Geoscience 444

Practical Aspects of GPS Surveying

Photo of a geodetic benchmark in Honduras by Neal Lord

Kurt Feigl
Associate Professor
Department of Geoscience

Description of Course

Capsule statement of course

Global Positioning System surveying for field applications: Signals. Coordinate systems. Datums. Cartographic projections. Satellite orbits. Choosing hardware. Strategies for data collection and analysis. Assessing uncertainty. Geocoding satellite images. Integrating data with Geographic Information Systems. Emerging technologies.

Prerequisites

Calculus and/or elementary vector matrix algebra (Math 210, 211, 221 or equivalent) or consent of instructor
Some experience with field mapping, navigation, or orienteering is desirable.
Familiarity with computers and/or high-level programming/scripting languages is desirable.
This course is NOT open to freshmen.

LEVEL OF COURSE: ADVANCED

CROSSLISTING DEPARTMENTS

Civil and Environmental Engineering
Geological Engineering
Nelson Institute for Environmental Studies

CREDITS:

Number: two (2)
7-week modular class beginning week 10.
(2.5 hours of lecture per week) x (7 weeks) + 2 x (4-hour field exercises) = 25.5 hours of instruction

HOW TO REGISTER

GEOSCI       444-001 LEC (55572)     Pract Appl of GPS Surveying

G L E        444-001 LEC (45403)     Pract Appl of GPS Surveying

ENVIR ST     444-001 LEC (46124)     Pract Appl of GPS Surveying

GEOLOGY      444-001 LEC (55572)     Pract Appl of GPS Surveying

CIV ENGR     444-001 LEC (63268)     Pract Appl of GPS Surveying

EXPANDED COURSE DESCRIPTION

Positioning by multiple measurements of distance (trilateration).
How does GPS work?
How well does it work?
Field mapping exercise: mapping and plotting a campus trajectory.
Fundamental geodesy: ellipsoid, geoid, coordinates, datums, cartographic projections.
Review of Linear Algebra.
Choosing a surveying strategy: the tradeoff between cost and accuracy.
Receiver position from Code Observations (pseudoranges).
Baseline computation and M-files. Coordinate Changes and Satellite Position.
Receiver position from pseudoranges by two different methods. Clock offsets.
Receiver position from phase observations.
Kinematic and Rapid Static surveying.
Real Time Kinematic surveying.
Student presentations of surveying projects.

NEED FOR THIS COURSE

Many disciplines studying the Earth, its environment and anthropogenic impact on them involve mapping or sampling object in the field. The Global Positioning System allows anyone equipped with a receiver (costing as little as $100) to estimate their position coordinates (latitude, longitude and elevation) to within 10 meters easily. With a more sophisticated instruments and techniques, accuracies of better than 1 cm are possible. Applications range from scientific (e.g., measuring tectonic plates as they move) to the practical (“how do I get back to where I parked my car). If students are to apply these techniques (or supervise others to do so) in tomorrow’s world, they should understand the basic technical underpinnings of GPS.

RELATIONSHIP TO OTHER UW-MADISON COURSES

The proposed new course is complementary to, but distinct from, the following other courses, as described in the supplementary material: Geography 370, Geography 377 (Introduction to Geographic Information Systems), Geological Engineering 302 (Introduction to Electro-Optical and Microwave Remote Sensing Systems), Geological Engineering 303 (Introduction to Remote Sensing Digital Processing), Geological Engineering 304 (Remote Sensing Visual Image Interpretation). On the other hand, I could not identify any significant overlap with any courses in the undergraduate catalog for 2005-2007. In assessing overlap, it is important to distinguish between the two similar acronyms, GPS and GIS. The former stands for Global Positioning System and is the topic of the proposed course. The latter stands for Geographic Information System and is “downstream” in the flow of information.

WILL THIS COURSE MEET A REQUIREMENT FOR THE MAJOR IN YOUR DEPARTMENT OR ANOTHER DEPARTMENT?

YES, The course 444 does count towards the 34 credits of course work in Geology and Geophysics required for the major. It also counts toward the requirement of 12-15 credits of upper-level course work.

