Design of a Telemetry Link for Direct Communication between Femtosatellites in Low Earth Orbit and Earth Ground Stations

摘要

Designs for small satellites with mass 10-100 grams are the next iteration in reducing spacecraft size and mass. Although femtosatellite concepts hold the potential for novel mission designs and reduced launch and manufacturing costs, there are significant challenges to designing within such a tiny form factor. Due to spatial and power constraints, it has been proposed that femtosatellites would have to relay data through a nearby larger "mother" spacecraft. We propose a communication system designed to enable direct communication between femtosatellites in LEO and ground stations. Using software defined radio applications running on an embedded system, a custom signal design with forward error correction will enable this direct downlink, thereby keeping mission costs and complexity to a minimum. We describe how to use a low cost, open source single board computer to prototype the femtosatellite's communication system.