The Donald P. Wilson '33 and Edna M. Wilson

Freshman Seminar 142

Where's Waldo? The Science and Application of GPS

Spring, 2007


None yet!

Course Instructor: Ed Groth, Jadwin 264, x8-4361,

Office Hours: Most afternoons - give a call before walking across campus! Almost surely Wednesday afternoons, 2:00-4:00 pm.

Seminar: Monday, 1:30-4:20 pm, T5 Blair Hall (Buyers).


In this course, we will study the science, technology, and applications of the Global Positioning System. What are the physical principles behind the system? What technologies are required for the system to function? What is a handheld GPS receiver doing when it tells you where you are? What does it mean to know where you are?

Among the many topics we will cover are the overall plan of the GPS system, the satellite constellation, the ground coordination of the system, and GPS receivers. We will learn about the orbits of both the Earth itself and satellites, the shape of the Earth and the effects of the ionosphere and other atmospheric variables. How we map the Earth and our position on the planetócoordinate systems, projections, map reading and plotting GPS positions will be important topics. We will explore questions of precision and error such as military vs. civilian accuracy, differential GPS, and relativistic effects. And we will investigate GPS connections and applications to other new technologies such as wireless communication (cell phones, wireless internet). Some of our topics will be determined by student interest.

To satisfy the laboratory requirement, we will take data with hand held GPS receivers, and upload them to computers for graphing and analysis. We will experimentally determine the errors and the error distribution of GPS positions in the Princeton area and we'll find out how some of these errors can be overcome by differential GPS. We'll learn about maps and projections by hiking and bicycling in the area and planning and documenting our routes on topographic maps. Students may also participate in the activity known as geo-caching: a technology based treasure hunt.

This seminar is intended for both science and non-science majors. Students should be comfortable with math at the level of algebra, trigonometry, and geometry.

Readings will be chosen from numerous articles on the web, Scientific American, and articles in the popular press. Readings will range from introductory to advanced, and the more technical parts will be discussed in the seminar. Lab reports will be due after each project. There will be a 10- to 15-page term paper which will also form the basis of a presentation to the seminar.


Here is the tentative scheme for determining grades in the course: The grades will be based on the paper and presentation (35%), projects (35%) and class participation (30%). Class attendence is required!


Here are some reference sites on the web: The first site is a collection of links to just about everything to do with GPS on the web. The second site also contains a list of links but is more academically oriented.

Software for reading the GPS receiver with your (windows) laptop: EasyGPS and GPS TrackMaker.

Software to use with a Mac running OS/X: Commercial ($50, but works well and supports both native USB and the Keyspan Serial to USB adapter), MacGPSPro. Free, but you need to also download and install expat and libusb (see the instructions). I couldn't get it to work with my Keyspan adapter, but it did read USB natively (with libusb). I couldn't get it to upload an almanac. GPSBabel+. Be sure to read the on-line documentation! Bottom line seems to be, if you have a Legend, Venture, or Vista C or Cx, you can use GPSBabel for most functions. If you have a basic eTrek, Summit, Legend, Venture or Vista (i.e. no C or Cx), you will need the Keyspan USB to serial adapter and this doesn't work with GPSBabel (at least I haven't been able to get it to work!). So you will need MacGPSPro or perhaps you can borrow a friend's PC!

Update 21-Feb-2007. For a Mac have a look at GPSMan.


Week Date Topics, Readings, Projects, Activities
1 5-Feb-2007 Overview of course and GPS system.
Suggested reading: A list of GPS Tutorials,
Global Positioning System Overview,
and any other of the introductions found on the references cited above.
Project: Waypoint Hunt.
2 12-Feb-2007 Some questions to help focus the discussion.
(Based on the same references as the first week.)
Reading for next week: same references but focus on the method of transmitting information, "spread spectrum techniques," and Doppler shift.
Project: GPS in Flat Land
3 19-Feb-2007 Some questions to help focus the discussion.
More than you wanted to know about the GPS data format.
Reading for next week: learn about maps, map projections, advantages and disadvantages of various projections. What is a topographic map? What do elevation contours mean?
Project: GPS and Maps.
4 26-Feb-2007 Some questions to help focus the discussion.
Reading for next week: learn about GPS errors.
Project: GPS Errors.
5 5-Mar-2007 Some questions to help focus the discussion.
Reading for next week: learn about differential GPS and WAAS.
6 12-Mar-2007 Some questions to help focus the discussion.
Paper Topics Due
Project: Geocaching.
  19-Mar-2007 Midterm Break
7 26-Mar-2007 Project: Differential_GPS.
8 2-Apr-2007 Discuss Differential GPS
Unfinished Topics
GPS and Relativity
9 9-Apr-2007 Presentations: Jeff, Jonathan, and Kevin
Presentations and Photos
10 16-Apr-2007 Presentations: Sudeep, Lincoln, Farrell, and Evan
Presentations and Photos
11 23-Apr-2007 Presentations: Zach, David, Bill, and Grayce
Presentations and Photos
Final Project: Treasure Hunt
12 30-Apr-2007 Team Treasure Hunt
Course Wrap Up
15-May-2007 Papers Due