Analytic pointing error evaluation on nano-satellite laser communication system

This study uses comprehensive pointing control analysis to calculate laser pointing errors for nano-satellite laser communication systems. This methodology especially enables the performance evaluation of the pointing system during the satellite pointing budget design phase. The analysis consists of a two-stage pointing approach: a body pointing stage of a satellite and a fine pointing stage within the optical payload. By simplifying each pointing stage to a single-axis model, we derive their error transfer functions, which are converted into power spectral density (PSD). The PSD of the two stages are combined using linear interpolation due to the difference in their sampling frequencies. This process yields the final laser pointing error PSD. Our method is validated against Monte-Carlo simulation results and control experiments of the fine pointing stage. The simulation and the experimental results maintained correspondence with the modeled power spectral density. These comparisons can suggest the proposed approach can predict the pointing performance of the system. Based on these results, a method to determine controller gains is introduced, aiming to minimize final pointing errors.