Abstract

An interactive computer program has been written to aid in the definition of technologies required for optical intersatellite communication links. Input parameters are varied and the bit error rate (BER) is calculated for the link. The parameters are broken down into the following categories: laser transmitter parameters, laser pointing parameters, satellite tracking parameters, modulator characteristics, and detector performance characteristics. The model simplifies the analysis of interplay between these independently controllable parameters, allowing a rapid numerical evaluation of a configuration of interest. The model consists of six primary modules each containing between one and six subroutines. The function of the modules can briefly be described as follows:

(1) INIT initializes input parameters and admits systematic variation of a given parameter of interest;

(2) TRANSMIT calculates the power incident on the detector taking into account the transmitter power, free-space divergence loss, pointing loss, tracking loss, transmission loss through optical components, and modulation loss;

(3) BACKGROUND determines the effects of optical background from sources such as stars, the moon, the earth, and the sun;

(4) SIGNAL/NOISE calculates the detector signal-to-noise ratio (SNR) with dark current, thermal noise, shot noise, electronic noise, and optical background present;

(5) BIT ERROR calculates BER as a function of SNR for a given modulation format;

(6) DISPLAY tabulates and plots the data.

© 1986 Optical Society of America