ADAPTIVE BANDWIDTH FOR SATELLITE OPTICAL COMMUNICATION

Satellites in free space suffer from periods of high displacement ampl itude vibrations. Most of the vibration is caused by satellite interna l subsystems (such as thruster firing or solar array drive mechanism) and controlled by the satellite computer. To utilise the advantages of optical communication in space, very narrow divergence transmitted be ams are used. The high-amplitude vibrations of the transmitter satelli te cause a decrease in received signal power in the receiver satellite due to mispointing of the transmitted beam. In the paper, the authors derive a model of a communication system that adapts the communicatio n system parameters to changes in received signal caused by changes in vibration amplitude. The purpose of this model is to keep the bit err or rate (BER) low and constant by adapting the system bandwidth and th e receiver parameters to the vibration amplitude. This model is useful for communication systems with two or more priorities of real time - for example, telephone calls and electronic mail. This means that, whe n the bandwidth shrinks, electronic mail messages may be delayed but t he phone calls can continue. Comparison and analysis of the performanc e of practical standard and adaptive models of communication systems f or variable vibration amplitude are presented.