Navigation Error Sensitivities for Communicating Between Fixed or Mobile Earth Stations and Satellites

Abstract

The task of communicating with a satellite from a fixed or moving station on or near the earth is becoming one that must be accomplished in an increasing number of applications. It is frequently necessary in these applications to point an antenna at the satellite, and to know the range and/or range-rate along the line-of-sight connecting station and satellite, within some allowable tolerance, in order to lock on and communicate successfully. Errors in the navigation variables of the station, that is, its three-dimensional position and velocity, and in the knowledge of position and velocity of the satellite, contribute to errors in “lockon” variables, i.e., antenna-positioning, range, and range-rate. This paper summarizes the formulas that allow the errors in lockon variables to be calculated, given the errors in satellite and station navigation variables. The error sensitivities, that is, the partial derivatives of the errors in lockon variables as functions of errors in navigation variables, are presented in tabular form.