1. Solar Disturbance of GPS Satellite Orbits Merita Halili Orhan Veliu 06 june 2008

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

3.  11 year cycle  Number of sunspots  24 th cycle  Geomagnetic storms  Solar radiation storms  Radio blackouts Solar Storms

4.  Humans in space  Satellite operations  Aircraft operations  Power and communications  Climate change

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

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

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

9.  Broadcast ephemeris o Binary format o RINEX format (ASCII)  IGS precise orbits o SP3 format (ASCII)

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

11. Broadcast position 1. Generate a list of required epochs 2. Extract visible satellites/observed pseudo-ranges 3. Extract broadcast ephemeris 4. Compute broadcast orbit 5. Compute broadcast receiver position Precise position 6. Interpolate to epoch of observation 7. Compute precise orbit 8. Compute precise receiver position Compare positions 9. Compare broadcast and precise orbits 10. Compare broadcast and precise receiver positions Analyze Errors 11. Analyze orbit errors 12. Analyze receiver position errors

12.  Visual Basic 2005 and FreeBasic o Short programs o Comment the source code o Document program dependencies

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

15.  Satellite orbit positions  Ground positions Study periods:  Storm day  Day after the storm  Clear day with no solar activity  Short intervals

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

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

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

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

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

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

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

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

24.  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/