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Simulations for VLBI 2010

INSTITUTE OF GEODESY AND GEOPHYSICS. Simulations for VLBI 2010. Jörg Wresnik, Johannes Böhm, Harald Schuh. Institute of Geodesy and Geophysics (IGG), TU Vienna, Austria. 4 th IVS General Meeting Concepción, Enero, 2006. Simulations for VLBI 2010 IGG-Vienna.

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Simulations for VLBI 2010

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  1. INSTITUTE OF GEODESY AND GEOPHYSICS Simulations forVLBI 2010 Jörg Wresnik, Johannes Böhm, Harald Schuh Institute of Geodesy and Geophysics (IGG), TU Vienna, Austria 4th IVS General Meeting Concepción, Enero, 2006

  2. Simulations forVLBI 2010 IGG-Vienna INSTITUTE OF GEODESY AND GEOPHYSICS • observing strategies and scheduling • - 16 station networks • - 32 station networks • antenna configuration • - identical antennas at all sites • - many small antennas vs. few large antennas • network geometry • - where to build new stations • troposphere and clock modeling • - low elevations vs. mapping function errors • - implication of multiple antennas at one station

  3. The software packages INSTITUTE OF GEODESY AND GEOPHYSICS scheduling the observations least-squares adjustment interpretation of the results

  4. Creating a Schedule INSTITUTE OF GEODESY AND GEOPHYSICS Station select

  5. Creating a Schedule INSTITUTE OF GEODESY AND GEOPHYSICS Sources select

  6. OCCAM: least-squares adjustment INSTITUTE OF GEODESY AND GEOPHYSICS Gauss-Markov model v… vector of the residuals to the observations A… design matrix x… vector of unknowns l… difference between observed and computed values (o-c) P… weight matrix Qxx… cofactor matrix 02 Qxx… covariance matrix kij… correlations

  7. 1.) o – c: set to zero INSTITUTE OF GEODESY AND GEOPHYSICS l = o-c = 0 P = realistic standard deviations 02 = set to unity already done in OCCAM & first results in VV-SIM

  8. 2.) o – c: synthetic observations INSTITUTE OF GEODESY AND GEOPHYSICS l = o-c = random errors & systematic errors P = standard deviations corresponding to standard deviations of the observations which can be scaled with decreasing elevation e.g., extreme weather conditions can be taken from numerical weather models to create realistic l-vectors.

  9. Modeling extreme weather conditions INSTITUTE OF GEODESY AND GEOPHYSICS determine o-c by using ray tracing models

  10. Correlation matrix INSTITUTE OF GEODESY AND GEOPHYSICS standard parameters x coordinate y coordinate z coordinate clock offset clock rate clock rate squared zenith delay offset

  11. Correlation matrix INSTITUTE OF GEODESY AND GEOPHYSICS Earth orientation parameters x pole y pole dut1

  12. Correlation matrix INSTITUTE OF GEODESY AND GEOPHYSICS auxiliary parameters zenith delay rate

  13. Correlation matrix INSTITUTE OF GEODESY AND GEOPHYSICS auxiliary parameters clock rate gradient offset gradient rate

  14. Different network configurations INSTITUTE OF GEODESY AND GEOPHYSICS

  15. Different network configurations INSTITUTE OF GEODESY AND GEOPHYSICS Cofactors of xp, yp, dut1 xp = 33.4 µas yp = 17.3 µas dut1 = 0.7 µs 0.0544 0.0238 0.0689

  16. Different network configurations INSTITUTE OF GEODESY AND GEOPHYSICS

  17. Different network configurations INSTITUTE OF GEODESY AND GEOPHYSICS Cofactors of xp, yp, dut1 xp = 3.9 µas yp = 8.8 µas dut1 = 0.5 µs 0.0544 -0.0606 0.0238 0.0689 -0.0360 -0.0280

  18. Different network configurations INSTITUTE OF GEODESY AND GEOPHYSICS

  19. Different network configurations INSTITUTE OF GEODESY AND GEOPHYSICS Cofactors of xp, yp, dut1 xp = 11.1 µas yp = 10.8 µas dut1 = 0.3 µs 0.0253 -0.0223 -0.0294

  20. Different network configurations INSTITUTE OF GEODESY AND GEOPHYSICS

  21. Different network configurations INSTITUTE OF GEODESY AND GEOPHYSICS Cofactors of xp, yp, dut1 xp = 182.1 µas yp = 193.1 µas dut1 = 4.7 µs 0.3193 0.7266 -0.3207

  22. Different network configurations INSTITUTE OF GEODESY AND GEOPHYSICS

  23. Different network configurations INSTITUTE OF GEODESY AND GEOPHYSICS Cofactors of xp, yp, dut1 xp = 12.8 µas yp = 16.0 µas dut1 = 0.6 µs 0.1869 0.3225 -0.3689

  24. 24 hour sky plots – changed sources INSTITUTE OF GEODESY AND GEOPHYSICS Cont 05 day 4 Only A & B Sources

  25. 24 hour sky plots – changed sources INSTITUTE OF GEODESY AND GEOPHYSICS Cont 05 day 4 Only A & B Sources

  26. Two small antennas at one station INSTITUTE OF GEODESY AND GEOPHYSICS Advantage: • higher observation density • better determination of systematic effects • one frequency standard • change the code in OCCAM for one clock • one more local tie

  27. Conclusions and outlook INSTITUTE OF GEODESY AND GEOPHYSICS • observing strategies and scheduling • - 16 station networks • - 32 station networks • antenna configuration • - identical antennas at all sites • - many small antennas vs. few large antennas • network geometry • - where to build new stations • troposphere and clock modeling • - low elevations vs. mapping function errors • - implication of multiple antennas at one station

  28. INSTITUTE OF GEODESY AND GEOPHYSICS Thanks for your attention

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