1、T. Sakai, H. Yamada, and K. Ito Electronic Navigation Research Institute, Japan,Ranging Quality of QZSS L1-SAIF Signal,ION ITM 2012 Newport Beach, CA Jan.30 - Feb.1, 2012,ION ITM 30 Jan.-1 Feb. 2012 - ENRI,SLIDE 1,Introduction,QZSS (Quasi-Zenith Satellite System) program: Regional navigation service
2、 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, 20
3、10.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
4、-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 compa
5、rable to GPS thanks to signal bandwidth of 24 MHz.,ION ITM 30 Jan.-1 Feb. 2012 - ENRI,SLIDE 2,QZSS Concept,Broadcast signal from high elevation angle; Applicable to navigation services for mountain area and urban canyon; Augmentation signal from the zenith could help users to acquire other GPS satel
6、lites at any time.,Footprint of QZSS orbit; Centered at 135E; Eccentricity 0.075, Inclination 43deg.,ION ITM 30 Jan.-1 Feb. 2012 - ENRI,SLIDE 3,Inclined Geosynchronous Orbit,Ground Track,Semi-major axis (42164km) is equal to GEO orbit: synchronous with rotation of the earth; Inclined obit makes grou
7、nd 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.,Perigee 32000km,Apogee 40000km,ION ITM 30 Jan.-1 Feb. 2012 - ENRI,SLIDE 4,Space Segment: QZS-1,ION ITM 30 Ja
8、n.-1 Feb. 2012 - ENRI,SLIDE 5,QZSS Frequency Plan,Find detail in IS-QZSS document.,ION ITM 30 Jan.-1 Feb. 2012 - ENRI,SLIDE 6,QZSS broadcasts wide-area augmentation signal: Called L1-SAIF (Submeter-class Augmentation with Integrity Function); Designed and developed by ENRI.L1-SAIF signal offers: Wid
9、e-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: Broadcast on L1 freq. with RHCP
10、; 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 I
11、TM 30 Jan.-1 Feb. 2012 - ENRI,SLIDE 7,L1-SAIF Signal,User GPS Receivers,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; Message-oriented information tra
12、nsmission: flexible contents.,SAIF： Submeter-class Augmentation with Integrity Function,ION ITM 30 Jan.-1 Feb. 2012 - ENRI,SLIDE 8,L1-SAIF Corrections,Example of user position error at Site 940058 (Takayama: near center of monitor station network); Realtime operation with MSAS-like 6 monitor station
13、s; Period: 19-23 Jan. 2008 (5 days); L1-SAIF provides corrections only;No L1-SAIF ranging.,Note: Results shown here were obtained with survey-grade antenna and receiver in open sky condition.,No L1-SAIF Ranging,ION ITM 30 Jan.-1 Feb. 2012 - ENRI,SLIDE 9,Usage of L1-SAIF Ranging,Ranging function of L
14、1-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 Sta
15、tion (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: RF quality: Expect comparable to GPS thanks to sign
16、al 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. 2012 - ENRI,SLIDE 10,L1-SAIF Mes
17、sage Structure,ION ITM 30 Jan.-1 Feb. 2012 - ENRI,SLIDE 11,L1-SAIF Message (1),ION ITM 30 Jan.-1 Feb. 2012 - ENRI,SLIDE 12,L1-SAIF Message (2),ION ITM 30 Jan.-1 Feb. 2012 - ENRI,SLIDE 13,L1-SAIF Ephemeris (MT58),ION ITM 30 Jan.-1 Feb. 2012 - ENRI,SLIDE 14,Generation of Ephemeris,Ephemeris informatio
18、n 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).,ION ITM 30 Jan.-1 Feb. 2012 - ENRI,SLIDE 15,SV Position E
19、rror of MT58,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. Note that ephemeris message of SBAS has timeout interval of 240-360s.,QZS-1 Reconstructed from broa
