Transcript Quasi-Zenith Satellite System L1

Munich SatNav Summit
Munich, Germany
March 25-27, 2014
Quasi-Zenith Satellite System
L1-SAIF Augmentation Signal
Takeyasu Sakai
Electronic Navigation Research Institute, Japan
Munich SatNav Summit 2014 - ENRI
Introduction
SLIDE 1
• QZSS (Quasi-Zenith Satellite System) program:
– Regional navigation service broadcast from high-elevation angle by three or
more satellites on the inclined geosynchronous (quasi-zenith) orbit and GEO;
– Broadcast GPS-like supplemental signals on three frequencies and two
augmentation signals, L1-SAIF and LEX;
– The first QZS satellite successfully launched on Sept. 11, 2010.
• 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 developed L1-SAIF signal and experimental facility:
– Signal design: SBAS-like signal and message on L1 frequency;
– Implemented L1-SAIF Master Station (L1SMS) which generates augmentation
message stream in realtime and transmits it to the QZSS MCS;
– Conducted experiments of L1-SAIF successfully.
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SLIDE 2
QZSS Concept
GPS/GEO
• Footprint of QZSS orbit;
• Centered at 135E;
• Eccentricity 0.075, Inclination 43deg.
QZS
• 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 satellites at
any time.
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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 Life
SLIDE 3
10 years
Radiation Cooled TWT
TWSTFT Antenna
Successfully launched on Sept.
11, 2010 and settled on QuasiZenith Orbit (IGSO).
C-band TTC Antenna
Nickname: “Michibiki”
Laser Reflector
L1-SAIF Antenna
L-band Helical Array
Antenna
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Broadcast Ranging Signals
Supplemental
Signals
QZS satellites
SLIDE 4
Supplemental Signals by JAXA
• GPS-like L1C/A, L2C, L5, and L1C signals (PRN
193) working with GPS;
• Improves availability of navigation;
• Minimum modifications from GPS signals.
L1-SAIF by ENRI
• SBAS-like C/A code (PRN 183) signal on L1 freq.;
Reasonable performance for mobile users;
• Augmentation to GPS; Potentially plus GLONASS
and Galileo.
Augmentation
Signals
LEX by JAXA
• For carrier-based experimental purposes;
• Original CPSK signal on E6 frequency;
• Member organizations may use LEX as 2kbps
experimental data channel.
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SLIDE 5
L1-SAIF Signal
L1-SAIF Signal
QZS satellites
Ranging
Function
GPS Constellation
Error
Correction
Integrity
Function
• SBAS-like augmentation signal; Differences are
PRN code (183 for L1-SAIF) and Doppler only;
• 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;
• See IS-QZSS for detail (Available at JAXA HP).
SAIF： Submeter-class Augmentation with Integrity Function
Ranging Signal
User GPS
Receivers
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ENRI L1-SAIF Master Station
SLIDE 6
• 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;
– Dual frequency GPS measurements at some locations in Japan necessary to
generate L1-SAIF messages are sent from GEONET in realtime.
GNSS
Satellites
GEONET
QZS
Measurements
L1SMS
L1-SAIF
Message
QZSS MCS
GSI Server
ENRI
JAXA TKSC
(Tokyo)
(Tokyo)
(Tsukuba)
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SLIDE 7
L1-SAIF Performance
GPS Only Result
6 reference
stations
User location
for this test
L1-SAIF experimental area
Standalone GPS
L1-SAIF Augmentation
Horizontal
Error
1.45 m
Standalone RMS
GPS
Max
6.02 m
RMS
0.29 m
w/ L1-SAIF
Max
1.56 m
System
• Example of user position error at Site
940058 (Takayama);
• Realtime operation with MSAS-like 6
reference stations in Japan;
• Period: 19-23 Jan. 2008 (5 days).
Vertical
Error
2.92 m
8.45 m
0.39 m
2.57 m
Note: Results shown here were obtained with geodeticgrade antenna and receivers at open sky condition.
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Experiment by Car
SLIDE 8
• L1-SAIF experiment:
GPS+IMU
– L1-SAIF is originally planned as an
augmentation to mobile users with a certain
velocity;
– Experiment with a car;
– Location: urban/suburban environment,
freeway;
– Experiment period: Dec. 2010 to March 2011.
• Experiment setup:
– Reference: GPS+IMU sensor;
– Post-processing with GEONET stations (2030 km separation) for accurate reference;
– GPS/L1-SAIF receiver and PC in cabin;
– Receives L1-SAIF signal on PRN 183;
– Applies L1-SAIF corrections in realtime and
outputs position fix.
