Communication

The CubeSTAR communication system is composed of two parts: the space segment onboard the satellite and the ground segment (ground station). The purpose of the system is to operate the satellite from the ground and transmit collected data from the satellite back to the ground station.

Telemetry, Tracking and Command System
The communication space segment also known as the Telemetry, Tracking and Command (TT&C) system is used to communicate with the ground station. The system is tasked to:
-     Transmit telemetry from the satellite to the ground station
-     Receive commands sent from the ground station
-     Transmit a tracking signal to the ground station 

The TT&C system operates in the UHF amateur satellite band (435-438MHz) and was designed after Global Educational Network for Satellite Operations (GENSO) compability recommendations. The radio link features:
- 9600 baud
- Gaussian Frequency Shift Keying (GFSK) modulation scheme
- AX.25 data packet protocol
- Frequency: 437.465MHz (coordinated by IARU)

The system will also transmitt a periodic tracking signal. The signal is morse coded, transmitting 24 Words Per Minute (WPM) on a continious wave (CW), containing some basic information on ID and satellite health. 

 
Ground Station
The CubeSTAR ground station has been constructed, using the hardware components recommended by GENSO. The antenna rig is comprised of four UHF Yagi antennas and two rotors which make it possible to change the elevation and azimuth angles. The antenna rig is situated on the roof of the faculty building.
The ICOM-910H radio is used to receive and transmit RF signals.
The hardware (i.e. rotor and radio) is controlled through the Ham Radio Deluxe (HRD) software package. The program allows for automatic tracking of the satellite and compensation of Doppler shift in the radio signal.
A custom LabView application is employed to perform de-/modulation and AX.25 de-/capsulation as well as provide a GUI to the ground station operator.