20、dcast Nav Msg on L1C/A PRN 1932011-08-18 00:00 to 24:00 GPSTProcessing by ENRIAssumed user location:ENRI, Tokyo,ION ITM 30 Jan.-1 Feb. 2012 - ENRI,SLIDE 16,User Receiver Setup,JAVAD ALPHA-G3T with QZSS extension,ION ITM 30 Jan.-1 Feb. 2012 - ENRI,SLIDE 17,HPE w/L1-SAIF Ranging,2011-08-18 02:18:45 to
21、 21:16:20L1-SAIF (PRN183) Ranging ONL1SMS Configuration:6 DF GPS GMS (GEONET)4 SF GPS/QZS GMS (JAXA)User location:ENRI, TokyoReceiver:JAVAD ALPHA-G3TProcessing by ENRIMask 5deg, Smoothing 100s,ION ITM 30 Jan.-1 Feb. 2012 - ENRI,SLIDE 18,HPE w/o L1-SAIF Ranging,2011-08-18 02:18:45 to 21:16:20L1-SAIF
22、(PRN183) Ranging OFFL1SMS Configuration:6 DF GPS GMS (GEONET)4 SF GPS/QZS GMS (JAXA)User location:ENRI, TokyoReceiver:JAVAD ALPHA-G3TProcessing by ENRIMask 5deg, Smoothing 100s,ION ITM 30 Jan.-1 Feb. 2012 - ENRI,SLIDE 19,Observed Residuals,2011-08-18 02:18:45 to 21:16:20L1-SAIF Correction ONL1SMS Co
23、nfiguration:6 DF GPS GMS (GEONET)4 SF GPS/QZS GMS (JAXA)User location:ENRI, TokyoReceiver:JAVAD ALPHA-G3TProcessing by ENRIMask 5deg, Smoothing 100s,Residual error dependents upon elevation angle for GPS satellites; L1-SAIF: Looks small dependency.,ION ITM 30 Jan.-1 Feb. 2012 - ENRI,SLIDE 20,Observe
24、d Residuals,2011-08-18 02:18:45 to 21:16:20L1-SAIF Correction ONL1SMS Configuration:6 DF GPS GMS (GEONET)4 SF GPS/QZS GMS (JAXA)User location:ENRI, TokyoReceiver:JAVAD ALPHA-G3TProcessing by ENRIMask 5deg, Smoothing 100s,PRN 3 operates with Cs AFS; PRN 6 with Rb AFS; L1-SAIF is comparable to GPS sig
25、nal; A bit noisy at high elevation.,ION ITM 30 Jan.-1 Feb. 2012 - ENRI,SLIDE 21,Residuals on L1-SAIF,Residual error within 1.8m from low to high elevation angle; 0.44m RMS; Observed a small uncorrected bias.,2011-08-18 02:18:45 to 21:16:20L1-SAIF Correction ONL1SMS Configuration:6 DF GPS GMS (GEONET
26、)4 SF GPS/QZS GMS (JAXA)User location:ENRI, TokyoReceiver:JAVAD ALPHA-G3TProcessing by ENRIMask 5deg, Smoothing 100s,ION ITM 30 Jan.-1 Feb. 2012 - ENRI,SLIDE 22,Residuals on GPS,RMS of residual error: 0.4 to 0.5m for GPS satellites; Largely biased.,PRN 3 with Cs AFS,PRN 6 with Rb AFS,ION ITM 30 Jan.
27、-1 Feb. 2012 - ENRI,SLIDE 23,Continuous Observation,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 http:/www.enri.go.jp/sat/qzss_e.htm Range measurements
28、 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.,Note - Sometimes there is missing data due to some reason such as power outage.,ION ITM 30 Jan.-
29、1 Feb. 2012 - ENRI,SLIDE 24,QZSS L1-SAIF Data Source,URL http:/www.enri.go.jp/sat/qzss_e.htm General Information, RINEX observation, EMS message archive, and schedule of L1-SAIF experiments by ENRI,QZSS L1-SAIF General Information http:/www.enri.go.jp/sat/qzss_e.htm,List of RINEX Files http:/www.enr
30、i.go.jp/cnspub/sat/data/rinex/,ION ITM 30 Jan.-1 Feb. 2012 - ENRI,SLIDE 25,Conclusion,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: Available as an additional ranging source with se
31、lf-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: Experiments on mobile conditions; Broadcasting corrections for MSAS and GLONASS satellites.L1-SAIF observation is available at http:/www.enri.go.jp/sat/qzss_e.htmRINEX http:/www.enri.go.jp/cnspub/sat/data/rinex/EMS http:/www.enri.go.jp/cnspub/sat/data/ems/,
