Design of a Telecommand and Telemetry System for use on Board a Nanosatellite

The telecommand and telemetry (TM/TC) system comprises a TM/TC circuit and a commercial off the shelf (COTS) VHF Transceiver. The main functions of the TM/TC circuit are the telecommand decoding and the telemetry formatting. The need for a compact TM/TC system, on board a Cubesat-Class Nanosatellite, poses a challenge for designing a small and light system. This paper describes the hardware and software solution achieved to design a compact TM/TC Circuit, which is based on the fixed point Digital Signal Processor (DSP) and includes AX.25 firmware and GMSK modem. Due to the environment in space and the constraints of the Cubesat concept, different measures have to be taken when the system is designed.