Transcript Recent Development of QZSS L1

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
ION ITM 25-27 Jan. 2010 - ENRI
Introduction
SLIDE 1
• 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.
ION ITM 25-27 Jan. 2010 - ENRI
SLIDE 2
Part 1
Overview of QZSS Program
ION ITM 25-27 Jan. 2010 - ENRI
SLIDE 3
QZSS Concept
GPS/GEO
• Footprint of QZS orbit
• Centered 137E
• Eccentricity 0.1, Inclination 45deg
QZS
• Signal from high elevation angle
• Applicable to navigation services for
mountain area and urban canyon
ION ITM 25-27 Jan. 2010 - ENRI
QZSS Program
SLIDE 4
• 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 synchronization 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.
ION ITM 25-27 Jan. 2010 - ENRI
SLIDE 5
Overall Architecture
Navigation Signals
L1: 1575.42 MHz
L2: 1227.60 MHz
L5: 1176.45 MHz
LEX: 1278.75 MHz
QZS Satellite
GPS
Satellites
TWSTFT
Up:
4.43453GHz
Down: 12.30669GHz
Satellite
Laser Ranging
TT&C / NAV
Message Uplink
SLR Site
Monitor Station NW
Time Mgmt
Station
TT&C / NAV Msg
Uplink Station
User Receiver
Master Control
Station (MCS)
GEONET
(GSI)
Function distributed in each institute
Timing management by NICT,
WADGPS service by ENRI, etc.
TWSTFT: Two Way Satellite Time and Frequency Transfer
(Courtesy: JAXA QZSS PT)
ION ITM 25-27 Jan. 2010 - ENRI
SLIDE 6
Space Segment: QZS-1
Mass
Approx. 1,800kg (dry)
(NAV Payload：Approx. 320kg)
Power
Approx. 5.3 kW (EOL)
(NAV Payload: Approx. 1.9kW)
Design Life
10 years
Radiation Cooled TWT
TWSTFT Antenna
C-band TTC Antenna
Laser Reflector
L1-SAIF Antenna
L-band Helical Array
Antenna
ION ITM 25-27 Jan. 2010 - ENRI
QZSS Signals
SLIDE 7
• 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.
ION ITM 25-27 Jan. 2010 - ENRI
QZSS Frequency Plan
Signal
Channel
Frequency
SLIDE 8
Bandwidth
Min. Rx Power
L1CD
24 MHz
–163.0 dBW
L1CP
24 MHz
– 158.25 dBW
QZS-L1-C/A
24 MHz
– 158.5 dBW
QZS-L1-SAIF
24 MHz
– 161.0 dBW
24 MHz
– 160.0 dBW
25 MHz
– 157.9 dBW
25 MHz
– 157.9 dBW
42 MHz
– 155.7 dBW
QZS-L1C
1575.42 MHz
QZS-L2C
1227.6 MHz
L5I
QZS-L5
1176.45 MHz
L5Q
QZS-LEX
1278.75 MHz
Find detail in IS-QZSS document.
ION ITM 25-27 Jan. 2010 - ENRI
SLIDE 9
Part 2
L1-SAIF Signal Design
ION ITM 25-27 Jan. 2010 - ENRI
QZSS L1-SAIF Signal
SLIDE 10
• 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.
ION ITM 25-27 Jan. 2010 - ENRI
SLIDE 11
WADGPS Concept
Clock Correction
Ionospheric Correction
• Function of user location;
• Up to 100 meters;
• Vertical structure may be
described as a thin shell.
Ionosphere
• Same contribution to any user
location;
• Not a function of location;
• Needs fast correction.
Orbit Correction
• Different contribution to different
user location;
• Not a function of user location; but
a function of line-of-sight direction;
• Long-term correction.
Tropospheric Correction
Troposphere
• Function of user location, especially height of user;
• Up to 20 meters;
• Can be corrected enough by a fixed model.
