIF QZS #1 184 QZS-L1-SAIF QZS #2 185 QZS-L1-SAIF QZS #3 186 QZS-L1-SAIF QZS #4 187 QZS-L1-SAIF QZS #5 188 to 192 QZS-L1-SAIF (Reserved) 193 to 197 QZS-L1-C/A QZS #1-5 198 to 202 QZS-L1-C/A (Reserved) Find detail in IS-QZSS document.

  9. SBAS Message Structure Preamble 8 bits Message Type 6 bits Data Field 212 bits CRC parity 24 bits 250 bits MT Contents Interval [s] MT Contents Interval [s] 0 Test mode 6 17 GEO almanac 300 1 PRN mask 120 18 IGP mask 300 2～5 Fast correction & UDRE 60 24 FC & LTC 6 6 UDRE 6 25 Long-term correction 120 7 Degradation factor for FC 120 26 Ionospheric delay & GIVE 300 9 GEO ephemeris 120 27 SBAS service message 300 10 Degradation parameter 120 28 Clock-ephemeris covariance 120 12 SBAS time information 300 63 Null message —

  10. L1-SAIF Message (1) Message Type Contents Compatibility Status 0 Test mode SBAS Fixed 1 PRN mask SBAS Fixed 2 to 5 Fast correction & UDRE SBAS Fixed 6 UDRE SBAS Fixed 7 Degradation factor for FC SBAS Fixed 8 Reserved Unused Fixed 9 GEO ephemeris Unused Fixed 10 Degradation parameter SBAS Fixed 12 SBAS network time Unused Fixed 17 GEO almanac Unused Fixed 18 IGP mask SBAS Fixed 24 Mixed fast/long-term correction SBAS Fixed 25 Long-term correction SBAS Fixed 26 Ionospheric delay & GIVE SBAS Fixed

  11. L1-SAIF Message (2) Message Type Contents Compatibility Status 27 SBAS service message Unused Fixed 28 Clock-ephemeris covariance SBAS Fixed 29 to 51 (Undefined) — — 52 to 55 (Atmospheric correction) New TBD 56 Intersignal biases New Tentative 57 (Ephemeris-related parameter) New TBD 58 QZS ephemeris New Tentative 59 (QZS almanac) New TBD 60 (Regional information) New TBD 61 Reserved New Tentative 62 Reserved SBAS Fixed 63 Null message SBAS Fixed

  12. Messaging Capacity Message Type Messages Required for Constellation Interval Messages per min Fast Correction 2 to 5 3 10 s 18 Long-Term Correction 25 4 60 s 4 Ionosphere 26 2 60 s 2 Troposphere 54 and 55 3 60 s 3 QZS Ephemeris 58 1 30 s 2 FC Degradation 7 1 60 s 1 Degradation Parameter 10 1 60 s 1 PRN Mask 1 1 60 s 1 IGP Mask 18 2 60 s 2 C-E Covariance 28 10 60 s 10 Total 44 Margin for Other Messages 16

  13. Part 2 Performance Analysis Using Prototype SBAS • Prototype SBAS Software • Continuous Daily Operation • Realtime Operation Trial

  14. Performance Analysis • Performance analysis method: • Typical model-based analysis: modeling (differentially corrected) range domain accuracy and projects it into position domain; • For more reliable analysis of the actual performance, we need to simulate MCS algorithms; For example, generating augmentation message enables evaluation of the actual user error; Error-based analysis; • ENRI has developed the prototype SBAS software for investigation of wide-area augmentation technique; This would be a powerful tool working as an MCS simulator. GPS observables User Receiver Simulator Position Error Prototype SBAS (MCS simulator) Augmentation Message

  15. Prototype SBAS • Actually computer software running on PC or UNIX: • ‘RTWAD’ written in C language (not MATLAB, sorry); • Consists of the essential components and algorithms of WADGPS; • Acts as a simulator of SBAS MCS; Parameters are controllable. • Input observables work as monitor stations: • RINEX or raw receiver measurement at any sampling rate; • Requires dual frequency code phase pseudoranges; No carrier phase. • Generates the complete SBAS message stream: • Outputs one message per second; • 250 bps raw message stream before FEC encoding; • Also outputs in NovAtel $FRMA record format is available; for direct input to SBAS user receiver simulator.

