GPS Orbits

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GPS Orbits

• Jim Rohde, Bob Dulaney, Bill Kass, Steve Hilla
• National Geodetic Survey 2005 Convocation
• October 24-28, 2005
• Silver Spring, Maryland
• Holiday Inn
• 8777 Georgia Avenue

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Improvements to Orbit Processing in 2004/2005

• Stars Procedure Added redundant baselines by
  processing sub-networks and combining their
  normal equations
• Integer phase ambiguity fixing
• Moved production from HP to SUN x86 platform
• Orbit adjustment done more rigorously (ADJEPH)
• Fixed pole tide sign error
• Improved sub-daily EOP model
• Absolute Antenna Phase Center Offsets and PCVs
• Monuments as Reference Points (future)
• Updated Ocean Tide Loading Model (future)

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Multiyear CORS

• Motivation
• To provide long-term consistent solution of all
  data
• Results used for CORS coordinates and velocities
  realization of NSRS
• Implement recent improvements in GPS Data
  Processing
• Time Span 1994 through 2005
• Reference Frame IGb00 IGS realization of ITRF00

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Multiyear CORS (cont.)

• Procedure
• Streamline processing to fit with routine
  operations and avoid repeated reprocessing
• Step 1 Daily Global Solution orbits, EOPs, IGS
  and some CORS site positions solutions stacked
  weekly for the IGS
• Step 2 Daily CORS Solution CORS and some North
  American IGS site positions solutions stacked
  weekly for NAREF
• Step 3 Daily Multiyear Solution combination of
  all normal equations for orbits, EOPs, and all
  IGS and CORS site positions

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Multiyear CORS (cont.)

• Step 4 Weekly Multiyear Solution Stack 7 daily
  multiyear solutions and archive results
• Step 5 Full Multiyear solution Stack all weeks
  together to solve for site velocities
• Schedule Begin processing January 2006,
  complete in 3-6 months

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