T. Sakai, H. Yamada, and K. Ito Electronic Navigation Research Institute, Japan T. Sakai, H. Yamada, and K. Ito Electronic Navigation Research Institute, Japan Ranging Quality of QZSS L1-SAIF Signal Ranging Quality of QZSS L1-SAIF Signal ION ITM 2012 Newport Beach, CA Jan.30 - Feb.1, 2012

ION ITM 30 Jan.-1 Feb ENRI S LIDE 1Introduction QZSS (Quasi-Zenith Satellite System) program:QZSS (Quasi-Zenith Satellite System) program: –Regional navigation service broadcast from high-elevation angle by a combination of three satellites on the inclined geosynchronous (quasi-zenith) orbit; –Broadcast GPS-like supplemental signals on three frequencies and two augmentation signals, L1-SAIF and LEX; –The first QZS satellite was successfully launched on Sept. 11, L1-SAIF (Submeter-class Augmentation with Integrity Function) signal offers:L1-SAIF (Submeter-class Augmentation with Integrity Function) signal offers: –Submeter accuracy wide-area differential correction service; –Integrity function for safety of mobile users; and –Ranging function for improving position availability; all on L1 single frequency. ENRI has been developing L1-SAIF signal and experimental facility:ENRI has been developing L1-SAIF signal and experimental facility: –Signal design: SBAS-like message stream on L1 C/A code (PRN 183); –Ranging function is now available: Ephemeris information has been broadcast during the experiments conducted by ENRI since Nov. 2011; –Investigated ranging quality of L1-SAIF signal.  Expect comparable to GPS thanks to signal bandwidth of 24 MHz.

ION ITM 30 Jan.-1 Feb ENRI S LIDE 2 QZSS Concept Broadcast signal from high elevation angle;Broadcast signal from high elevation angle; Applicable to navigation services for mountain area and urban canyon;Applicable to navigation services for mountain area and urban canyon; Augmentation signal from the zenith could help users to acquire other GPS satellites at any time.Augmentation signal from the zenith could help users to acquire other GPS satellites at any time. Footprint of QZSS orbit;Footprint of QZSS orbit; Centered at 135E;Centered at 135E; Eccentricity 0.075, Inclination 43deg.Eccentricity 0.075, Inclination 43deg. QZS GPS/GEO

ION ITM 30 Jan.-1 Feb ENRI S LIDE 3 Inclined Geosynchronous Orbit Ground Track Semi-major axis (42164km) is equal to GEO orbit: synchronous with rotation of the earth;Semi-major axis (42164km) is equal to GEO orbit: synchronous with rotation of the earth; Inclined obit makes ground track ‘8’-figure; Called IGSO or Quasi-Zenith Orbit;Inclined obit makes ground track ‘8’-figure; Called IGSO or Quasi-Zenith Orbit; With three or more satellites on the same ground track, navigation service can be provided from the zenith to regional users at any time.With three or more satellites on the same ground track, navigation service can be provided from the zenith to regional users at any time. Orbital Planes of QZSS (3 SVs) 8:40 15:20 Perigee 32000km Apogee40000km

ION ITM 30 Jan.-1 Feb ENRI S LIDE 4 L-band Helical Array Antenna L1-SAIF Antenna Laser Reflector C-band TTC Antenna Radiation Cooled TWT TWSTFT Antenna 25.3m Successfully launched on Sept. 11, 2010 and settled on Quasi- Zenith Orbit (IGSO). Nickname: “Michibiki” Space Segment: QZS-1 Mass 4,020kg (wet) 1,802kg (dry) (NAV Payload ： 320kg) Power Approx. 5.3 kW (EOL) (NAV Payload: Approx. 1.9kW) Design Life10 years

