Track of the May 28 Balloon taken from APRS data received by the chase vehicle.

To ensure we found the balloon we had multiple, redundant, independent tracking systems.


APRS was our primary tracking system.

The APRS (GPS) system transmits information directly to our laptops. This information includes altitude, speed, direction, and location. The APRS will send this information every 30 seconds. The APRS GPS system runs on its own batteries. There is an antenna connected to thAPRS Data - 6/1/12 launche APRS which runs on a separate 12v battery pack.

APRS - web site

APRS Data - 6/1/12 launch


The SPOT satellite tracker acted as a backup, only to be used if the APRS failed to work.

The SPOT system uses satellite signals to send information to the web. It sends a signal every 10 minutes. This is a long period between signals but it is also very dependable. This system also only gives a location reading. With the satellite location reading it makes for a very dependable tracking system.


We had a cell phone with Instamapper tracking software to act as a backup tracking device.

The Cell phone like the APRS system collects data including the following: altitude, speed, direction, and location. It also sends a data feed every 30 seconds. The cell phone sends this information to a cellphone tower which then sends the information to us. The only disadvantage of the cell phone is when it reaches altitudes to high it is out of cell service.

Internet TrackingEdit

All three of our tracking systems are routed onto the Internet. To make it easier to access this data tiny url short cuts for each website have been created.




The APRS tracker is configured with the callsign KF7DXI-11 and is received by amateur stations and can be viewed on the Internet through any APRS website or client, such as the website.

The SPOT tracker data is available on the Internet at the SPOT Shared Page.

The cellular tracker relies on the free software and service Instamapper. The data is online at the Instamapper shared page.

We found that the SPOT website was hard to use with mobile phones. So an attempt to have a better user interface to all three tracking systems during the chase we created some scripts to gateway the SPOT and cellular tracking data onto APRS with the callsigns KF7DXI-12 and KF7DXI-13 respectively. Therefore all three tracking methods can be viewed simultaneously at

During ChaseEdit

All of our tracking methods data is routed onto the Internet making tracking very easy when online. In the vehicle during the chase we couldn't rely on a good Internet connection. We could receive our main method of tracking, APRS, independent of the Internet by using a radio in the vehicle connected to laptop running software (Soundmodem and Xastir ) to decode the position sent by the APRS transmitter and place it on a map.

During the May, 16, 2011 launch we received packets directly from the balloon for the entire launch.