This page provides some information about a communications payload (CP) designed by UniSA for the SUSat cubesat of the QB50 constellation.
This payload started in late 2013 at the ITR in UniSA. Here is information of some early stages of the project, including testing on a high altitude balloon. This material has been copied from the old ITR web site, so the formatting is not ideal, but it gives an idea of the project.
Here is a brief summary of the final SUSat CP. Launch of the QB50 cubesats was delayed until May 2017.
Here is a summary of the current SUSat status.
An interesting aspect of this cubesat CP design is the channel coding scheme. Channel coding is used on the downlink, which is more challenging in cubesats that the uplink where lots of transmit power is available. We are using a rate 4/5 Repeat-Accumulate code that allows very simple encoding (in space) on the MSP microController. A later version of this code is used in this project.
Link Budget Applet for Sat Comms
A simple link budget utility was developed for International Space University (ISU) workshops. This software was written as a Java applet several years ago. It allows link budgets to be calculated and provides some example parameters. Recent operating systems are wary of Java applets, but you can still use this software with an appletviewer or by setting specific permissions. The software is no longer available on the UniSA web site, but a copy is available here. This zip file includes a short tutorial explaining EIRP, G/T, link margins etc, plus some example link budgets, mainly for satellite comms