This paper presents an experimental and theoretical framework to determine parameters of an atmospheric optical communication link using multiple-forward-scattered (MFS) radiation. The study itself simulates in a laboratory environment the various physical factors that are encountered in the actual atmospheric channel. Parameters that affect signal-to-noise fluctuation at the receiver channel, such as multiple scattering of the laser beam off particles in clouds and the atmosphere, sky background, and the effects of direct illumination by the solar flux, are evaluated. Using a GaAlAs laser diode (λ = 0.8486 μm) as a source, the MFS optical channel parameters are evaluated. The system margin using a pulse position modulation format for this laboratory-simulation scattering medium with a quartz-halogen background condition was determined as a function of field of view for various data rates and background noise. For a specific optical depth of the scattering medium, values of the data rates are determined for which communications can be maintained in the presence of direct background noise radiance whereas a negative margin for higher data rates will result in an excessive error rate. Acquisition and high rates transfer between aircraft in low-visibility atmosphere seem to be feasible providing a relatively covert system with high immunity to jamming.
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