1 / 25

HIGARUS 08

HIGARUS 08. Solar Disturbance of GPS Satellite Orbits. Merita Halili Orhan Veliu. 06 june 2008. Introduction. HiGarus ’08 -Continuation of previous work Project goal Effect of high solar activity on: GPS satellite orbit positions Ground positions. Sun Activity. 11 year cycle

ayla
Download Presentation

HIGARUS 08

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. HIGARUS 08 Solar Disturbance of GPS Satellite Orbits MeritaHalili Orhan Veliu 06 june 2008

  2. Introduction • HiGarus ’08 -Continuation of previous work • Project goal • Effect of high solar activity on: • GPS satellite orbit positions • Ground positions

  3. Sun Activity • 11 year cycle • Number of sunspots • 24thcycle • Geomagnetic storms • Solar radiation storms • Radio blackouts Solar Storms

  4. Solar activity affects: • Humans in space • Satellite operations • Aircraft operations • Power and communications • Climate change

  5. Selection of solar storms • SWPC archive • Storms(G3 to G5 and S3 to S5) • Calculate and compare • Broadcast and precise satellite orbit positions • Broadcast and precise ground positions

  6. PositionDetermination • Broadcast: • Satellite orbits computed using orbit parameters derived from ephemerides • Satellite clock error parameters • Correct the pseudoranges for satellite clock error • Least Square Adjustment to compute receiver position • Precise: • Precise orbits provided from IGS website • Interpolate to required epochs • Least Square Adjustment to compute receiver position

  7. Equipment • GJOV Reference Station Consists of: • Archive with stored 24/7 raw-data, since July of 2000 • GNSS Antenna • Two dual-frequency receivers • Two computers, each connected to a receiver • Appropriate software applications Does: • Tracks the number of and the status of all visible satellites and stores the data transmitted by the satellites. • Displays receiver’s current position and time. • Downloads and stores raw‐data measurements • Transmits the data for “real time” positioning.

  8. Software • Receiver software • Geodetic Base Station Software (GBSS) • PC-CDU • tps2rin • Programming • Microsoft Visual Basic 2005 Express Edition • FreeBasicIDE – Fbide • Other • Word, Excel, Access, Visio, …

  9. Data Formats • Broadcast ephemeris • Binary format • RINEX format (ASCII) • IGS precise orbits • SP3 format (ASCII)

  10. Parameters and Assumptions • Study Analysis Period • Start/end time • 24 hours, after the reported end of storm • Sampling Interval • Five-minute interval • One-minute interval • One-second interval • Satellite antenna phase center offset • WGS84 vs. ITRF

  11. Data Processing Steps Broadcast position • Generate a list of required epochs • Extract visible satellites/observed pseudo-ranges • Extract broadcast ephemeris • Compute broadcast orbit • Compute broadcast receiver position Precise position • Interpolate to epoch of observation • Compute precise orbit • Compute precise receiver position Compare positions • Compare broadcast and precise orbits • Compare broadcast and precise receiver positions Analyze Errors • Analyze orbit errors • Analyze receiver position errors

  12. Written Programs • Visual Basic 2005 and FreeBasic • Short programs • Comment the source code • Document program • dependencies

  13. Programs, Process Flowchart

  14. Difficulties • Non-standard RINEX • Huge amount of data to process • Many parameters in the RINEX - files

  15. Results • Satellite orbit positions • Ground positionsStudyperiods: • Storm day • Day after the storm • Clear day with no solar activity • Short intervals

  16. Storm Day - 30.10.2003 06:00PM -09:00 PM (G4) 09:00 PM -12:00 AM(G5) Satellites position 30.10.2003Difference between broadcast and precise ephemeris on X 5 minutes interval from 01:00AM until 11:00PM , UT

  17. 30.10.2003 – 1 minuteinterval Satellites position 30.10.2003Difference between broadcast and precise ephemeris on X 1 minute interval from 01:00AM until 11:00PM , UT

  18. 30.10.2003 – 1second interval Satellites position (PRN07)30.10.2003Difference between broadcast and precise ephemeris on X,Y,Z 1 second interval, UT

  19. Storm Day – 08.11.2004 Satellites position 08.11.2004. Difference between broadcast and precise ephemeris on Y 5 minutes interval from 01:00AM until 11:00PM , UT

  20. Day afterthe storm – 09.11.2004 Satellites position 09.11.2004. Difference between broadcast and precise ephemeris on X 5 minutes interval from 01:00AM until 11:00PM , UT

  21. Cleardaywithout storm Satellites position 26.12.2003Difference between broadcast and precise ephemeris on X 1 minute interval from 01:00AM until 11:00PM , UT

  22. Ground position – storm day Ground positions 30.10.2003Difference between broadcast and precise ephemeris on X .Y, Z 1 second interval from 01:00AM until 02:00AM , UT

  23. Conclusions GPS satellite orbits, during the selected study periods, do not tend to be disturbed by geomagnetic or solar radiation storms.

  24. Recommendations • Detailed study of solar storms • Longer study periods • Advanced programming • Advanced analysis tools • Phase pseudo-range measurements • Include also other GNSS

  25. For more information visit: http://hovedprosjekter.hig.no/v2008/iia/geo/higarus-08/

More Related