GIPSY-OASISII Analysis using xt
Contents
1. SSH 2 Authentication Authentication required User name geodesy Passphrase Use plain password to log in C Use RSA key to log in Disconnect Now you are logged onto calipso through a secure network tunnel that will allow the x windows packets to be forwarded automatically to your local PC You see something like this when you log in E calipso uark edu Telnet SSH 2 lt ansi gt Commands Edit Options Help fusr openwin bin xauth creating new authority file export home geodesy Xauty Last login Thu Jan 61 1976 66 66 66 Sun Microsystems Inc SunOS 5 8 Generic February 2666 No mail Sun Microsystems Inc SunOS 5 8 Generic February 2666 calipso In order for the local Backspace key to map correctly to delete on the server type the following command at the calipso prompt calipso stty erase H Task 2 Preparing to Estimate a Network Solution using GOA Now that you have successfully connected to the server on which GOA resides you can start the lab exercise First you should change directory into lab1 do a directory list on your home directory the commands and output are shown below E calipso uark edu Telnet SSH 2 lt ansi gt Commands Edit Options Help geodesy geodesy geodesy geodesy geodesy You should see five sub directories listed in alphabetical order 1 ans 2 nav 3 obs 4 orbits and 5 raw Each of these contains the following 1 ans these are2. the results that I obtained when I processed the example you should use these to compare with your results later in the lab exercise 2 nav this directory contains the RINEX navigation files from five of the six CGPS sites that your will process in this exercise 3 obs this directory contains the RINEX observation data files for all six sites NB that this example has several different receiver types and file name formats 4 orbits this directory has the orbit clock and earth orientation data necessary to process the GPS data and 5 raw this directory should be empty initially but the RINEX files must be copied there in order for xt gipsy to execute properly As many of you may not be facile with basic UNIX commands here is a very brief primer Command Name Form Purpose cd change directory cd dir_name To move to another directory compress uncompress compress uncompress compress file uncompress file Compress or uncompress file using standard UNIX compress algorithm cp copy cp file file2 Copy file to file2 NB that you can use relative or full path names grep grep grep pattern files Look for specific text patterns ina single or multiple files Ip line printer Ip files Print the files to the device named Ip which in this case is the geod_lab_4500 Is list Is Get a directory listing NB that it doesn t
3. where one simply types individual commands at the prompt or by using a graphical user interface developed by Ken Hurst at JPL called xt gipsy which is based on the X windows system protocols As this will be our first use of GOA we will use xt gipsy In order for use to proceed we need to first initiate an X windows session on our PC Mac or UNIX LINUX workstation Simply logging on to the LINUX workstation or the Sun UltraSPARC10 will initiate the X windows server but if you are attempting to connect to calipso from a PC or Mac or need to run additional software as follows On a Windows XP machine start Xsession from main windows start menu ts Start 5 glen mobile1 cast u fim My Documents ia GEOL4733_labS doc 10 33 AM The Xsession program once started will automatically minimize itself You must right click on the X Session program and select Run gt Telnet This will bring up the window below Telnet Connect Host Interface Host calipso uark edu v Ok C Telnet C SSH 1 Port 22 Cancel SSH 2 Forwarding Disable Forwarding Select SSH 2 and enter the server name as shown above and then click OK This will cause the following screen to be presented Make sure you do not select Disable Forwarding otherwise the graphical commands from the server will not be displayed locally Enter the USERID and PASSWD information from above and again click OK
