Hybrid modulation as beacon replacement in CubeSat picosatellites

At present a CW beacon with Morse code or OOK modulation is still commonly used in picosatellites (especially in CubeSats) for signaling that picosatellite is currently rising above the horizon and for limited telemetry transmission about picosatellite functionality. This transmission with limited EIRP could be replaced by proposing group of hybrid modulations DM-FSK/DQPSK and M-FSK/DQPSK with better performances. These modulations offer a better spectral and energy efficiency in comparison to OOK and also offer the possibilities of continual received signal quality evaluation. This is useful for modulation adaptation or switching in the main picosatellite radio transmission subsystem. The main advantages of conventional CW beacon (such as simple signal processing and good human audibility in the noisy channel) stay with using of proposed hybrid modulations, presented in this paper.