Prof. Shlomi Arnon

Decrease in signal to noise ratio and maximum bit rate, as well as increase in error probability in optical digital communication are caused by particulate light scatter in the atmosphere and in space. Two effects on propagation of laser pulses are described: (1) spatial widening of transmitted beam and (2) attenuation of pulse radiant power. Based on these results a model for reliability of digital optical communication in a particulate scattering environment is presented. Examples for practical communication systems are given. An adaptive method to improve and in some cases to make possible communication is suggested. Comparison and analysis of two models of communication systems for the particulate scattering channel are presented: (1) transmitter with high bit rate and receiver with avalanche photodiode and (2) transmitter with variable bit rate and a new model for an adaptive circuit in the receiver. An improvement of more than seven orders of magnitude in error probability under certain conditions is possible with the new adaptive system model.