ION ITM 25-27 Jan. 2010 - ENRI
SLIDE 12
SBAS/L1-SAIF Message Structure
Preamble
8 bits
Message Type
6 bits
Data Field
212 bits
250 bits per second
Transmitted First
MT
CRC parity
24 bits
Contents
Interval
[s]
MT
Contents
Interval
[s]
0
Test mode
6
17
GEO almanac
300
1
PRN mask
120
18
IGP mask
300
Fast correction & UDRE
60
24
FC & LTC
6
6
UDRE
6
25
Long-term correction
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
2～5
120
—
ION ITM 25-27 Jan. 2010 - ENRI
SBAS/L1-SAIF Message (1)
Message Type
Contents
SLIDE 13
Compatibility
Status
0
Test mode
Both
Fixed
1
PRN mask
Both
Fixed
Fast correction & UDRE
Both
Fixed
6
UDRE
Both
Fixed
7
Degradation factor for FC
Both
Fixed
8
Reserved
SBAS
Fixed
9
GEO ephemeris
SBAS
Fixed
10
Degradation parameter
Both
Fixed
12
SBAS network time
SBAS
Fixed
17
GEO almanac
SBAS
Fixed
18
IGP mask
Both
Fixed
24
Mixed fast/long-term correction
Both
Fixed
25
Long-term correction
Both
Fixed
26
Ionospheric delay & GIVE
Both
Fixed
2 to 5
ION ITM 25-27 Jan. 2010 - ENRI
SBAS/L1-SAIF Message (2)
Message Type
Contents
27
SBAS service message
28
Clock-ephemeris covariance
SLIDE 14
Compatibility
Status
SBAS
Fixed
Both
Fixed
29 to 51
(Undefined)
—
—
52
TGP mask
L1-SAIF
Tentative
5３
Tropospheric delay
L1-SAIF
Tentative
(Advanced Ionospheric delay)
L1-SAIF
TBD
56
Intersignal biases
L1-SAIF
Tentative
57
(Ephemeris-related parameter)
L1-SAIF
TBD
58
QZS ephemeris
L1-SAIF
Tentative
59
(QZS almanac)
L1-SAIF
TBD
60
(Regional information)
L1-SAIF
TBD
61
Reserved
L1-SAIF
Tentative
62
Reserved
Both
Fixed
63
Null message
Both
Fixed
54 to 55
ION ITM 25-27 Jan. 2010 - ENRI
SLIDE 15
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
GPS/L1-SAIF
Receiver
ION ITM 25-27 Jan. 2010 - ENRI
GPS/L1-SAIF Receiver
SLIDE 16
• 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
ION ITM 25-27 Jan. 2010 - ENRI
SLIDE 17
RF Compatibility Test
ENRI (Chofu, Tokyo)
Spirent
Scenario
File
GPS/L1-SAIF
Simulator
L1-SAIF Signal
RF Cable
Furuno Electric
GPS/L1-SAIF
Receiver
TCP/IP
L1-SAIF Message
Decoded Message
Compare
• 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 2second before the applicable time of transmission;
• Successfully completed in Feb. 2009.
ION ITM 25-27 Jan. 2010 - ENRI
SLIDE 18
RF Compatibility Test
2008/9/10 00:05:00 to 06:00:00 (6 hours)
Standalone GPS
L1-SAIF Augmentation
OK!
ION ITM 25-27 Jan. 2010 - ENRI
SLIDE 19
Part 3
L1-SAIF Master Station (L1SMS)
ION ITM 25-27 Jan. 2010 - ENRI
SLIDE 20
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.
QZS
GPS
Closed
Loop
Measured
Data
L1-SAIF
Message
GEONET
L1SMS
QZSS MCS
GSI
ENRI
JAXA
ION ITM 25-27 Jan. 2010 - ENRI
SLIDE 21
L1SMS Installed at ENRI
I/F
Message
Generator
Ionosphere
Processor
Storage
Storage
Router to
GEONET
GEONET
Server
Storage
UPS
UPS
ION ITM 25-27 Jan. 2010 - ENRI
SLIDE 22
Configuration of L1SMS
GEONET
TCP/IP
Observation
File (RINEX)
via FTP
Batch Processor
(IFB Estimation)
Dual Freq. ANT
GEONET Server
Primary Receiver
Message
Output
via TCP/IP
Interface Processor
IFB
Estimates
L1SMS Batch Subsystem
Message Generator
(L1SMG)
Ionosphere Processor
Troposphere Processor
L1SMS Realtime Subsystems
ION ITM 25-27 Jan. 2010 - ENRI
JAXA-ENRI Interface (G-ICD)
SLIDE 23
• 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.
