1 / 16

VLBI2010 Simulations

VLBI2010 Simulations. Dan MacMillan NVI Inc. NASA/GSFC GGOS Working Group on Ground Networks and Communications December 12, 2007. Overview Simulation procedure and models Comparison between observed and simulation results VLBI2010 antenna slew rate simulation Network simulations.

krista
Télécharger la présentation

VLBI2010 Simulations

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. VLBI2010 Simulations Dan MacMillan NVI Inc. NASA/GSFC GGOS Working Group on Ground Networks and Communications December 12, 2007

  2. Overview • Simulation procedure and models • Comparison between observed and simulation results • VLBI2010 antenna slew rate simulation • Network simulations

  3. Simulation Procedure • Ran simulation observation files from observing schedules for a given network with the VLBI SOLVE analysis program • Performed Monte Carlo simulations using simulated noise delays generated from models of atmosphere, clock, and observation noise • - wet zenith delay random walk • - turbulent troposphere delay model • Computed RMS precision (scatter of estimated parameters) of Earth orientation and scale estimates from the series of Monte Carlo runs

  4. Comparison of observed and simulation scatter for CONT05 R&D series (15 continuous days)

  5. Antenna slew rate study • 16 site network • turbulent troposphere model • observing schedules generated for antennas with different • azim/elev slewing rates • azimuth rates from 1.5 deg/sec to 12 deg/sec • high observation rate schedules: 100-120 scans/hour/site

  6. Significant improvement between azimuth slew rates of 1.5 and 4.5 deg/sec but not beyond 6 deg/sec Alternative estimation strategies and better observation sky coverage may allow one to take advantage of higher slew rates

  7. Generated 24-hour observing schedules for a 32-site network and for 24-site, 16-site, and 8-site subset networks • Troposphere noise delays in simulation were turbulence model delays (same turbulence parameters for all sites)

  8. Conclusions (preliminary) • At present observed precision is underestimated by • simulations by a factor of ~ 2/3 • Length and vertical precision (scatter of simulation estimates) • are improved as antenna slew rates increase up to • ~ 4-6 deg/sec but not significantly for higher rates • Precision of scale and EOP improves by a factor of ~2 as • network size increases from 8 to 32 sites • Precision of scale and EOP improves also by a factor of ~2 • as the rate of data acquisition increases from 2 Gbps to • 32 Gbps

  9. Future Work 1) Improve modeling for simulated delay noise - improve turbulence modeling; speed up algorithm - add in models for other effects, e.g. antenna thermal deformation, troposphere mapping function error 2) Investigate estimation strategies to take advantage of higher observation rate schedules 3) Make time series of VLBI normal equations with Geodyn for new observing schedules for SLR combination 4) Analyze precision of VLBI-only TRF solutions using time series daily observing sessions

  10. Site network versus antenna specifications • VLBI2010 antennas • VLBA antennas operating at current data rate of 128 Mbps • VLBA antennas at data rate of 4 Gbps expected in ~2years • Advantages of VLBI2010 system • higher precision of the delay observable (4 ps versus 10-30 ps) • ability to tune continuously the observing frequency within bands and avoid S-band interference • replaces the aging equipment of the current system.

  11. Troposphere delay noise as wet zenith delay randomwalk => VLBI2010 network has best simulation precision

  12. Troposphere delay noise from turbulence model => VLBI2010 network has best simulation precision

More Related