Distributed Ground Station System for AAUSAT4.


9. semester Network Performance Analysis and Optimization (Netsec)

AAUSAT4 is the next student cubesat from AAU - Department of Electronic Systems.

The launch is scheduled to autumn 2014.

Our three first cubesats has all been solely operated from our ground station in Aalborg. This means that we have less than 1 hour of contact every 24 hours and furthermore no backup or redundancy.

For that reason it is obvious we would like to have a real distributed ground station system.

We are now in August 2013 establishing a ground station at Thule Greenland, but we still need the real distributed solution where we can add ground stations around the world.

See Pyxis - the first version.

The Problem in short

The most important factor when running experiments up in space is to get the huge amount of data down. AAUSAT3 - launched 25. February 2013 - has during the first 5 month delivered less than 50 MBytes of data. So it is obvious that optimization of down link protocols has very high importance.

AAUSAT3 uses forward error protocols which survive many bit errors but also more than double package size. AAUSAT-II did use AX.25 which is efficient bit a single bit error is a show stopper.

The project

The goal is to design the best downlink protocol for cubesats seen ever:

  • Analysis and modelling of channel
    • varying channel due to fading, tumbling, range,...
  • Analysis of protocols for the different link quality
    • Ax.25, FEC,...
  • Design and implementation of a space link based on AAUSAT3,pyxis, own ideas
    • including dynamic optimization

Based on AAUSAT3 we honestly think that downlink capacity can be at least doubled compared to AAUSAT3.


implement it on AAUSAT4


Jens Dalsgaard Nielsen, Jesper A. Larsen or Rasmus L Olsen(jdn,jal,rlo AT es.aau.dk)

  • Analyse existing ground-space communication used for AAUSAT3
  • Model space link according to 7. layer model or equivalent
  • Design of a distributed space link
  • Design of parallel data receive protocol which can reduce bit error rates by voting
  • handover
  • more to come
  • simulate it
  • implement it :-)

The project is very open in the sense that you as part of the AAUSAT4 team will define the goal and project contents in detail.

contact Jens Dalsgaard Nielsen or Jesper A. Larsen (jdn,jal AT es.aau.dk)