| 摘要 |
5 Optical communications system (10) and method for transmission of payload data (PD) from a low earth orbit satellite (20) to an optical ground terminal (30), the low earth orbit satellite (20) being connectable with the optical ground terminal (30) via an optical downlink channel (DL), and the optical ground terminal (30) being connectable with the low earth orbit satellite (20) 10 via an uplink channel (UC); wherein said uplink channel (UC) is an acquisition and tracking beacon channel by means of a ground beacon (GB) controlled by a point-acquisition-track subsystem (PAT), the ground beacon (GB) comprising a wide angle beam (W) for acquisition and a guidance beam (G) for tracking; and wherein the ground beacon (GB) for the uplink channel (UC) 15 is a pulse position modulated PPM channel. Fig. 1 10.10.2012/zg CS-0072P-AU w Fig. 1 |