ENRI
Router
L1SMS
Router
Upload Message
ISDN
Optical
Other Data
JAXA
Router
MCS A
Router
MCS B
ION ITM 25-27 Jan. 2010 - ENRI
JAXA-ENRI Interface (G-ICD)
SLIDE 24
Packet ID
Contents
Direction
Link
Interval
0xC0
Upload Message
L1SMS -> MCS
ISDN
1s
0xC1
Upload Message Echo
L1SMS <- MCS
ISDN
1s
0x02
SMS Status
L1SMS -> MCS
Optical
5s
0xE2
GPS/QZS Observation
L1SMS <- MCS
Optical
1s
0xE4
GPS Observation
L1SMS <- MCS
Optical
1s
0xE1
Monitor Station Status
L1SMS <- MCS
Optical
5s
0x11
Telemetry Command
L1SMS <-> MCS
Optical
N/A
0x12
Telemetry Data
L1SMS <- MCS
Optical
min 1 s
0x01
Experiment Status
L1SMS <- MCS
Optical
10 s
0x21
Orbit and Clock
L1SMS <- MCS
Optical
30 s
ION ITM 25-27 Jan. 2010 - ENRI
SLIDE 25
Closed-Loop Interface Test
NEC (Fuchu, Tokyo)
ENRI
L1SMS
Simulator
HUB
Upload Message
LAN
Log
GPS/L1-SAIF
Receiver
JAXA
HUB
L1-SAIF Signal
RF Cable
MCS B
Navigation
Payload EM
Log
Log
Nav payload
• 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.
Receiver
L1SMS Sim
ION ITM 25-27 Jan. 2010 - ENRI
SLIDE 26
JAXA-ENRI Interface Test
ENRI (Chofu, Tokyo)
ENRI
Router
L1SMS
Simulator
Router
JAXA (Tsukuba)
Upload Message
ISDN
Optical
Other Data
Log
JAXA
Router
MCS A
Router
MCS B
Log
• 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.
ION ITM 25-27 Jan. 2010 - ENRI
SLIDE 27
Part 4
Realtime Operation Test
ION ITM 25-27 Jan. 2010 - ENRI
Realtime Operation Test
SLIDE 28
GMS Stations (6) for L1SMG
IMS Station (200) for ICP
Evaluation Locations (14)
L1-SAIF Experimental Area
• 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.
ION ITM 25-27 Jan. 2010 - ENRI
SLIDE 29
Results – Position Error Sample
L1-SAIF Augmentation
MSAS Augmentation
Standalone GPS
• 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).
Horizontal
Error
Vertical
Error
RMS
0.23 m
0.36 m
MAX
1.67 m
3.35 m
RMS
0.46 m
0.59 m
MAX
1.73 m
2.43 m
Standalone RMS
GPS
MAX
1.25 m
2.99 m
4.30 m
8.11 m
System
L1-SAIF
MSAS
ION ITM 25-27 Jan. 2010 - ENRI
SLIDE 30
Location vs. Horizontal Accuracy
• ICP improves position accuracy in the Southern Region;
• First order estimation is better to ensure 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.
SLIDE 31
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
SLIDE 32
ION ITM 25-27 Jan. 2010 - ENRI
SLIDE 33
Uplink from Tokyo
ETS-VIII Satellite
Ethernet
L1-SAIF message
L1-SAIF Master Station
RF signal
ETS-VIII Terminal Equipment
SATCOM Antenna
ION ITM 25-27 Jan. 2010 - ENRI
SLIDE 34
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
ION ITM 25-27 Jan. 2010 - ENRI
L1-SAIF Receiver Output
SLIDE 35
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
ION ITM 25-27 Jan. 2010 - ENRI
SLIDE 36
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]
940030
Oga
93101
Omaezaki
940058
Takayama
940085
Tosashimizu
950491
Sata
Hor
0.362
0.363
0.362
0.423
0.502
Ver
0.517
0.536
0.548
0.608
0.739
Hor
0.460
0.440
0.347
0.416
0.552
Ver
0.657
1.236
0.678
0.699
1.371
Site
Period I
Period II
ION ITM 25-27 Jan. 2010 - ENRI
Conclusion
SLIDE 37
• 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.