Author
Abstract
In this research, we analyze the effects of vibrations and the atmospheric on
turbulence for a broadband laser satellite down link (BLSDL). The use of optical
radiation as a carrier between satellites and in satellite-to-ground links enables
transmission using very narrow beam divergence angles. Due to the narrow beam
divergence angle and the large distance between the satellite and the ground
station or any object the pointing is a complicated process. Further complication
results from vibration of the pointing system caused by fundamental mezchanisms
: tracking noise created by the electro-optic tracker and vibrations caused by
internal satellite mechanical mechanisms. Additionally an in homogeneity in the
temperature and pressure of the atmosphere leads to variations of the refractive
index along the transmission path. These variations of refractive index as well as
introducing other external noise, pointing vibrations, can cause fluctuations in the
intensity and the phase of the received signal leading to an increase in link error
probability. In this research, we develop a bit error probability (BEP) model that
takes into account both pointing vibrations and turbulence-induced high amplitude
fluctuations (i.e., signal intensity fading) in a regime in which the receiver
aperture antenna (Do) is smaller than the turbulence coherence diameter (do), the
results indicate that the satellite broad band laser down link with the receiver can
achieve a BEP of 10-9 and data rate of lGbps with normalized pointing vibration of
and turbulence with
After reducing these limitation of laser satellites and compensates
relatively most atmospheric error probabilities due to atmospheric turbaulences
(BEPS) or variation of refractive index by using for ward feeding under fine
tracking which designed to decrease the residual jitter influencies or by using
directional laser beam or introducing feeding forward compensation method and
adaptive techniques to reduce the effect of system vibrations [12].
Keywords
)