ION ITM 30 Jan.-1 Feb ENRI S LIDE 5 QZSS Frequency Plan Find detail in IS-QZSS document. SignalChannelFrequencyBandwidth Min. Rx Power QZS-L1CL1CD MHz 24 MHz –163.0 dBW L1CP 24 MHz – dBW QZS-L1-C/A 24 MHz – dBW QZS-L1-SAIF 24 MHz – dBW QZS-L2C MHz 24 MHz – dBW QZS-L5L5I MHz 25 MHz – dBW L5Q 25 MHz – dBW QZS-LEX MHz 42 MHz – dBW Interoperability GPS-like supplemental signals with minimum modifications from GPS signals SBAS-like augmentation signal (250bps) QZSS-specific augmenta- tion signal (2kbps) MHz

ION ITM 30 Jan.-1 Feb ENRI S LIDE 6 QZSS broadcasts wide-area augmentation signal:QZSS broadcasts wide-area augmentation signal: –Called L1-SAIF (Submeter-class Augmentation with Integrity Function); –Designed and developed by ENRI. L1-SAIF signal offers: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 improving position availability. Augmentation to GPS L1C/A based on SBAS techniques:Augmentation to GPS L1C/A based on SBAS techniques: –Broadcast on L1 freq. with RHCP; Common antenna and RF front-end;  Modulated by BPSK with C/A code (PRN 183);  250 bps data rate with 1/2 FEC; message structure is identical with SBAS;  Differences: Large Doppler and additional messages. –Specification of L1-SAIF: See IS-QZSS document (Available at JAXA HP). QZSS L1-SAIF Signal

ION ITM 30 Jan.-1 Feb ENRI S LIDE 7 L1-SAIF Signal User GPS Receivers Three functions by a single signal: ranging, error correction (Target accuracy: 1m), and integrity;Three functions by a single signal: ranging, error correction (Target accuracy: 1m), and integrity; User receivers can receive both GPS and L1-SAIF signals with a single antenna and RF front-end;User receivers can receive both GPS and L1-SAIF signals with a single antenna and RF front-end; Message-oriented information transmission: flexible contents.Message-oriented information transmission: flexible contents. SAIF ： Submeter-class Augmentation with Integrity Function RangingFunction ErrorCorrection IntegrityFunction QZS satellites GPS Constellation Ranging Signal

ION ITM 30 Jan.-1 Feb ENRI S LIDE 8 L1-SAIF Corrections Example of user position error at Site (Takayama: near center of monitor station network);Example of user position error at Site (Takayama: near center of monitor station network); Realtime operation with MSAS-like 6 monitor stations;Realtime operation with MSAS-like 6 monitor stations; Period: Jan (5 days);Period: Jan (5 days); L1-SAIF provides corrections only;L1-SAIF provides corrections only; No L1-SAIF ranging. HorizontalErrorVerticalError 1.45 m 2.92 m 6.02 m 8.45 m System StandaloneGPS 0.29 m 0.39 m 1.56 m 2.57 m L1-SAIF RMS Max RMS Max Note: Results shown here were obtained with survey- grade antenna and receiver in open sky condition. Standalone GPS Augmented by L1-SAIF No L1-SAIF Ranging

ION ITM 30 Jan.-1 Feb ENRI S LIDE 9 Usage of L1-SAIF Ranging Ranging function of L1-SAIF signal:Ranging function of L1-SAIF signal: –RF signal design: Identical with GPS L1 C/A modulated by PRN 183 code; –Necessary to broadcast ephemeris information in order to make ranging function available to users.  L1-SAIF extended message of Type 58 Ephemeris Information is designed for this purpose. Completed L1-SAIF Master Station (L1SMS) upgrade:Completed L1-SAIF Master Station (L1SMS) upgrade: –To be capable of broadcasting MT58 Ephemeris Information during the experiments conducted by ENRI; –Using JAXA monitor stations for generation of MT58. Investigation of ranging quality including effects of Ephemeris Information:Investigation of ranging quality including effects of Ephemeris Information: –RF quality: Expect comparable to GPS thanks to signal bandwidth of 24MHz; –How about quality of ephemeris information on L1-SAIF ? –User receiver setup:  JAVAD ALPHA-G3T with QZSS extension;  Output pseudorange measurements are processed by ENRI;  5 deg Elevation Mask, 100 seconds Carrier Smoothing.