  16. Message Sample $FRMA,272,86403.130,183,80811EA4,250,53081FFDFFDFFDFFDFFDFFDFFDFFDFFDFFDFFDFFDFFFBBBBBBBBBBBBAC1CD280*7C $FRMA,272,86404.130,183,80811EA4,250,9A0C1FFDFFDFFDFFDFFDFFDFFDFFDFFDFFDFFDFFDFFFBBBBBBBBBBBBB7E76F80*0F $FRMA,272,86405.130,183,80811EA4,250,C661FFDFFDFFDFFDFFDFFFBBBBB8800000000000000000000000000036CD8A40*70 $FRMA,272,86406.130,183,80811EA4,250,5306FFBFFFF8000000000000000000000000000000000000000000002B963FC0*0D $FRMA,272,86407.130,183,80811EA4,250,9A091FFDFFDFFDFFDFFDFFDFFDFFDFFDFFDFFDFFDFFFBBBBBBBBBBBB806D3340*77 $FRMA,272,86408.130,183,80811EA4,250,C60D1FFDFFDFFDFFDFFDFFDFFDFFDFFDFFDFFDFFDFFFBBBBBBBBBBBB924AAE40*08 $FRMA,272,86409.130,183,80811EA4,250,5361FFDFFDFFDFFDFFDFFFBBBBB89000000000000000000000000000021FE640*73 $FRMA,272,86410.130,183,80811EA4,250,9A61FFDFFDFFDFFDFFDFFFBBBBB8A00000000000000000000000000039994D00*05 $FRMA,272,86411.130,183,80811EA4,250,C60A1FFDFFDFFDFFDFFDFFDFFDFFDFFDFFDFFDFFDFFFBBBBBBBBBBBBA6BE8CC0*03 $FRMA,272,86412.130,183,80811EA4,250,530E1FFDFFDFFDFFDFFDFFDFFDFFDFFDFFDFFDFFDFFFBBBBBBBBBBBBA99E5040*0A Time Message Type ID (6 MSBs) CRC Satellite PRN Preamble Message Length

  17. User Receiver Simulator • SBAS user receiver simulator: • Also software running on PC or UNIX; • Processes RINEX observation file with L1 pseudorange; carrier smoothing applied; • Decodes SBAS message stream (NovAtel $FRMA records) and apply them to the observables based on the SBAS standard; • Outputs position solution in ECEF X, Y, Z; • Verified with WAAS and MSAS messages. • L1-SAIF message stream generated by the prototype was evaluated by this user receiver simulator: • With GEONET observations at some locations as user stations; • Evaluates position accuracies and protection levels of QZSS L1-SAIF.

  18. Standard Configuration GEONET for Monitor Stations GEONET for User Stations MSAS Service Area • At first the prototype generated messages in offline mode with GEONET sites as monitor stations; • Dual frequency observables sampled every 30 seconds; • 6 monitor stations distributed similar to the MSAS; • 5 user locations for evaluation.

  19. Residual of Corrected Orbit Line-of-sight component including clock contribution

  20. Residual of Iono Correction Ionospheric delay minus IGS/IONEX estimation at each IGP

  21. User Position Error Standalone GPS Augmented by the Prototype System Horizontal Error Vertical Error Standalone GPS RMS 1.929 m 3.305 m Max 6.993 m 14.48 m Prototype RMS 0.381 m 0.531 m Max 2.867 m 5.451 m • Example of user positioning error at Site 940058 (Takayama; near center of monitor station network). • Period: 22-24 July 2004; • active ionosphere condition.

  22. Performance Summary Site 2005/11/14-16 2004/7/22-24 2004/6/22-24 2005/11/14-16 MSAS Hor Ver Hor Ver Hor Ver Hor Ver 940030 RMS Max 0.354 1.695 0.418 2.517 0.432 2.318 0.566 4.455 0.397 2.047 0.602 4.717 0.381 1.659 0.631 2.405 North 940058 RMS Max 0.304 1.487 0.413 2.123 0.381 2.867 0.531 5.451 0.425 2.634 0.603 3.466 0.502 4.873 0.728 3.700 940083 RMS Max 0.353 1.902 0.508 4.452 0.403 2.468 0.592 4.240 0.385 1.757 0.649 3.782 0.637 8.517 0.881 9.396 950491 RMS Max 0.453 3.302 0.647 6.158 0.586 2.143 0.764 5.509 0.491 2.415 0.776 4.574 0.640 3.012 0.730 2.680 South 92003 RMS Max 1.132 6.266 1.102 5.958 0800 4.487 1.317 9.225 0.708 4.507 1.088 6.595 0.982 6.267 1.014 6.614 Unit: [m]

