Preliminary Verification of the Optical Data Channel for COMPASSO

Kurzfassung

This thesis presents the preparatory work for the verification of the OSCAR data channel in the COMPASSO mission, conducted at the DLR. The objective was to start a verification plan for the receiver Field-Programmable Gate Array (FPGA), using MATLAB simulations and preliminary waveform emulation. The first part focused on generating and emulating the signal. Test frames were produced in MATLAB, uploaded to a waveform generator, and transmitted at 75 Mbit/s with Manchester encoding. Oscilloscope measurements confirmed the expected behaviour, with the dominant spectral component observed at 37.5 MHz, as predicted by the coding scheme. This validated the consistency between software-generated and hardware-emulated signals. The second part investigated receiver performance under controlled degradations, including Additive White Gaussian Noise (AWGN), Doppler shift, and bit flipping. Under AWGN conditions, the receiver exhibited clear optimal thresholds minimizing frame-related errors. The optimal threshold was found around 50 at 0 db, at 5 dB it shifted to 57 and at 10 dB it reached 62.5 with improved Frame Error Rate (FER) and Bit Error Rate (BER) increasing the Signalto-Noise Ratio (SNR), as expected. Additional tests with Doppler and combined Doppler+bit flipping produced similar trends, though the simulated impact of Doppler was weaker than theoretically expected. Nevertheless, the results confirmed the robustness of the receiver and the central role of threshold optimization. Overall, the work validated the signal emulation process, provided quantitative performance estimates, and delivered a structured verification plan. While real hardware tests are expected to show stronger degradations, the methodology and results presented here establish a reliable baseline for the upcoming testing campaign and the continued development of the COMPASSO optical data channel.