Date of Award

12-1990

Document Type

Thesis

Degree Name

Master of Science in Electrical Engineering

Department

Department of Electrical and Computer Engineering

First Advisor

Byron M. Welsh, Captain, USAF

Abstract

The primary goal of this research was to determine the feasibility of air-to-air optical communications systems using coherent detection in a turbulent environment. Secondary goals were to determine (1) the signal-to-noise ratio (SNR) degradation due to turbulence and (2) the effect of varying the wavelength (1.5, 830, 904 nm), altitude (5000-12500 m), path length (40-160 km) and aperture side length (1-15 cm) on the turbulence affected SNR. The research was conducted under the following assumptions: (1) ideal transmitter and receiver, (2) equally sized, uniformly weighted, square transmitter and receiver apertures, (3) ideal tracking by the receiver, and (4) zero losses due to beam steering, beam spreading and scintillation. It was shown that the SNR efficiency (defined as the ratio of the turbulence affected SNR to the non-turbulence affected SNR) ranged from 0.16 to 67.2 percent. The 67.2 percent efficiency was achieved for a wavelength of 904 nm, path length of 40 km, altitude of 5000 m and aperture side length of 1 cm.

AFIT Designator

AFIT-GE-ENG-90D-55

DTIC Accession Number

ADA230681

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