ESOC Combined GNSS Processing

1
ESOC Combined GNSS Processing

• T. Springer, F. Dilssner, E. Schoenemann,
• I. Romero, J. Tegedor, F. Pereira, J. Dow

2
Motivation

• IGS International GNSS Service gt not only GPS!
• Called GNSS Service since 2005!
• butIGS network is far from being a GNSS
  tracking network!
• GLONASS is going towards full constellation by
  2009
• End of 2008 possibly 22 satellites
• Galileo is coming!
• First two test satellites are flying (GIOVE-A and
  GIOVE-B)
• Global tacking network available (13 GESS)
• New and better signals!
• Compass developments!?
• Additional GPS satellite provide some benefits
• Additional other GNSS satellites with different
  orbit characteristics' may provide even more
  benefits (ERPs, Geocenter, yearly signals)
• but biases between different GNSS systems may
  obscure the potential benefits

3
Giove-A versus GPS Signal Quality
4
GESS (GIOVE) Tracking Network
5
IGS GNSS Tracking Network
Almost no US nor Canadian GNSS Stations!
6
Pseudo Graphics of GNSS Tracking

• G17
  
• G12
  
• G15
  
• G29
  
• G07
  
• ----------------------------------------
  ----------------------

R04 2345444444444449657888879
987789897796556465 R06
9764566667999986666557773444
5768889999 R08 9-98
89888887744344568-9545544456788858
R10 99887895553355677554555455
75689888998 R11
223344445577889--21122433333233333667
6332333- R13 554433343455559
---4332223343333233-55-689
R14 754555445546668
9888989999665565669 R15
777633333223322369888555
3343333333422124459 R17 565-
-2222323333-46777995------333333233333668
- R19 99998554666696666455667
9688988977999998 R20
78899999999422579765555445546668
98899 R23 56699887
988889976676765554445666
R24 5544788999878
965433556887555555558
----------------------------------------
----------------------
E01 -344444444433-222--3334455555555566553334443
3333334444456666566666667776 E16
3444555566555556666654444454432244444444455555444
56777555554344335555554 --------------------
----------------------------------------
-- Timestep per interval (sec) 1200
7
GPS Giove-A Combined Analysis

• Giove-A Microwave Analysis (150 days)
• IGS final orbits and clocks fixed
• Estimated parameters
• Giove-A orbit and clock
• GESS station coordinates and clocks
• Receiver dependent bias between GPS and Giove-A
• Daily solutions saving the normal equations
• Generate n-day solution based on normal equations
  (n 1, 2, 3, 4, and 5)
• Giove-A Combined Microwave and SLR Analysis
• Repeat analysis above but now including all SLR
  observations from the Giove-A satellite.
• Validation Analysis
• Repeat the analysis above but in addition treat
  one of the GPS satellites in the same way as the
  Giove-A satellite

8
Giove-A versus GPS Orbit Quality
IGS 2-day Orbit Overlap RMS 11 mm
Glonass 2-day Orbit Overlap RMS 173 mm
9
Giove-A Receiver Intersystem Bias
Orbit Quality surprisingly good given the poor
quality of the tracking network!
10
BAHN Intersystem Bias estimation R04
TRIMBLE
LEICA
JPS
TPS
11
Conclusions

• The IGS is currently mainly a GPS-only service!
• No reasonable GNSS tracking network
• No GNSS product with IGS label
• Buttwo ACs (CODE and ESOC) provide true combined
  GNSS solutions
• Several formats do (still) not cater for GLONASS
  let alone GALILEO, especially in the real time
  area!
• To become a true GNSS service IGS will have to
• Enforce that all (new) IGS stations are GNSS
  stations
• Start generating a true GNSS combined product
  (orbit and clock)
• Ensure that all formats are GNSS capable
• Should start ASAP!
• Significant interest and demand exists for GNSS
  products!

To GPS or to GNSS that is the question!
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Thank You!