Syllabus

Learning Objectives

To understand the current abilities, future potential, and limiting factors of GPS surveys
To master the criteria for choosing instrumentation hardware and analysis software
To view practical examples applications of GPS surveying
To apply GPS surveying to a practical example of interest
To develop critical thinking skills, particularly in spatial reasoning about quantitative data
To develop the ability to work in a team, conceive and strategize a project
To make judgments of the tradeoff between accuracy and cost

How will students be evaluated?

Two problem sets involving data analysis with Matlab.
One proposal for a project.
Project, described above.
No final exam.

Schedule

Seven-week modular course beginning week 10 of Spring Semester, 2010.
Class will meet Tuesdays and Thursdays from 2:30 PM to 3:45 PM.
Location for all class meetings is Room 1249 of Engineering Hall (ENGR)
First meeting is 2:30 PM Tuesday March 16, 2010.
Field exercise I is from 1:00 to 5:00 PM Saturday April 10th, 2010
Field exercise II is from 1:00 to 5:00 PM Saturday May 1st, 2010
Student presentations of projects are tentatively scheduled for 6:00 PM - 9:00 PM Tuesday May 11th, 2010.
Office Hours: Tuesdays 4:00 to 5:00 PM in Room 1249 of Engineering Hall

List of Lecture Topics click here to download PDF file with reading assignments and schedule

First Class; positioning
How does GPS work? How well does it work?
Geometry of the Ellipsoid; Geodetic Reference System; Geoid, Ellipsoid and Datum; World Geodetic System 1984; Changing Datum
Preparing for a field survey
Field Exercise 1: Point Positioning with a single receiver
Introduction to Matlab: functions, scripts, plots, etc.
Review of Linear Algebra I: Vectors; Lengths and Dot Products; Planes
Review of Linear Algebra II: Matrices and Linear Equations; Heights by least squares; weighted least squares
Choosing a surveying strategy: the tradeoff between cost and accuracy. Expectations for student projects.
Receiver position from Code Observations
Precise point positioning for stationary receiver.
Field Exercise 2: Relative Positioning with three receivers
Precise point positioning for moving receiver
Relative positioning from phase observations for stationary receiver.
Rapid Static Positioning
Review Q & A.
Student presentations of surveying project

Description of Project

Working in teams of two, the students will use GPS receivers to perform a survey of interest to them. They will then present the results of the survey to the class in a short, 15-minute oral presentation, as a team of two. Examples of projects might include:

Locations of parking spots for a certain type of vehicle (e.g., bicycle, handicap van, etc) available on campus at the time(s) of the survey(s).
Establishing a grid for environmental research on University Lands, e.g. Arboretum
Monitoring the trajectory, including estimates of velocity and acceleration for recreational vehicles (e.g., bicycles, rowing shells, sailboats, canoes, skateboards, cross-country skiing, etc.)
Locating sampling, measurement, or observation points for geologic, biologic or anthropological research project.
Prior to undertaking the project, each student will write, as an individual, a brief proposal of the problem to be addressed and the technical approach for meeting it, including the trade-off between cost and accuracy.
Locations for procuring pizza near campus. Click here to download KMZ file for Google Earth.
Locations of bike racks on campus. Click here to download KMZ file for Google Earth.

Documentation

Textbooks

Strang, G., and K. Borre (1997), Linear algebra, geodesy, and GPS, xvi, 624 p. pp., Wellesley-Cambridge Press, Wellesley, MA. [$65.00]

Warning: ordering this book through the usual channels may be slow. Please allow enough time for delivery. If you are interested in taking this course, please order the book in January! You can order it directly from the publisher if you pay by check, but not credit card.

See http://www-math.mit.edu/~gs/books/gps.html

Leick, A. (2004). GPS satellite surveying. Hoboken, NJ, John Wiley.

