Bandwidth maximization for satellite laser communication

Free space optical communication between satellites networked together can make possible high speed communication between different places on Earth. T he basic free space optical communication network includes at least two sat ellites. In order to communicate between them, the transmitter satellite mu st track the beacon of the receiver satellite and point the information opt ical beam in its direction. The pointing systems for laser satellite commun ication suffer during tracking from vibration due to electronic noise, back ground radiation from interstellar objects such as Sun, Moon, Earth, and St ars in the tracking field of view, and mechanical impact from satellite int ernal and external sources. Due to vibrations the receiver receives less po wer. This effect limits the system bandwidth for given bit error rate (BER) . In this research we derive an algorithm to maximize the communication sys tem bandwidth using the transmitter telescope gain as a free variable based on the vibration statistics model and the system parameters. Our model mak es it possible to adapt the bandwidth and transmitter gain to change of vib ration amplitude. We also. present an example of a practical satellite netw ork which includes a direct detection receiver with an optical amplifier. A bandwidth improvement of three orders of magnitude is achieved in this exa mple for certain conditions, as compared with an unoptimized system.