Automatic Processing with GAMIT

1. Automatic Processing with GAMIT sh_gamit

2. Overview • Motivation for sh_gamit • an automatic processing script • runs GAMIT from RINEX files to H-files • How to set up sh_gamit • Running sh_gamit • Getting input correct makes runs more robust • Options in sh_gamit • User controls GAMIT/GLOBK Tutorial 2

3. Motivation for sh_gamit • Increase in amount of GPS data • requires autonomous processing • GAMIT uses many files • sh_gamit manages them automatically • Successful with both continuous and campaign data GAMIT/GLOBK Tutorial 2

4. What sh_gamit does • Checks tables (e.g. polar motion/UT1) for valid time range • Creates any directories that are needed. • Begins execution in the processing directory. • Get new tables by ftp if needed • Checks orbit files by ftp if needed GAMIT/GLOBK Tutorial 2

5. What sh_gamit does (2) • Finds raw data files and translates them into RINEX format using teqc • Finds RINEX-format data files • Gets any missing files from the ftprnx entries with ftp • Creates a daily processing directory • Creates links in day directory to data files • Executes GAMIT run in day directory GAMIT/GLOBK Tutorial 2

6. What sh_gamit does (3) • Plots one-way phase residuals and converted to images in GIF format • optional • GIF files are much smaller than postscript files • Updates processing history file GAMIT/GLOBK Tutorial 2

7. What sh_gamit does (4) • Sends an email message to you (not Simon!) with important summary information • number of sites • disk space remaining • best and worse RMS scatters • RMS fit from GAMIT runs • sites with large or no adjustments GAMIT/GLOBK Tutorial 2

8. What sh_gamit does (5) • Compresses, archives or deletes intermediate files as selected by the user. • Begins processing next day’s data • Continues until fatal error or all requested days are processed. GAMIT/GLOBK Tutorial 2

9. What sh_gamit does not do • Estimate velocities • The dishes • Think GAMIT/GLOBK Tutorial 2

10. Basic example • sh_gamit -d 1998 240 -orbit SIOF -expt emed -eops usno • process GPS data from day 240 of 1998 (Aug 28) • use any data in the local rinex directory • ftp data for sites specified by the user • optionally scan multiple directories to find data • use Final orbit estimate from Scripps Institution of Oceanography (SIO) • use EOP data from US Naval Observatory (USNO) [IERS Bulletin A] • Name the run “emed" • identify files • select data GAMIT/GLOBK Tutorial 2

11. Running sh_gamit • List options • sh_gamit -help • Select days of data to process • -d yr days • where yr and days are the data to be processed e.g., -d 1997 153 156 179 • -s yr d1 d2 • where d1 is start day and d2 is stop day to be processed e.g. 1997 153 178 • -r day • where day is number of days before current date. GAMIT/GLOBK Tutorial 2

12. sh_gamit options • -expt • 4 char name of experiment/solution being run [Default expt] • -orbit • Type of orbit to use. [Default SIOF]. Optional second argument gives the day-of-year for the orbit if not the same as processing day • -orbt • 4 char ID for orbit files. [Default 4 char extracted from the orbit selected] • -eops • Name of EOP series to use. (bull_b, bull_a, etc.) [Default usno] GAMIT/GLOBK Tutorial 2

13. sh_gamit options (2) • -sessinfo • Session - sampling interval, number of epochs, start time (default 30 2880 0 0) • -rx_doy_plus n • Search RINEX file names this many days into the future for current-day data • -rx_doy_minus n • Search RINEX file names this many days into the past for current-day data • -xsite list • List of sites to be excluded from the processing. GAMIT/GLOBK Tutorial 2

14. sh_gamit options (3) • -netext <char> • add network suffix <char> to day directories. i.e. 035r • -yrext • add year prefix to day directories. Ie 1997_053 • -pres • Plot gamit residuals as skyplots <Y/N/E>. YES, NO, ELEV. [Default N] • -nogifs • Do NOT create skyplot GIF graphics files GAMIT/GLOBK Tutorial 2