ION ITM 30 Jan.-1 Feb ENRI S LIDE 10 L1-SAIF Message Structure Preamble 8 bits Message Type 6 bits Data Field 212 bits CRC parity 24 bits 1 message = 250 bits broadcast every second MT to 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] FC & LTC Long-term correction Ionospheric delay & GIVE SBAS service message Clock-ephemeris covariance Null message — MTContentsInterval[s] Transmitted First

ION ITM 30 Jan.-1 Feb ENRI S LIDE 11 L1-SAIF Message (1) Message Type Contents Used by Status 0 Test mode SBAS and L1-SAIF Fixed 1 PRN mask Fixed 2 to 5 Fast correction & UDRE Fixed 6UDREFixed 7 Degradation factor for FC Fixed 10 Degradation parameter Fixed 18 IGP mask Fixed 24 Mixed fast/long-term correction Fixed 25 Long-term correction Fixed 26 Ionospheric delay & GIVE Fixed 9 GEO ephemeris SBAS Fixed 17 GEO almanac SBASFixed 12 SBAS network time SBASFixed SBAS and L1-SAIF 8ReservedSBASFixed

ION ITM 30 Jan.-1 Feb ENRI S LIDE 12 L1-SAIF Message (2) Message Type Contents Used by Status 27 SBAS service message SBASFixed 29 to 51 Undefined—— 28 Clock-ephemeris covariance SBAS and L1-SAIF Fixed 62Reserved Fixed 63 Null message SBAS and L1-SAIF Fixed 52 TGP mask L1-SAIFTentative 56 Intersignal biases L1-SAIFTentative 57 Ephemeris-related parameter L1-SAIFTBD 58 QZS ephemeris L1-SAIFTentative 59 QZS almanac L1-SAIFTBD 60 Regional information L1-SAIFTBD 61ReservedL1-SAIFTentative 53 Tropospheric delay L1-SAIFTentative 54 to 55 Advanced Ionospheric delay L1-SAIFTBD

ION ITM 30 Jan.-1 Feb ENRI S LIDE 13 L1-SAIF Ephemeris (MT58) ItemBitsRangeResolutionContents t 0,Q s60 sEpoch time/IODN URA Accuracy indicator x 26  km 1.28 mPosition X in ECEF y 26  km 1.28 mPosition Y in ECEF z 26  km 1.28 mPosition Z in ECEF vx 24  km/s 0.5 mm/sVelocity X in ECEF vy 24  km/s 0.5 mm/sVelocity Y in ECEF vz 24  km/s 0.5 mm/sVelocity Z in ECEF 5  32  m/s 2 2  m/s 2 Acceleration X in ECEF (only perturbation) 5  32  m/s 2 2  m/s 2 Acceleration Y in ECEF (only perturbation) 5  32  m/s 2 2  m/s 2 Acceleration Z in ECEF (only perturbation) a Gf0 22  ms sClock correction, offset a Gf1 13  ns/s s/sClock correction, drift Total212Stored in 1 message (1sec) x y z......

ION ITM 30 Jan.-1 Feb ENRI S LIDE 14 Generation of Ephemeris Ephemeris information is generated based on reconstruction from MCS products broadcast on QZS-L1-C/A (PRN 193):Ephemeris information is generated based on reconstruction from MCS products broadcast on QZS-L1-C/A (PRN 193):  L1SMS receives L1 C/A Nav message and extract QZS-1 PVA for generation of MT58. Users do not need to receive any signals other than L1-SAIF (PRN 183). Users do not need to receive any signals other than L1-SAIF (PRN 183). Decodeephemeris ComputePVA Format into MT58 QZS-L1C/A (PRN 193) Ephemeris in Legacy Nav L1-SAIF (PRN 183) Ephemeris in MT58 L1-SAIF Master Station (L1SMS) at ENRI JAXA MCS QZS-L1C/A Uplink Ephemeris Reconstruction L1-C/A Users L1-SAIF Users QZS-1 No need to receive QZS-L1-C/A (PRN 193)

