compass/beidou: system status and initial service -...
TRANSCRIPT
Compass/Beidou: system status and initial
service
Junping Chen, Bin Wu, Xiaogong Hu
Shanshi Zhou, Yueling Cao, Xiaoli Wu, Nan Xing
Shanghai Astronomical Observatory (SHAO)
IGS Workshop on GNSS Biases
18 to 19 January 2012,
University of Bern, Switzerland
Content
�Compass/Beidou: system design
�Tgd (Time group delay)
�Ionosphere model
22
�User positioning
Compass: history and innovations
Beidou-1 (2000- )
�2 GEO satellites, active positioning system
Beidou-2 (2007- )
�Release of test ICD, 27 Dec. 2011
�Announcement of initial service: 4 GEO satellites, 5 IGSO by
end of 2011; Announced positioning ~25m; timing ~50ns
�Regional service over 5 GEO, 5 IGSO, 4 MEO by end of 2012?
�Global service: 5 GEO, 30 None-GEO, by 2020
Distinguished Features�Mixed constellation: GEO+IGSO+MEO
�Two-way time transfer technique: time synchronization
between ground stations and satellites
�Short message capability
�Inter-satellite link design
�AA
�Global service: 5 GEO, 30 None-GEO, by 2020
3
3GEO+4IGSO:
Constellation and daily PDOP
4
Next step:
5+5+4
Residual (RMS) of GEO/IGSO orbit determination of 3 days: �Phase better than 1cm
�Range better than 1m
GEO/IGSO orbits and clocks
5
Satellite Clock differences between
� the solution using Pseudorange+phase obs and,
�Two-way time synchronization
SLR Ranging residuals shows similar values
�Orbit/clock correlation of GEO/IGSO satellites!!!
GEO/IGSO orbits and clocks -cont.
6
Compass: Tgd
Tgd (Timing group delay) of 300 days
7
GPS: rms ~0.2ns; global network
Compass: rms 0.4-0.6ns, regional network
Tgd estimation will be improved with more stations
Variation of Tgd could be well modelled!!
Compass: Broadcast ionosphere modelSingle frequency positioning using GPS & Compass Ion model
Site3D RMS (m)
ratioDual-frequency GPS K8 Compass Para8
ALBH 3.07 5.55 5.07 16.6%
CHAN 2.64 4.35 3.50 35.3%
LHAZ 4.51 6.71 5.75 26.6%
MIZU 2.83 4.28 3.77 22.4%
PERT 6.02 6.03 6.31 -9.5%
8
Compass Ion model is generally better than GPS model!
Not the case for station in southern hemisphere, as the current compass
mode was derived using the regional monitor stations in China
PTBB 6.18 5.42 5.20 8.0%
TIDB 2.53 3.99 4.61 -33.5%
TWTF 3.74 5.08 4.57 19.1%
USUD 4.08 6.02 5.78 7.8%
2 2
8 8
2
8
100%GPSK Compass
GPSK
Rms RmsRatio
Rms
−
= ⋅
Navigation with Compass: Dual frequency
Site: Compass monitor station, 48 hr data
9
RMS (m) North East Up 3D
Open service 3.86 1.04 5.25 6.60
Authorized user 0.82 0.31 1.37 1.63
Navigation with Compass: Single frequency
Site: Compass monitor station, 48 hr data;
10
RMS (m) North East Up 3D
Open service 3.85 1.31 5.51 6.84
Authorized user 1.81 0.48 3.55 4.02
User Positioning with Compass: Static PPP
Site: Compass monitor stations, daily coordinates variation
North East Up 3D
Repeatability(cm) 2.05 1.23 4.41 5.07
11
Conclusion
�Compass on the road for global positioning system
�Compass(current constellation and regional tracking
network) Tgd: 2~30 ns, with variation modeled and
predicted better than 1.0 ns.
�Compass Ionosphere model shows better performance �Compass Ionosphere model shows better performance
than GPS model for single frequency receivers.
�Better than 10 m navigation accuracy for dual-
frequency civil users; 2 m for authorized users.
�Better than 5 cm in post-processing positioning using
daily phase data.
12
Shanghai Astronomical
Observatory (SHAO)
Top:Observatory
(SLR+VLBI+
GNSS+Telescope)
Right: the Institute
ThankThank youyou!!