24-09-2010, 03:20 PM
[attachment=4264]
presented by:
SUBIN.K.M
S7 ECE
ROLL NO: 01- 651
ABSTRACT
Laser communications offer a viable alternative to RF communications for intersatellite links and other applications where high-performance links are necessity. High data rate, small antenna size, narrow beam divergence, and a narrow field of view are characteristics of laser communication that offer a number of potential advantages for system design.
INTRODUCTION
Lasers have been considered for space communications since their realization in 1960. However, it was soon recognized that, although the laser had potential for the transfer of data at extremely high rates, specific advancements were needed in component performance and systems engineering, particularly for space-qualified hardware. Advances in system architecture, data formatting, and component technology over the past three decades have made laser communications in space not only a viable but also a attractive approach to intersatellite link applications. The high data rate and large information throughput available with laser communications are many times greater than in radio frequency (RF) systems. The small antenna size requires only a small increase in the weight and volume of host vehicle. In addition, this feature substantially reduces blockage of fields of view of the most desirable areas on satellites. The smaller antennas, with diameters typically less than 30cm, create less momentum disturbance to any sensitive satellite sensors. Fewer onboard consumables are required over the long lifetime because there is less disturbance to the satellite compared with larger and heavier RF systems. The narrow beam divergence of affords interference-free and secure operation.