Investigation of the Effects of Pointing Errors on Optical Intersatellite Links Using Real Orbital Data

Abstract

In this paper, performances of optical communication links between satellites that are located in Low Earth Orbit (LEO) and Geosynchronous Earth Orbit (GEO) are analyzed in three different scenarios under effect of pointing errors. The scenarios are conducted in intra orbit (LEO-LEO and GEO-GEO) and inter orbit (LEO-GEO). TLE (Two Line Element) data of the real satellites are used as initial values to simulate the movements of the satellites. Satellite orbits and orbital perturbations are approximated by finding the state vectors in geocentric equatorial frame using Gauss variational equations for the satellites. Gaussian channel model is used to simulate the channel conditions, since communications links in space applications generally do not suffer from multipath. Based on the simulations, it is observed that pointing requirements affects the Bit Error Rate (BER) crucially. Results of the simulations show that inter-orbit communication link suffers most from the pointing errors. Calculations are done in MATLAB and Simulink.