4. 0 000 BGGY CGPS site at Boggy Peak on Antigua geol3600 000 GEOL CGPS site at UPRM in Mayaguez PR harr3600 000 HARR CGPS site at Harris Lookout in Montserrat mvol3600 000 MVO1 CGPS site at the MVO north in Montserrat souf3600 000 SOUF CGPS site at S Soufriere Hills in Montserrat NNNNWN These sites are located on four different islands in the northeastern Caribbean The approximate distance from GEOL to HARR is 550 km Your RINEX data files use both the GOA naming convention e g O0dec25crol r0 rnx Z and the standard IGS naming convention e g bggy3600 00 0 Z Both naming conventions contain the necessary information to determine when and where the observations were obtained Also note that all the files are compressed and hence have a Z at the end of the name This means that the files have been converted from their original ASCII text format to a binary compressed UNIX format that is widely used throughout the world Under normal GOA operations files would have to be renamed to the form used for the CRO1 site and uncompressed prior to processing As we will see below xt gipsy will do both the file name translation and uncompressing for us automatically In addition to putting the data files in the appropriate place we also must make sure the station information database files which are used by GOA contain the appropriate information for each site The four files and their formats were discussed in class and you sho
5. 47 60 47 60 47 60 47 00 47 00 47 08 47 08 47 60 47 60 orbits orbits 2666 12 25 tdpc 2 orbits 2606 12 25 shad gt Shadow orbits 2666 12 25tpeo nml 2 gt tpeo nml calipso zcat calipso zcat obs orbits Now you are ready to start xt gipsy Issue the following command making sure that you 1192 64627 1773 35965 4710 802022 7570 21933 163607 21367 12875 87581 15233 33965 17339 64114 19158 36296 26657 25514 21868 84361 peci peci raw run the program in the background calipso xt gipsy amp You should see the following while xt gipsy is starting up and translating the filenames in the raw sub directory xtpanel HELCONE to xt gipsy HAIT Translating 7 filenanes 19644 59331 17786 37119 16228 863489 14412 32433 12362 11544 16116 67269 7692 25357 5147 66246 2517 75035 154 13985 2823 38583 raw gt TDPfile tpeo nml 1 done 19247 61437 26376 74499 21164 31668 21614 31997 21712 55216 21456 18298 26847 87685 19895 82418 18613 86143 17621 64265 15142 12665 Once completed the following screen will be presented to you xtpanel SE HELCOHE to xt gipsy ma Choose a STRATEGY 3 29306459 3 28781659 3 229247 62 3 11808232 2 95575843 2 74442947 2 48696546 2 18694994 1 84867 676 1 47716236 1 67787667 Now you are ready to choose a processing strategy from the Choose a STRATEGY menu Select fixed_precise
6. GEOL4733 Applications of GPS Geodesy in Geosciences Dept of Geosciences University of Arkansas G Mattioli Laboratory Exercise 5 GIPSY OASISIT Processing In this laboratory you will learn how to process data using GIPSY OASISII GIPSY GPS Inferred Positioning SYstem OASIS Orbit Analysis and SImulation Software This software is very complex and requires significant use over a long time to master Our goal is only to gain some basic level of familiarity with the GOA environment the required input files and its output The software was developed by engineers at NASA s Jet Propulsion Laboratory with some additional contributions academic scientists Nearly all the individual software modules within GOA are documented online The software is composed of binary executable code both ANSI C and Fortran 77 90 c shell and bourne shell scripts The latter may be modified by the end user if necessary but the former cannot GOA currently runs only under UNIX HP or Solaris or LINUX 186 operating systems Currently the UARK Geodesy Lab is running GOA release 2 6 update 1 under Solaris 8 patch level 10 02 on Sun Microsystems UltraSPARC10 and UltraSPARC60 There are numerous papers and references available outlining the theory use and application of GOA Two major sources are by far the most important however and copies of both are available in the Geodesy Laboratory Ozark Hall 27A B Webb F H Zumberge J F 1995 An Int
7. _orbit clock TDP Shadow and the following screen will be presented STRATEGY fixed_precise_orbit clock TDP Shadouw Choose a GOAL Directory export hone geodesy lab1 DONE log file nane strategy description i qregres nnl HELP xt gipsy log priority nice value qregres log rgfile AS_status vash nnl urefile start tine scratch dir 1 JAN 1980 00 00 00 0 tnp preprefilter log prefilter txt prefilter log batch txt phase txt Reference clock BGGY filter_force log ad Line postbreak log batch out postedt log postfitX log pointX txt edtpnt2_xX 1 J JAN 2020 00 00 00 0 set Fiducial stations postfit_final nio bias_free stacov anbigon nnl accune_fix nio solution interval sec snooth_fix nio update using touch anbigon2 log anbigon txt Execute bias _fix stacov Now let us select set Fiducial stations to pick BGGY as the fiducial site This effectively puts our solution in the BGGY fixed frame Select sites to constrain as fiducials BGGY 1 0d 7 Click on QUIT once you have fixed the a priori sigma for the BGGY position at 1 0d 7 km which is 0 1 mm On the right hand side of the main xt gipsy window there is a dialog box that lets you select a goal Each of these entries represents a specific step in the overall GOA processing Select wash nml for example and then click on about this goal to get information on that goal Your fina
