Development of a versatile ground station for satellite communications

Abstract

The purpose of this project is to create a communication link from a Student Ground Station at the NOAA facility in Fox to the Cubesat Communication Platform (CCP) Cubesat . The Student Ground Station will send Commands (Uplink) and receive Telemetry (Downlink). The radio onboard of the CCP Cubesat is the GOMSpace AX100, which is a Commercial off the shelf system. The GOMSpace AX100 uses Cubesat Space Protocol and AX.25 standards for their packet structure. The GOMspace AX100 uses Frequency Shift Keying (FSK) for modulation. My project will use a Software Defined Radio (SDR) that was coded in Matlab to communicate with the GOMSpace AX100. For Uplink, I will receive bits from COSMOS and conform to Cubesat Space Protocol and AX.25 standards. After I have Cubesat Space Protocol and AX.25 encoded bits, I perform FSK modulation on the bits and send the voltages to the SDR. In Downlink, I will receive samples from the SDR and perform FSK demodulation. After I have bits from demodulation, I will perform AX.25 decoding, then Cubesat Space Protocol decoding. The payload is then extracted from the decoded bits, then the payload data is sent to COSMOS for interpretation. I was able to successfully send commands to the GOMSpace AX100 and I was able to decode Telemetry packets sent by the AX100, which means I was are able to establish a communication link to the AX100.