15. sh_gamit options (4) • -copt [file types] • Compress remaining files for each dayserve when d [Default x k autcln.out] • -aopt [file types] • Copy the specified files for each day to the directory specified by –archivepth • -dopt [ file types] • Delete specified files after processing each day. [Default c] • -mailto • Name of user and machine to send results summary. (e.g., simon@wegener.mit.edu) GAMIT/GLOBK Tutorial 2

16. sh_gamit options (5) • -snrres • Calculate theoretical phase residuals from SNR. Requires raw data or RINEX with valid SNR values. • -noacc • Do not exclude satellites base on accuracy codes in the .sp3 file. [Default exclude] • -xver char • 1-character x-file version (6th character of x-file). [Default is single-digit year] • -noftp • Use this option if no ftp download connections are available. GAMIT/GLOBK Tutorial 2

17. sh_gamit options (6) • -remakex Y/C/N • Y - Remake x-files without checking. • C - Remake x-file if orbit and session.info are incompatible and all RINEX files are available [Default C] • N - Don't remake x-files under any circumstances GAMIT/GLOBK Tutorial 2

18. sh_gamit options (summary) • Most of the sh_gamit options are not normally used and are related to processing old GPS data or reprocessing 'failed' days. • Main options will be used in tutorial GAMIT/GLOBK Tutorial 2

19. Before running sh_gamit • Create and fill templates directory • cd expt; cp -r ~/gg/templates . • Modify your files • cd expt/templates • edit templates/process.defaults • edit templates/sites.defaults • Create and fill "local" data directories • mkdir rinex • mdir raw • Ready to go GAMIT/GLOBK Tutorial 2

20. process.defaults • Normally only needs a little modification: • Default mailto address • Change directories where rinex and raw data may be found • Change the paths to: • gs (ghostscript) • convert (ImageMagik program to convert postscript to gif images). • These changes could be made permanently at each institution. They depend on machine setup) GAMIT/GLOBK Tutorial 2

21. sites.defaults • File specifies other sites to be used in processing and how sites should be treated. • Format: • site expt options • expt is 4-character code for experiment • options given below • Main options: • ftprnx - ftp Rinex data • ftpraw - ftp raw dat GAMIT/GLOBK Tutorial 2

22. Options in sites.defaults • localrx • Used to name sites that should be used from local rinex directories. If given only these sites are processed from the found files • xsite • Used to name sites that should not be used or not used for certain time spans • xstinfo • Ignore this site while automatically updating station.info file after successful solution • If a site is not in this list, then information about the antenna type and height will be extracted from the RINEX file GAMIT/GLOBK Tutorial 2

23. How high was that antenna? • If the station.info file is absent from the tables directory, then sh_gamit will use the header information from the RINEX file • The file called guess_rcvant.dat will be used to translate the entries in the RINEX file to codes that GAMIT knows. • If this fails, then GAMIT will stop 'fatally' • Antenna height errors can be corrected downstream in GLOBK, but errors in identifying the antenna type can not be corrected (phase center variations) GAMIT/GLOBK Tutorial 2

24. Controlling GAMIT • Two main files may need to be changed depending on data being processed • sestbl. • sets parameters for the sessions being processed • sittbl. • sets parameters for individual sites and defaults for sites • Both files reside in the tables directory • Links in day directories point to them. • “Standard example” versions of these files are for regional, bias fixed solutions. GAMIT/GLOBK Tutorial 2

25. Apriori station coordinates • Estimating them is a multi-step process • generated from GLOBK (.apr) format apriori file with positions and velocities for each day • GAMIT reads L-file with geocentric spherical lat/long/radius but no time dependence • Apriori coordinates need to be good (discussed Lecture 3) GAMIT/GLOBK Tutorial 2

26. Summary • The sh_gamit script provides a robust method for processing GPS data automatically and autonomously • Initial setup sometimes has problems, but once the first day of data runs without an error, the remaining days usually follow easily GAMIT/GLOBK Tutorial 2