ION ITM 30 Jan.-1 Feb ENRI S LIDE 15 SV Position Error of MT58 Integration error in user receiver with regard to time after broadcast of MT58 with LTC (long-term correction) in MT24/25 messages;Integration error in user receiver with regard to time after broadcast of MT58 with LTC (long-term correction) in MT24/25 messages; Range error is within 0.3m for 300 seconds integration.Range error is within 0.3m for 300 seconds integration.  Note that ephemeris message of SBAS has timeout interval of s. QZS-1 Reconstructed from broadcast Nav Msg on L1C/A PRN :00 to 24:00 GPST Processing by ENRI Assumed user Tokyo

ION ITM 30 Jan.-1 Feb ENRI S LIDE 16 User Receiver Setup JAVAD ALPHA-G3T with QZSS extension

ION ITM 30 Jan.-1 Feb ENRI S LIDE 17 HPE w/L1-SAIF Ranging :18:45 to 21:16:20 L1-SAIF (PRN183) Ranging ON L1SMS Configuration: 6 DF GPS GMS (GEONET) 6 DF GPS GMS (GEONET) 4 SF GPS/QZS GMS (JAXA) 4 SF GPS/QZS GMS (JAXA) User TokyoReceiver: JAVAD ALPHA-G3T JAVAD ALPHA-G3T Processing by ENRI Mask 5deg, Smoothing 100s Mask 5deg, Smoothing 100s L1-SAIF Correction L1-SAIF Ranging Hor RMS Hor Max Ver RMS Ver Max OFFOFF m m m m ON m m m m ONOFF m m m m ON m m m m

ION ITM 30 Jan.-1 Feb ENRI S LIDE 18 HPE w/o L1-SAIF Ranging L1-SAIF Correction L1-SAIF Ranging Hor RMS Hor Max Ver RMS Ver Max OFF OFF m m m m ON m m m m ON OFF m m m m ON m m m m :18:45 to 21:16:20 L1-SAIF (PRN183) Ranging OFF L1SMS Configuration: 6 DF GPS GMS (GEONET) 6 DF GPS GMS (GEONET) 4 SF GPS/QZS GMS (JAXA) 4 SF GPS/QZS GMS (JAXA) User TokyoReceiver: JAVAD ALPHA-G3T JAVAD ALPHA-G3T Processing by ENRI Mask 5deg, Smoothing 100s Mask 5deg, Smoothing 100s

ION ITM 30 Jan.-1 Feb ENRI S LIDE 19 Observed Residuals :18:45 to 21:16:20 L1-SAIF Correction ON L1SMS Configuration: 6 DF GPS GMS (GEONET) 6 DF GPS GMS (GEONET) 4 SF GPS/QZS GMS (JAXA) 4 SF GPS/QZS GMS (JAXA) User TokyoReceiver: JAVAD ALPHA-G3T JAVAD ALPHA-G3T Processing by ENRI Mask 5deg, Smoothing 100s Mask 5deg, Smoothing 100s Residual error dependents upon elevation angle for GPS satellites;Residual error dependents upon elevation angle for GPS satellites; L1-SAIF: Looks small dependency.L1-SAIF: Looks small dependency.

ION ITM 30 Jan.-1 Feb ENRI S LIDE 20 Observed Residuals :18:45 to 21:16:20 L1-SAIF Correction ON L1SMS Configuration: 6 DF GPS GMS (GEONET) 6 DF GPS GMS (GEONET) 4 SF GPS/QZS GMS (JAXA) 4 SF GPS/QZS GMS (JAXA) User TokyoReceiver: JAVAD ALPHA-G3T JAVAD ALPHA-G3T Processing by ENRI Mask 5deg, Smoothing 100s Mask 5deg, Smoothing 100s PRN 3 operates with Cs AFS; PRN 6 with Rb AFS;PRN 3 operates with Cs AFS; PRN 6 with Rb AFS; L1-SAIF is comparable to GPS signal; A bit noisy at high elevation.L1-SAIF is comparable to GPS signal; A bit noisy at high elevation.

