Simulation of Satellite Telemetry-Telecommand Coherent Transponder

Abstract

The Telemetry/Telecommand Transponder is the unit on board a satellite that maintains the communication link between the satellite and the control center on the Earth. The spacecraft includes service telecommunications Telemetry and Telecommand (TMTC) and On-Board Supervision (OBS) subsystem to provide telemetry, telecommand and ranging functions during all phases of the mission. The function of transponder, generally, is receiving the uplink signal modulated with telecommand and ranging tones, process it, and transmit the downlink signal (at different frequency) modulated with telemetry and ranging signal to the ground station. In this research, European Space Agency's recommendations and standard have followed to calculate the coherent transponder parameters. The coherent transponder and the related communication functions have been simulated using MATLAB Simulink software version 6.5. The computer simulation was necessary to show the performance of such functional block under the influence of many parameters like Doppler shift, input signal level variation, and damping factor variation.