8. for both the free and fix solutions Make sure you create a new directory in which to do the new processing Include the output with your lab Are the solutions the same or different Explain Once you have completed you lab please quit xt gipsy logout of calipso and quit the local X session program on the PC
9. he same file and the third command prints the file to the Geodesy Lab Color LaserJet4500 If any station is not present in the station information database files all three GOA will either give an incorrect position estimate or crash depending on what data are missing Examine the information for each site in the six station network Describe below what each field is and its purpose in each of the three sta_info files Task 3 Invoke xt gipsy and Estimate a Network Solution using GOA Under normal circumstances prior to the execution of xt gipsy one would be required to obtain from JPL by anonymous ftp the required orbit clock and earth orientation parameters lucky for you however I have already obtained the necessary data Move to the orbits dir and do a directory listing You should see the following E calipso uark edu Telnet SSH 2 lt ansi gt Commands Edit Options Help geodesy 2426 66dec25 itrfoo x geodesy 123775 2666 12 25 eci 2 geodesy 6 2666 12 25 frame geodesy 1336 2666 12 25 shad 2 geodesy 426538 2666 12 25 tdpc 2 geodesy 123954 2006 12 25 nf eci 2 geodesy 415686 2666 12 25 nf tdpc 2 geodesy 2563 2666 12 25tpeo nml 2 geodesy 2579 2666 12 25tpeo_nf nml 2 41 1 1 41 41 1 41 1 1 Note that there are two sets of orbit clock and earth orientation files fiducial and non fiducial and these are designated by nf corresponding to the non fiducial type Also shown is an ASCII file which allows one t
10. l goal should be bias_fix stacov This will produce a final solution that will have the phase ambiguities estimated and fixed between all the stations in our six station network Select this goal and click on execute This will initiate the GOA processing The processing of this network will take some time so you can relax and take a break will the CPU crunches the numbers If all goes well you will get a message indicating the final solution has been obtained Questions Examine the following log files qregres log smapper log postfit_final log and xt gipsy log What type of information is contained in each of these files and how is it useful to the GPS analyst Print the bias_free stacov and the bias_fix stacov files and label appropriately Describe the contents of each file and discuss why they are different Compare the bias_free stacov and the bias_fix stacov using the GOA utility station_diff and write the output to a file Print this file and include with you completed lab Now compare your results with those found in the ans sub directory Again write the results to a file and print to include with your lab Explain why the free and fix solution are different Task 4 Rerun xt gipsy using non fiducial orbits Complete all the same tasks that were done in Task 3 using fiducial orbits this time using the non fiducial files also found in the orbits sub directory Compare the solutions
11. o convert your final solution to one mapped into the ITRFOO O00dec25 itrf00 x This file corresponds to the x file and is only required if one uses the non fiducial orbit clock and earth orientation files The fiducial versions of these files correspond to a specific reference frame in which the fiducial sites were processed by JPL This frame is archived in the 2000 12 25 frame file Examine both these files either by printing them or by using more on the screen Discuss the implications of using the non fiducial versus fiducial approach below Prior to invoking xt gipsy we need to copy and rename the appropriate orbit clock and earth orientation files from the orbit sub directory to the main processing directory and name them appropriately In our first example we will process the data using the fiducial files The original and xt gipsy file names are shown below Execute the required UNIX commands NB that the files must be uncompressed Describe briefly what it file is and its function in GOA GPS processing 2000 12 25 eci gt peci 2000 12 25 tdpce gt TDPfile 2000 12 25 shad gt Shadow 2000 12 25tpeo nml gt tpeo nml Try the following command and then examine the contents of your directory calipso zcat orbits 2000 12 25 eci Z gt peci Your output should look like this E calipso uark edu Telnet SSH 2 lt ansi gt Commands Edit Options Help directory ascii text directory 47 60 47 08