GPS/L1-SAIF Rx
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SLIDE 9
On the Freeway
GEONET
Ichinomiya
GEONET
Nakamichi
Plan View of the Route
2 km
Typical Situation
• On Dec. 14, 2010; QZS near the Zenith;
• About 10 km drive at the Kofu Basin on Chuo Freeway going
westward from Tokyo;
• Plain ground with less bridges across the Freeway.
Position Error, m
Horizontal 水平測位誤差（m）
0
15min
時刻（UTC）
UTC Time 1:22:08 to 1:37:08
1:36:08 AM
1:35:08 AM
1:34:08 AM
1:33:08 AM
1:32:08 AM
1:31:08 AM
1:30:08 AM
1:29:08 AM
1:28:08 AM
1:27:08 AM
1:26:08 AM
1:25:08 AM
1:24:08 AM
1:23:08 AM
1:22:08 AM
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Freeway: GPS No Augmentation
SLIDE 10
Chuo Freeway:
GPS without Augmentation
GPS測位精度（中央道）
5
4
3
2
1
1.2m
Position Error, m
Horizontal水平測位誤差（m）
0
15min
時刻（UTC）
UTC Time 1:22:08 to 1:37:08
1:36:08 AM
1:35:08 AM
1:34:08 AM
1:33:08 AM
1:32:08 AM
1:31:08 AM
1:30:08 AM
1:29:08 AM
1:28:08 AM
1:27:08 AM
1:26:08 AM
1:25:08 AM
1:24:08 AM
1:23:08 AM
1:22:08 AM
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Freeway: L1-SAIF Augmented
SLIDE 11
Chuo Freeway:
L1-SAIF Augmentation
L1-SAIF測位精度（中央道）
5
4
3
2
1
0.5m
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SLIDE 12
In Tsukuba City
GEONET
Tsukuba 1
1 km
Plan View of the Route
Typical Situation
• On Dec. 16, 2010; QZS near the Zenith;
• About 6 km drive in West part of Tsukuba City in Ibaraki Pref.;
• Road on the ground level with less tall buildings around.
Error, m
Position
Horizontal水平測位誤差
（ｍ）
0
15min
時刻（UTC）
UTC Time 5:30:01
to 5:45:01
5:44:01 AM
5:43:01 AM
5:42:01 AM
5:41:01 AM
5:40:01 AM
5:39:01 AM
5:38:01 AM
5:37:01 AM
5:36:01 AM
5:35:01 AM
5:34:01 AM
5:33:01 AM
5:32:01 AM
5:31:01 AM
5:30:01 AM
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Tsukuba: GPS No Augmentation
SLIDE 13
Tsukuba: GPS
without Augmentation
GPS測位精度（つくば2）
5
4
3
2
2.0m
1
Error, m
Position
Horizontal水平測位誤差
（ｍ）
0
15min
時刻（UTC）
UTC Time 5:30:01
to 5:45:01
5:44:01 AM
5:43:01 AM
5:42:01 AM
5:41:01 AM
5:40:01 AM
5:39:01 AM
5:38:01 AM
5:37:01 AM
5:36:01 AM
5:35:01 AM
5:34:01 AM
5:33:01 AM
5:32:01 AM
5:31:01 AM
5:30:01 AM
Munich SatNav Summit 2014 - ENRI
Tsukuba: L1-SAIF Augmented
SLIDE 14
Tsukuba:
L1-SAIF Augmentation
L1-SAIF測位精度（つくば2）
5
4
3
2
1
0.6m
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Conclusion
SLIDE 15
• ENRI has developed QZSS L1-SAIF signal:
– Signal design: SBAS-like C/A code signal (PRN 183) on L1 frequency;
– Planned as an augmentation to mobile users;
– Implemented L1-SAIF Master Station (L1SMS) which generates augmentation
message stream in realtime and transmit it to QZSS MCS.
• QZSS satellite “Michibiki”:
– The first satellite for QZSS, “Michibiki”, was successfully launched in 2010;
– Continuously broadcasting navigation signals just as planned.
• L1-SAIF Experiments:
– ENRI has conducted L1-SAIF experiments successfully and confirmed submeterclass accuracy as originally planned;
– Currently investigations are in progress on usage of Multi-GNSS with GLONASS,
dual frequency augmentation, and application in short message service;
– Information is available at: http://www.enri.go.jp/sat/qzss_e.htm