Software modem for the Munin nano satellite

Abstract: At the Swedish Institute for Space Physics a very small satellite, a nano
satellite, is being constructed (1997-1998). The satellite, called Munin, is
built with standard components, but also carries state of the art scientific
instruments. A part of the project is to obtain a public outreach and to use
it as a educational tool, for these reason students are taking part in each
step of the construction and implementation process.

This thesis work describes the implementation of the ground stations
communication equipment. The reception mechanism consists of a modem, and a
PC controlling the modem. The modem’s main equipment is a digital signal
processor. All the logic for the modem is made in software. The modem
controller is made as an device driver under the Linux operating system on a
standard PC. The modem and the controller communicates over a standard RS232
interface.

The modem achieves acceptable bit error rates at realistic low field
strength levels for the signal to be able to receive the necessary amount of
data from the satellite.