12. require an argument man manual page man unix_command Get online info ona UNIX command or program more more more files Display the contents of a text file s page by page Use spacebar to advance remove rm file file2 Remove files Be careful there is not recovery once the files have been deleted First copy the entire contents of the lab1 directory to a directory with your name This will allow you to have only one userid but process the data independently This is done by executing the following command calipso cp R lab1 shane_lab1 Now change directory to your new directory and copy the RINEX observation files from the obs directory to the raw directory and do a directory listing Shown below are the commands and the expected output E calipso uark edu Telnet SSH 2 lt ansi gt Commands Edit Options Help geodesy geodesy geodesy geodesy geodesy raw geodesy 631263 66dec25cro1 r6 rnx 2 geodesy 962993 bggy3666 660 2 geodesy 792116 geo13666 660 2 geodesy 532396 harr3666 660 2 geodesy 943578 myvo13666 660 2 geodesy 680732 souf3666 660 2 NB that I executed the copy command using a wildcard which in this case was This caused all the files in the obs sub directory to be copied into the raw directory You should see six files each one corresponding a distinct CGPS site O00dec25crol rQ 7nx 2 CRO1 IGS CGPS site on St Croix USVI bggy360
13. roduction to GIPSY OASIS I Jet Propulsion Laboratory User Manual JPL Technical Document D 11088 California Institute of Technology Gregorius T 1996 GIPSY OASISII How it works Dept of Geomatics Univ of Newcastle upon Tyne U K self published These resources are not to be removed from the lab under any circumstances Class Notes from the JPL GIPSY OASISII class attended by Dr Mattioli in 1997 are also available and were the basis for the presentation in class with contributions from various authors including Y Bar Sever M Heflin K Hurst and F Webb Copies of these were provided to you during our previous lectures on GOA You should refer to the document called xt gipsy A Graphical User and Command Line Interface for Processing GPS data with GIPS Y OASISIT by Ken Hurst which was given to you in class Please read this carefully prior to starting this lab Task 1 Connecting to the UARK GOA server using SSH In order to use GOA you must have either network or direct access to the server on which the software resides This requires a userid and password All communication with the server if you are not directly logged onto to the console must be through a secure communications channel using SSH 2 secure shell protocol version 2 in which all network packets are encrypted during transport Server calipso uark edu Userid geodesy Password foobar GOA may be used either through a command line interface
14. uld have the documentation in your handouts The files are 1 sta_id the station identification file 2 sta_pos the station position file 3 sta_svec the station vector file and 4 pcenter the phase center offset file which maps the antenna type listed in the sta_svec file to the its appropriate phase center offset NB that GOA has specified physical offset datum for different types of antennae Choke rings are referenced from the base of the pre amp thus the height entered into the sta_svec file must be true vertical at the base of the pre amp All of these files may either reside in a location that may be accessed by all users or within a user specified location The default location is the goa sta_info directory The files located in goa sta_info are only editable by the superuser but may be read by anyone I have already entered the appropriate information in the general database files You should verify that this is correct and write all the information to a file and print Issue the following commands calipso grep CRO1 goa sta_info gt station_info calipso grep BGGY goa sta_info gt gt station_info etc for all the stations calipso Ip station_info Note that the first command finds all the instances of CRO1 in all the files residing in the sub directory goa sta_info and then writes that information into a new file called station_info The second command appends using the gt gt the information for BGGY to t
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