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This presentation highlights the significant improvements made in GPS orbit processing between 2004 and 2005, focusing on enhancing accuracy and consistency. By implementing steps such as integer phase ambiguity fixing, orbit adjustment rigor, and fixing pole tide sign errors, the process has been refined for long-term data solutions. The use of redundant baselines, improved sub-daily Earth Orientation Parameters (EOP) model, and updated Absolute Antenna Phase Center Offsets ensure a reliable realization of the National Spatial Reference System (NSRS). The streamlined processing methodology includes daily global solutions stacked weekly for the IGS, supporting CORS coordinates and velocities. The schedule for implementing these enhancements began in January 2006, emphasizing efficiency and precision in the computation process.
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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
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)
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
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
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