Overview of the content

This lesson includes an overview and discussion of the tracking system: Iridium, OCCAMS and termination. This lesson includes an overview of Global Navigation Satellite Systems, including GPS. 

Coming soon: information on the vent and the SPOT tracker.

Learning objectives

After completing this lesson, students will be able to:

  • Explain how balloons are tracked through the Iridium network and tracking websites
  • Understand Iridium OCCAMS, Termination and Vent


Iridium Control System

Iridium Control System (AHAC poster)

  • The Iridium system is a modem that connects our custom PCB, called an Occams board, to the Iridium satellite network so we can communicate to our payloads via our ground station. This system connects to our other payloads on our string using the XBee radio frequency modules. These modules are also used as microcontrollers for other systems on our flights.


Iridium (TM) Satellite Tracker MODEL 9602-LP

The tracking Iridium Modem and XBEE3 Control payload collects the local GPS data from the GPS satellites and provides the connection to the Iridium Satellites that in turn connect through the Iridium Ground Stations for distribution over the internet to the Montana State University database.


9602-LP Product Information (from NAL Research - external site)

9602-LP User Guide (from NAL Research - external site)

9602-LP Quick Start Guide (from NAL Research - external site)



The OCCAMS unit communicates with the redundant cutdown system. There is a PCB mounted 2.4 Ghz antenna on the XBEE3 short range radio that is required to communicate with the OCCAMS unit. Care should be taken to make sure this is not near metal or other transmitters.

OCCAMS: Optimized Command and Control Aerial Management System

  • ​​Documentation for OCCAMS v9 or later and software versions 1-3 or later. Notes and troubleshooting will apply to previous versions but use your discretion. Differences in board design can be seen in each respective design section.​ Last update Dec. 15, 2022


schematic drawing



High Altitude Student Platform (HASP) 2021 Final Report

  • Montana Space Grant Consortium-Montana State University Student Team Lance Nichols, Tim Uhlenbruck, Josh Phillips, Andy Kirby Authors Lance Nichols, Tim Uhlenbruck Faculty Advisors Randal Larimer, PE, and Dr. Michael Walach Abstract There is growing interest within the university and light payload balloon community to utilize zero pressure or solar heated balloons to provide extended or long duration flight capability.



Coming soon

SPOT Tracker

Coming soon


Global Navigation Satellite Systems (GNSS) -- this presentation will help you become familiar with the design and operation of Global Navigation Satellite Systems (GNSS) especially the Global Positioning System (GPS)



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