Online Resources

Glossary of terms used in satellite navigation http://facility.unavco.org/data/glossary.html

Software

Computer Aided Engineering Center

Learn about this great resource, read the policy governing its use, and activate your account

Room 1249 in Engineering Hall

Matlab

Tutorials

Mathworks

Student Version

Mathworks MATLAB 7 Student Version R14 with Service Pack 3 (Student Sales Only) for Mac/Linux/Win CD. License Valid as long as the Student is a registered Student in a Degree-Granting Institution. http://techstore.doit.wisc.edu/product.asp?login=P&itemnum=C44072

Scripts

The Matlab scripts described in Strang and Borre's textbook are available free of cost from Strang and Borre at http://kom.aau.dk/~borre/matlab/
The Easy Suite - Matlab code for the GPS newcomer -- by Kai Borre. Matlab code for reading RINEX files, determining a pseudorange point position, calculating a carrier-phase baseline solution, doing a Kalman Filter baseline solution, checking for cycle slips and receiver clock resets, estimating ionospheric delay, plotting receiver clock drift, and more... The technical paper which describes this Matlab code is published in GPS Solutions, Volume 7, Number 1, 2003, pp 47-51, "The Easy Suite - Matlab code for the GPS newcomer" by Kai Borre. The Matlab code is available at the author's website: http://www.gps.auc.dk/~borre/easy
Download from here into your own matlab directory
matlab444.tgz

Google Earth Plus

Intended for personal use, Google Earth Plus is an optional, upgraded version of Google Earth available for $20. Why buy it? In addition to the basic features, Google Earth Plus includes:

GPS data import - read in tracks and waypoints from select GPS devices
o Note 1: Verified support for Magellan and Garmin devices only
o Note 2: Does not support export of tracks or waypoints to a GPS device
Higher resolution printing (greater than screen resolution).
Annotation – adds draw/sketch tools for richer annotations (can be shared as KML).
Data importer – read address points from .csv files.

To purchase Google Earth Plus, download Google Earth at http://earth.google.com/earth.html . Then run Google Earth and select "upgrade" from the "help" menu.

Excel or equivalent

For manipulating data tables in Comma-Separated Values (CSV) format.

ARC GIS (optional)

Student license $100 http://www.lic.wisc.edu/esri/StudentAV9.htm

Earth Bridge

It's a freeware (or donationware) program that listens to NMEA GPS data stream on a serial port and sends the data to a google earth .kml file along with a .net service which lets google earth know when the file is automatically updated.

Neal has tried it with the Garmin Etrex and another GPS receiver and it seems to work well with the free version of google earth. The earth bridge software can be found at http://mboffin.com/EarthBridge

GeoRobo

For tagging digital photos with GPS coordinates. No need for tricky connections between the receiver and the camera. Clever! http://www.robogeo.com/home/

GPSBabel

For translating data from one format to another.... http://www.gpsvisualizer.com/gpsbabel/

Automatic Point Positioning Service (APPS)

Estimate position for a single GPS station with sub-meter precision from a RINEX file containing (preferably dual-frequency) phase data from a geodetic - grade GPS receiver. The receiver may be moving.

http://apps.gdgps.net

Online Positioning User Service (OPUS) - Static

Estimate relative position for a fixed station with with respect to several stations of the CORS network in the US. Requires a RINEX file containing dual-frequency phase data from a geodetic - grade GPS receiver. Two different solutions are offered: Static (OPUS-S) and Rapid Static (OPUS-RS).

http://www.ngs.noaa.gov/OPUS

Hardware

Computer

If you own a laptop, please bring it to class on the meeting after the field mapping exercise.

Camera

If you own a digital camera with a USB cable, please bring it to class for the field mapping exercise.

GPS receivers

To be provided by the department of Geology and Geophysics in cooperation with Geological Engineering program. Click here for more information about the GPS facility.

Data Sets

UW - Madison Campus

KMZ file for Google Earth

Data files from Camp Randall for Problem Set 1

ALL data files from Camp Randall in compressed tar format

Driving from Berekeley campus to the SFO airport

KML file for Google Earth

Trimble 4600 LS

Neal was able to automate the Trimble nav file to RINEX obs and nav files. The converted 4600LS files are in a file called 4600Rinex.zip

We haven't looked to see if any of the data from the three receivers overlap.

Class Project: Presentations from Previous Years' Students

2008

Power Point Files

Golf Distances
Bus Stops
Lake Shore Preserve
Bike Racks
Patio Bars
Steam Tunnels

KML and KMZ Files for Google Earth

Zoo
Bus Stops
Bike Racks