Labs from Chicago, Fall 1993 :
The Packsat Project.

Dr. Jim Sweitzer
Labs written for the CARA Space Explorers, Fall 1993

This is meant to be handed out to the students.

Satellite Communications: The Packsat Project

(We will also do a session up at Yerkes Observatory after Christmas.)


Satellite communications are vital to the workings of our modern world. Many of your telephone calls and almost all of the TV you watch relies upon a satellite at some point to relay the communications you receive. In fact, satellite communications is probably the biggest benefit of all the money we have spent in the space age.

In this short course you are going to become an expert in understanding basically how satellites work and how they can be used for communications. In fact, with a lot of hard work and a little luck, we should be able to communicate directly with a Russian satellite.

We will also learn about two very advanced communications technologies. Packet communications is where the information is sent in digital bursts. This is how computers "talk" with one another. We will see first hand how this technology works and try to listen to satellites talking with one another using "packets" of information. Finally, we will learn how cellular telephone communications work and even investigate a new system of satellites that will be launched soon that is a big cellular system that covers the entire Earth. It's called Iridium.

Part of the reason in doing this class is so that you will be prepared for future work we will be doing with amateur radio and satellites. The Space Explorers program has an application into NASA to contact an upcoming Shuttle mission. You will be taking a ham radio class next year and this will be useful for that class. The college is about ready to purchase a radio that will allow us to communicate with satellites. We will also probably be experimenting with satellite communications at both the North and South Poles. Most of all, however, it is just an interesting way to learn some physics you will need later in high school and college.


You will be evaluated for your performance in this course. Your attendance is required at every session. If you can't attend you must bring a note the following week from a parent or OSP to excuse your absence. Even if you are unable to attend you will still be held responsible for doing the homework. I will give you a yellow folder to keep the handouts and work in for this class. You must bring this with you each time. If too many people start forgetting their yellow folders, then I will require you to bring it to class if you want to get credit for attending on that day.

You will team up with a couple of other students to do a project. Your team will be graded on the final project and a couple of the project milestones along the way. Your final score for the course will be figured using the following percentages: attendance = 20%, homework = 40%, and project = 40%.

Course Plan

Session	  Date         Topic
   1    October 27     Introduction, Circular Motion
   2    November 10    Kepler's First Law 
   3    November 17    What Keeps a Satellite Up?
   4    December 1     Satellite "Footprints"
   5    December 8     Keeping a Date with a Satellite
   6    December 15    Doppler Radio Waves
   7    December 27/28 Packet Radio
   8    January 19     Iridium System
   9    January 26     Project Seminar
Note that there are a couple of Wednesdays when we won't be meeting. We will also be going up to Yerkes Observatory after Christmas and will use some of that time to work on research projects. Note below that you will have some due dates in early January.


This class grade will be heavily weighted by projects that you and your team members do in the course of the quarter. I will divide you into teams during the first class. Below is a list of potential project subjects. Between the first session (today) and next week, you and your team should think about the projects you would most like to do. Rank them in order of your preferences. When you come in next week we will all decide together which group does which project.

All the projects are research projects. All members of a team will get the same grade for the groups performance. This is a real research collaboration! I will give you some references to get started next week. Your team will be expected to contact an outside expert. I will track these people down for you. The person listed as Advisor is the outside person you must contact. (TBD means To Be Determined.) Below are the project milestones (or due dates, if you like).

Each completed project must consist of three things:

  1. A term paper, of no less than 1,000 words. This should be done using one of the Macs at OSP and should be a Teach Text file. Pictures or illustrations are welcome and should be included in most of the projects.
  2. A transcript of an interview with your advisor concerning your topic. This too must be typed into one of the Macs at OSP and given to me as a Teach Text file.
  3. A 15 minute oral presentation to be delivered during the last class.
Here are the due dates for the various milestones of your project:

Packsat Projects

Project 1: Why use Satellites for Science?
Advisor: Simpson
Many space scientists use satellites and space probes to conduct their research. Why can't they just use telescopes? What are some of the most stunning discoveries that satellites have made since they were first used? Dr. Simpson is a pioneer in the business of using satellites. He's here at the University and just a nice person. Currently he is getting ready to launch a satellite to measure the dust and debris around the Earth.

Project 2: Russian Amateur Satellites
Advisor: TBD
In class we will use a Russian satellite as the one that we interact the most via the radios. It's called RS10/11. There are a couple of others, I think. This group is responsible for describing the details about these satellites, their history and how they work for us in writing and pictures. I am in the process of trying to contact a person from the Moscow Radio Club. He (or she) will be your advisor. You will contact them over the computer network called Internet.

Project 3: Packet Radio
Advisor: Jendraszkiewicz
Computers, whether it is over a wire or over phone lines or even with a satellite communicate to each other using "packets." This group will describe how packet radio communications work. We will experiment a little with this in class. When you receive your radio license next year, you will be doing lots of packet radio. The contact person here is Gerry Jendraszkiewicz. He is an engineer with the University and a top-notch amateur radio person who has helped us set up the station on campus.

Project 4: How Cellular Telephones Work
Advisor: Givens
Although cellular phones are really an Earth-based technology (for now at least), they involve a form of digital communications that are the wave of the future. This group will write a paper that describes how the cellular phone system works. Mr. Givens is a fascinating engineer at a local company called Tellabs. They write the computer programs to make cellular phones work.

Project 5: Motorola's Iridium Project
Advisor: TBD
By the time you are in college, Motorola will have phones that you can put in your pocket that will use satellites like a cellular phone system. They will enable you to make a call from anywhere on the Earth. This communications project is called Iridium. This research group will write a paper describing how Iridium will work. You should also brainstorm in your group to think of unusual ways such a global phone system will be useful. I will find an expert at Motorola who will be able to help answer questions and give you an interview.

Project 6: Packet Satellites
Advisor: Reeves
There is a type of satellite that is about the size of a personal computer and flies very fast in a very low orbit. In fact it is really just a computer with a radio attached to it. When it talks back and forth to computers on the ground it does so with packets. This research group will research these small satellites, describe them and tell how they are used. You might even get to use one. The advisor for this class is a teacher in California. He and his class, who use them all the time, will help you. Your connection with them will also be over the Internet, computer network.

Important Disclaimers and Caveats

Go back to the Chicago Fall 1993 Satellite home page.