1. TCP/IP Communications over Iridium Satellite Modems
Nick Spera
Faculty Mentor: Dr. Gary Gear
NASA Mentor: Larry Freudinger
Saturday, April 19, 2008
Embry-Riddle Aeronautical University
Electrical Engineering
NASA Dryden

2. Motivation Long-range science missions
Retrieve data from polar sensors
Artic ice flows, climate change, etc.

3. Problem Line-of-sight is not a possibility
No access to military satellites
Must work with Linux

4. Solution Iridium network works globally and is readily available
However, Iridium is limited to 2400bps
Multiple channels are aggregated to increase data rate - MultiLink

5. Diagram Physical Iridium Physical Satellites Logical Linux Linux
MultiLink
Linux PC
Linux PC
Logical
MultiLink
Base
Station
Sensor
Data

6. MultiLink Viable solution, readily available and cost-effective
Complications:
TEQL
Dropped links
TCP/IP issues unique to our environment
MPPP
Robustness of the configuration

7. Success and Conclusion
After months of research and vigorous trial and error, a workable solution was still out of reach
Embry-Riddle students suggested an alternate approach using different software (MPPP instead of TEQL)
This shift in direction brought immediate results and allowed NASA to begin finalizing and polishing the system