Design and Construction of a Communication Module for Nano-Satellites

Abstract

The communication module of a satellite is the main component used to build and operate a communication link between the satellite and the ground station. The communication module mainly comprises a transmitter and a receiver. The command uplink, the telemetry and mission data downlink, and the continuous wave (CW) beacon are the three main components of a communication module.In this work, communication module hardware is implemented on a 10 cm x 10 cm PCB (standard PCB size for nano-satellites) using a LoRa module and an ATmega328P-PU microcontroller. The operation of the hardware was tested on a ground-based platform. The graphical user interface of the ground station was designed using Visual Studio 2019. Uplink commands and telemetry and mission data are handled using this interface. The uplink command is transmitted at 433 MHz with a 62.5 kHz bandwidth. The data rate is approximately 4690 bps. The uplink command is modulated with the LoRa <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">™</sup> modulation technique with 20 dBm of output power. Telemetry and mission data downlink link specifications are the same as the specifications of the command uplink. CW Beacon transmits at 433 MHz with a 20 wpm data rate. The CW Beacon transmits 10 dBm of power and it is modulated with the CW Morse code. Telemetry and mission data downlink performance test was successfully done for a 100 m distance between the designed transmitter and the receiver. We believe that this can be extended to distances over 100 km by improving the antenna gain at the ground station as the antenna gain can easily be increased to a value greater than 15 dBi.