ION ITM 30 Jan.-1 Feb ENRI S LIDE 21 Residuals on L1-SAIF Residual error within 1.8m from low to high elevation angle; 0.44m RMS;Residual error within 1.8m from low to high elevation angle; 0.44m RMS; Observed a small uncorrected bias.Observed a small uncorrected bias :18:45 to 21:16:20 L1-SAIF Correction ON L1SMS Configuration: 6 DF GPS GMS (GEONET) 6 DF GPS GMS (GEONET) 4 SF GPS/QZS GMS (JAXA) 4 SF GPS/QZS GMS (JAXA) User TokyoReceiver: JAVAD ALPHA-G3T JAVAD ALPHA-G3T Processing by ENRI Mask 5deg, Smoothing 100s Mask 5deg, Smoothing 100s

ION ITM 30 Jan.-1 Feb ENRI S LIDE 22 Residuals on GPS RMS of residual error: 0.4 to 0.5m for GPS satellites;RMS of residual error: 0.4 to 0.5m for GPS satellites; Largely biased.Largely biased. PRN 3 with Cs AFS PRN 6 with Rb AFS

ION ITM 30 Jan.-1 Feb ENRI S LIDE 23 Continuous Observation ENRI has been conducting continuous observation of L1-SAIF signal for technical verification since October 2011; Also observes other supplement signals;ENRI has been conducting continuous observation of L1-SAIF signal for technical verification since October 2011; Also observes other supplement signals; Observation is available on the web: URL is available on the web: URL Range measurements are converted into RINEX format and navigation message is formatted in EMS file; Both are slightly extended for QZSS;Range measurements are converted into RINEX format and navigation message is formatted in EMS file; Both are slightly extended for QZSS;  Identifier: ‘J01’ for L1C/A and ‘S83’ for L1-SAIF. Data files are stored on daily basis.Data files are stored on daily basis. ReceiverJAVAD ALPHA-G3T Antenna Location ENRI, Tokyo - Top of the tower of No. 6 Building N E m from ellipsoid X= Y= Z= AntennaTrimble Zephyr Geodetic 2 (L1/L2/L5) Target SVGPS, GLONASS, SBAS, QZSS (incl. L1-SAIF) MeasurementsCode Range, Carrier Range, Doppler, C/N 0 (L1, L2, L5) Note - Sometimes there is missing data due to some reason such as power outage.

ION ITM 30 Jan.-1 Feb ENRI S LIDE 24 QZSS L1-SAIF Data Source URL General Information, RINEX observation, EMS message archive, and schedule of L1-SAIF experiments by ENRIGeneral Information, RINEX observation, EMS message archive, and schedule of L1-SAIF experiments by ENRI QZSS L1-SAIF General Information List of RINEX Files

ION ITM 30 Jan.-1 Feb ENRI S LIDE 25Conclusion ENRI has been developing L1-SAIF signal:ENRI has been developing L1-SAIF signal: –Signal design: GPS/SBAS-like L1 C/A code (PRN 183); –Planned as an augmentation to mobile users. Ranging Function of L1-SAIF:Ranging Function of L1-SAIF: –Available as an additional ranging source with self-contained Ephemeris Information; –L1-SAIF Master Station (L1SMS) has been upgraded to broadcast Ephemeris Information and Corrections for L1-SAIF signal itself; –Tested successfully; Confirmed that residual error was comparable to GPS; –Ranging function reduces the maximum position error for both horizontal and vertical. Ongoing work:Ongoing work: –Experiments on mobile conditions; –Broadcasting corrections for MSAS and GLONASS satellites. L1-SAIF observation is available at observation is available at RINEXhttp:// EMShttp://