  23. Continuous Daily Operation • The prototype has been operated continuously since April: • In order to verify the performance of the prototype for long-term; • Standard configuration: 6 monitor stations distributed similar to the MSAS; and ‘Planar Fit’ ionospheric correction; • Observation files are provided from GEONET at daily basis; • Augmentation output is stored as daily files. • Evaluation at everywhere, everyday: • Evaluated with GEONET stations at 40 locations; covering the whole Japan for testing integrity; • Position accuracy and integrity function are tested everyday. • Messages stored and disclosed at: • URL http://www.enri.go.jp/sat/pro/data/ppwad

  24. Monitor Stations Evaluation Stations Integrity Evaluation Sites • Standard configuration of monitor stations: 6 stations similar to the MSAS; • Integrity evaluation stations: 40 stations covering the whole Japan; • So far, no integrity break conditions have been detected.

  25. Protection Levels vs. Error (1) Horizontal Vertical GEONET 0030 (Oga) 06/4/20 – 06/5/19 (30 days) PPWAD GN/6+S

  26. Protection Levels vs. Error (2) Horizontal Vertical GEONET 0083 (Kochi) 06/4/20 – 06/5/19 (30 days) PPWAD GN/6+S

  27. User Positioning Accuracy GEONET 3011 (Kawagoe; near Tokyo) 06/6/1 – 06/9/30 (4 months) PPWAD GN/6+S 0.3-0.5m Everyday!

  28. Archived Message Stream From 2006/7/3 (day #184) Archived daily 1 file per day Filename: ppwad_YYDDD.log.gz Available at URL http://www.enri.go.jp/sat/pro/data/ppwad

  29. Realtime Operation Trial • Most recently the prototype has capability to run in realtime: • Realtime message generator has been developed; • Realtime input of observables, and realtime output of message stream both via TCP/IP socket connection; • Outputs one message per second each in advance a few seconds to simulate data transmission latency through JAXA-MCS and QZS; • Output message stream is also stored as daily files. • Realtime operation trial: • Realtime observables provided by GEONET online; Standard configuration sites (6 monitor stations, 1 Hz); • Trial period: 2007/1/13 – 1/16 (84 hours); • User positioning accuracy was evaluated with GEONET offline RINEX measurements at user locations.

  30. User Position Error (Realtime) System Horizontal Error Vertical Error Standalone GPS RMS 1.415 m 2.431 m Max 7.059 m 10.47 m Prototype RMS 0.370 m 0.484 m Max 2.610 m 4.713 m Standalone GPS Augmented by the Prototype • Example of user positioning error at Site 940058 (Takayama; near center of monitor station network). • Period: 13-16 Jan. 2007 (84 hours); • Realtime mode.

  31. Site 2007/1/13-16 (84 hours) Hor Ver 940030 Oga RMS Max 0.434 2.739 0.582 5.395 North 940058 Takayama RMS Max 0.370 2.610 0.484 4.713 940083 Kochi RMS Max 0.373 2.769 0.612 4.584 950491 Sata RMS Max 0.701 4.591 0.995 8.042 South 92003 Chichijima RMS Max 1.369 9.964 1.244 11.59 Realtime Performance Unit: [m]

  32. Conclusion • ENRI is developing QZSS L1-SAIF signal: • L1-SAIF augmentation signal on GPS/SBAS L1 frequency; • Signal design: compatible with SBAS; • Message design is in progress: upper compatible with SBAS. • Evaluated using prototype SBAS developed by ENRI: • Submeter accuracy likely achievable; • The result of long-term evaluation is promising; The archive of generated messages is available at: http://www.enri.go.jp/sat/pro/data/ppwad • Realtime operation trial has been conducted successfully. • Future works will include: • Design of L1-SAIF additional messages improving atmospheric corrections; • Stability test and parameter tuning for realtime operation; • Contact: sakai@enri.go.jp

  33. Backup Slides

  34. Prototype I/O Features Monitor Station Observables Input format RINEX OBS/NAV NovAtel OEM-3 Trimble JAVAD Requires dual frequency pseudoranges and C/N0 Sampling rate Any (up to 1Hz) Input device File (offline mode) TCP/IP socket connection (realtime mode) Output format Readable Text Binary NovAtel $FRMA record format Message Stream Output Message rate 1 Hz Output device File (separated daily) TCP/IP socket connection # of monitor stations ≥ 3 stations (upper limit depends on PC) Ionospheric correction Planar fit (identical to WAAS/MSAS)

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