Noise analysis based on FSO-SIM signals in plasma sheaths

This study analyzed the noise of FSO-SIM signals in a plasma sheath. The primary focus was on the impact of refractive index fluctuations caused by plasma turbulence on signal transmission quality during high-speed movement of spacecraft in near-Earth space. By establishing a refractive index fluctuation model, the study explored the effects of background noise and thermal noise in photodetectors on bit error rate (BER). The results indicated that thermal noise has the greatest impact on the system, and a solution was proposed to suppress thermal noise by adjusting the load impedance, thereby enhancing system stability. Finally, the bit error rate performance of BPSK and DPSK subcarrier amplitude modulation signals in plasma turbulence was compared, concluding that DPSK outperforms BPSK under most conditions. The research findings provide a theoretical basis for optical communication in plasma sheath turbulence.