Investigation of MSK and FSK modulation schemes for single channel communications system using DSP techniques on-board low Earth orbit microsatellite

The constraints and requirements placed on modulation schemes by LEO microsatellites communications systems are summarized and followed by the introduction of an in-orbit research tool, the Digital Signal Processing communications Experiment payload (DSPE) on-board the PoSAT-1 microsatellite. The preliminary in-orbit communications experiments using PoSAT-1 DSPE are described, including optimizing a CPFSK modem and the in-orbit evaluation of a novel DSP-implemented MSK coherent demodulator and decoder. The purpose of these communications experiments is to maximize data throughput during the limited communication time while satellites transits the user´s horizon