Calculation of average acquisition probability for spiral–circular composite scanning in free space optical communication

This study investigates the acquisition probability calculation method for spiral–circular composite scanning (SCCS) in free space optical communication. The concepts of effective coverage area (ECA) and average acquisition probability (AAP) are proposed. Owing to the fast movement of the fine tracking system (FTS) of the transmitting terminal, the beam width of the transmitter is enlarged from the perspective of the receiving terminal, and the ECA is actually the enlarged area. Based on the concept of ECA, the SCCS can be considered as the traditional spiral scanning (TSS) with an enlarged beam. Then the AAP calculation method is presented to describe the acquisition probability by considering the field of uncertainty (FOU) and platform vibration simultaneously. Furthermore, the AAP builds up a connection between two existing concepts of acquisition probabilities and includes them as special cases. The effectiveness of the proposed method is validated by Monte Carlo simulations.