GPS Data Processing Using
GAMIT/GLOBK and TRACK
9-13 January 2012
Montserrat Volcano Observatory, Montserrat, West Indies.
This
workshop will include both static and kinematic processing of GPS data with an
emphasis on regional tectonics and volcano monitoring. It will include lectures
and one-on-one tutoring of both continuous and survey-mode measurements;
defining, global, regional, and local reference frames; temporal and spatial
filtering of time series; modeling tropospheric, antenna, and loading effects
in height estimates; combining solutions to estimate post-seismic and long-term
crustal deformation; handling step-displacements due to earthquakes and
instrument changes; developing an error model for velocity estimates, and
high-rate GPS for seismic surface waves. Participants will be expected to have
exercised the software on their own before the workshop and should bring
laptops with the software installed or with remote access to their own labs.
Instructor: Tom Herring, MIT
Schedule
|
Day
|
Time
|
Topic
|
|
|
Mon
|
8:30-10:00
|
Course logistics Introduction
to GPS
|
L01
|
|
|
10:30-noon
|
GAMIT Standard Processing
|
L02
|
|
|
13:30-15.00
|
GLOBK Overview
|
L03
|
|
|
15.30-17:00
|
Tutorial session
|
|
|
|
|
|
|
|
Tues
|
8:30-10:00
|
Modeling details
|
L04
|
|
|
10:30-noon
|
Reference Frame Realization
|
L05
|
|
|
13:30-15.00
|
Statistics of time series
|
L06
|
|
|
15.30-17:00
|
Tutorial session using tsview, tsfit and tscon
|
|
|
|
|
|
|
|
Wed
|
8:30-10:00
|
Introduction to Track commands
|
L07
|
|
|
10:30-noon
|
Methods of tuning track
|
L08
|
|
|
13:30-15.00
|
TrackRT installation and set up
|
L09
|
|
|
15.30-17:00
|
Tutorial
|
|
|
|
|
|
|
|
Thur
|
8:30-10:00
|
Utility programs and scripts
|
L10
|
|
|
10:30-noon
|
Globk Prototyping tools
|
L11
|
|
|
13:30-15.00
|
GPS Meteorological application
|
L12
|
|
|
15.30-17:00
|
Tutorial session
|
|
|
|
|
|
|
|
Fri
|
8:30-10:00
|
Review of issues and questions (prepared
based on comments)
|
|
|
|
10:30-noon
|
Discussion and tutorial
|
|
|
|
13:30-15.00
|
Tutorial session
|
|
|
|
15.30-17:00
|
Wrap-up session
|
|
Notes
and data sets
Mon 8:30-10:00 Course
logistics Introduction to GPS L01
In
this lecture we go through the basic layout of the short course. We also
introduce some of the basic concepts in GPS data processing, which we will
revisit in later lectures. We look at the basic GPS observables and examine
those contributions that are most uncertain in processing data. The main
conclusions from this lecture are that high precision GPS requires external
information in addition to just the GPS data and orbit information. In the
current processing methods, all of the external information needed by GAMIT is
automatically obtained but an Internet connection is required for access to
information in international data archives.
Montserrat_Lec01_Intro.pptx Montserrat_Lec01_Intro.pdf
10:30-noon GAMIT
Standard Processing L02
In
this lecture we look at daily processing using GAMIT. Nearly always the shell
script sh_gamit is used for this processing. We will
look at the directory structures that are normally used and the main functions
and programs that are used in daily processing. We then look at the files that
are important, and need user input, that are used in the processing. These
files include station information, coordinates and velocities for stations, and
other files that need to be kept up to date. We also look at the summary files
that are generated and examine how to interpret these files. We also look at
residual plots, which can be illustrative of problems in data processing.
Finally we look at problems that can happen during processing and add some
suggestions on how to solve these problems.
Montserrat_Lec02_gamit.pptx Montserrat_Lec02_gamit.pdf
13:30-15.00 GLOBK Overview L03
in
this section we review the main features of globk and
glred. It is important to note that glred is a simple program that allows multiple runs of globk and is used typically for time series generation. The
topics we cover are the basic flow from daily gamit
processing results (hfiles) to the results generated
with globk.
We briefly review Kalman filtering and we look at the globk files and the estimation rules used. The program glorg which
can be either run by itself or from within globk, is
used to define the origin and orientation of the reference frame for the globk results.
We examine the output options and briefly look at the sh_glred script, which is a convenient way of invoking globk and its ancillary programs.
Montserrat_Lec03_globk.pptx Montserrat_Lec03_globk.pdf
15.30-17:00 Tutorial session
In
this 1st tutorial we will do standard gamit
processing using data in southern California. The stations used here are only a
small set of those that are available through the Unavco
archive. On day 166 of 2010 an aftershock of the El Mayor Cucapah
earthquake that occurred in April of 2010, occurs. On
this day we will use the sessinfo option in sh_gamit to break the day before and after the quake.
Included in the same data set are hfiles from many
more days of data that we will use in the globk
tutorial.
Montserrat_Tut01_basic.pptx Montserrat_Tut01_basic.pdf
BajaTutorial.tar.gz (210
Mbytes)
_______________________________________________________________________
Tues 8:30-10:00 Modeling
details L04
In
this lecture we look in more details at some aspects of modeling data in GPS
processing. We will look at effects
that can be considered signal and sometimes noise in GPS processing. The basic
areas we discussed our atmospheric delay modeling and signal scattering, and
loading affects from the ocean, atmosphere and water.
