Date : 11/06/2026
Hour: 16:00
Student Name & ID: Doğukan Yavuz 255105112
Supervisor: Asst. Prof. AHMAD SALMANOGHLI KHIAVI
Topic: Investigation of Phase Noise Degradation in Satellite Downconverter LOs and Its Impact on High-Data-Rate Modem Performance
Link or Room: C-322
Abstract:
In modern satellite communication systems, particularly in S and X-band earth stations where earth observation and telemetry data are downloaded at ultra-high data rates, the spectral purity of the receiver front-end is of paramount importance. To process high-frequency RF signals at the modem architecture, they must be translated down to the L-band intermediate frequency (IF) using a mixer driven by a Local Oscillator (LO). The fundamental bottleneck determining the quality of this downconversion process is the phase noise of the LO, which is stabilized by a Phase-Locked Loop (PLL) synthesizer. This seminar study provides a comprehensive analysis of PLL architectures and examines the optimization procedures of loop filter parameters (loop bandwidth and phase margin) regarding system stability and noise shaping. Furthermore, the destructive effects of LO-induced phase noise on the signal quality of high-speed digitally modulated (QPSK and 8PSK) satellite waveforms are evaluated. Through the power-law spectral noise model and linear phase-domain transfer functions, the coupling relationships between phase noise spectral density, integrated phase jitter, Error Vector Magnitude (EVM), and Bit Error Rate (BER) degradation are investigated.