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Modelin g Phase and Cable Cal for ONSALA60 Dan MacMillan NVI/NASA/GSFC

Modelin g Phase and Cable Cal for ONSALA60 Dan MacMillan NVI/NASA/GSFC Per Bjerkeli Chalmers University, Sweden. Overview.

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Modelin g Phase and Cable Cal for ONSALA60 Dan MacMillan NVI/NASA/GSFC

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  1. Modeling Phase and Cable Cal for ONSALA60 Dan MacMillan NVI/NASA/GSFC Per Bjerkeli Chalmers University, Sweden

  2. Overview • The RDV experiments (6 per year) use the 10 station VLBA network plus 9-10 of our geodetic antennas. Currently phase cal is not available at the correlator for the non-VLBA antenna • Dependence of cable delays on the direction that an antenna is observing => Bias in estimated station coordinates • The cable wrapping at Onsala causes cable stretching that varies ~linearly with azimuth => 10-12 mm bias if cable cal is applied with no phasecal.

  3. OnsalaPhasecal Group and Cable Delay Phasecal group delay (10-11 sec) vs. azimuth from a year of Europe sessions Cable delay (10-11 sec) vs. azimuth from a year of Europe sessions

  4. Bias of RDV Onsala Baseline Lengths (Relative to Trend of All Other Sessions) Model 1 : Phase Cal = 2 * Cable Cal Model 2 : Azimuth/Temperature dependent models for Phase Cal and Cable Cal

  5. Instrumental group delay for the radio source Instrumental group delay for phase cal Correcting the radio source group delay with the phase cal group delay will overcorrect by –τpc. Cable cal correction = + τpc If there is no phase cal then assume that the phase cal and IF cable delays are the same => Correction = - τpc

  6. Phase Cal and Cable Cal Models • A year of EUROPE sessions (Jan. 2001 to Feb. 2002) were analyzed • Cable cal and Phase cal were extracted and fit with functions of azimuth, temperature, and elevation (ϕ< π) (ϕ> π) where ϕis azimuth and ε is elevation and T is temperature.

  7. a1 a2 a-coefficients for cable cal model as a function of temperature.

  8. a1 a2 a-coefficients for phase cal model as a function of temperature.

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