Montserrat_Lec04_models.pptx Montserrat_Lec04_models.pdf
10:30-noon Reference
Frame Realization L05
In
this lecture we introduce the concepts of reference frame realization and the
methods used in globk a to generate results in a
specific reference frame. As we saw in earlier lectures, sites are affected by
loading, mostly in the vertical direction, and these effects influence the
reference frame realization. We look at ways of handling this in globk. We also examine local reference frame realizations
and the way that earthquakes need to be treated in large analyses.
Montserrat_Lec05_RefFrame.pptx Montserrat_Lec05_RefFrame.pdf
13:30-15.00 Statistics of
time series L06
We
review the sources of noise in GPS position determinations and we look at some
of the methods used to characterize noise. We look at the Òrealistic sigmaÓ
algorithm that is implemented in globk and tsview. We also
look at some methods that can be used to judge the quality of the uncertainty
estimates derived by different techniques. Finally we look at the tools that
are available in gamit/globk
for error analysis and assessment.
Montserrat_Lec06_ErrorMod.pptx Montserrat_Lec06_ErrorMod.pdf
15.30-17:00 Tutorial session
using tsview, tsfit and tscon
This
tutorial session will be used to look at results from user data sets and also
from the data set analyzed yesterday. Included in that data set at timeseries files that can be used to look at the statistics
for the Salton Sea data.
_______________________________________________________________________
Wed 8:30-10:00 Introduction
to Track commands L07
This
lecture looks at the basic methods used by the kinematic processing program
track. We look at the equations that are used for the wide lane statistics and
how these are used for ambiguity resolution. We look at the basic inputs for
the program and how to run it. We then look at the statistics that should be
checked and the basic commands that often need modification from the default
values. We'll look at these more in the next lecture. We then look at some
examples of track results. The tutorial session will include some of the data
shown here.
Montserrat_Lec07_track.pptx Montserrat_Lec07_track.pdf
10:30-noon Methods of
tuning track L08
In
this lecture we look at the file outputs from track and how to interpret them.
We then look at some of the track commands in more detail. We conclude by
noting those options in track that often need to be modified from the default
values. Our recommendation is to use the defaults initially and then tune based
on those solutions.
Montserrat_Lec08_tracktuning.pptx Montserrat_Lec08_tracktuning.pdf
13:30-15.00 TrackRT installation and set up L09
In
this lecture we look at the use and installation of the real-time version of
track called trackRT. The real-time system uses the BKG
program BNC to cast the GPS data to a real-time port that can be read by trackRT. The installation of the program is complicated by
its use of the Nokia QT system and that the makefile
needs to be modified to show the location this system. Installation on Linux
operating systems is relatively straightforward. There are two versions of the
program depending on which version of BNC is used. TrackRT
is used for versions 2.5 and greater. Track RTB (binary) is used for earlier
versions of BNC. We also discuss the trackRTr program
that uses RINEX datafiles.
Montserrat_Lec09_trackRT.pptx Montserrat_Lec09_trackRT.pdf
15.30-17:00 Tutorial
There
are two tutorial folders in the trackTutorial folder.
The BajaEQ folder contains high rate (5 Hz) GPS data
collected at the time of an earthquake, and the kineMIT
folder contains kinematic data collected at MIT. These later data can be
processed in short baseline mode or in long baseline mode using one of its data
from Algonquin Park in Canada (ALGO).
Montserrat_Tut03_track.pptx Montserrat_Tut03_track.pdf
trackTutorial.tar.gz (157 Mbytes)
_______________________________________________________________________
Thur 8:30-10:00 Utility
programs and scripts L10
This
lecture covers utility programs and scripts. These are organized into
preprocessing and organization scripts, scripts that are used inside sh_gamit but are also useful standalone, and scripts that
are useful for evaluating results. We also briefly review UNIX shell programs
that are used extensively and are good to be familiar with.
Montserrat_Lec10_utilities.pptx Montserrat_Lec10_utilities.pdf
10:30-noon Globk Prototyping tools L11
In
this lecture we look at tools that can be used to test large globk solutions.
These tools allow timeseries to be analyzed
for discontinuities from equipment changes and earthquakes and allow earthquake
files to be developed that can be used in globk.
These programs can also be used to realign reference frames very rapidly and to
fit parameters for periodic signals and earthquakes. The a priori coordinate
files generated here can contain the extended entries (periodic signals,
earthquake the seismic signals) that can be used in globk.
For large data sets these prototyping tools allow efficient testing of a globk run that might take one or two days to execute.
Montserrat_Lec11_Protoptype.pptx Montserrat_Lec11_Protoptype.pdf
13:30-15.00 GPS
Meteorological application L12
This
lecture reviews some of the meteorological applications of GPS and we will
discuss some of the utilities that can be used in gamit
for meteorological applications.
Montserrat_Lec12_MetApps.pptx Montserrat_Lec12_MetApps.pdf
15.30-17:00 Tutorial session
There
is no specific tutorial for this day. We will work on the data sets from
previous days depending on the interests of the group. It is expected that
different students will work on different projects and during this session we
will have discussions informally. If an interesting issue is encountered then
we may take time to present those results to the whole group.
_______________________________________________________________________
Fri 8:30-10:00 Review
of issues and questions (prepared based on comments)
The
contents of this lecture will depend on questions and issues the raised during
the first 4 days the course.
Each student is expected to submit at least one question or suggestion
of the material to be covered in this class.
10:30-noon Discussion
and tutorial
This
session will also follow on from the morning session addressing issues that
have been encountered either in the tutorial data sets or
13:30-15.00 Tutorial session
Tutorial
session will follow from studies done earlier in the course.
15.30-17:00 Wrap-up session
_______________________________________________________________________
