Jay McMahon, University of Colorado Boulder
Keywords: precise orbit determination, solar radiation pressure, geolocation
Abstract:
Geolocation of unknown transmitters used for jamming satellite signals has a long history. The state-of-the-art method for precisely locating such transmitters is to construct time- and frequency-difference-of-arrival (TDOA and FDOA, respectively) measurements using the jammed spacecraft and a neighboring spacecraft, both of which are typically in geosynchronous orbit. When well calibrated and implemented, this process can provide a significant amount of very precise TDOA and FDOA measurements to carry out the geolocation process.
However, in order for the geolocation to be done accurately, the satellite ephemerides must also be well known over the data arc. The TDOA and FDOA measurements also provide a wealth of information that can be used to improve these ephemerides through precise orbit determination. At geostationary altitudes, the largest source of error for orbit determination is the non-gravitational forces, in particular solar radiation pressure. Therefore, in order to improve the orbits of the spacecraft in question, and thus improve the geolocation solution, improvements in solar radiation pressure estimation are desired.
In this work, we demonstrate improvements in precise orbit determination or geosynchronous spacecraft by estimating coefficients from the Fourier SRP model using TDOA and FDOA measurements. In particular, we present results using operational data for three investigations: first, we investigate which coefficients can and should be estimated; second, we demonstrate the accuracy of the force model by using pass-through residuals over predicted arcs; and third we discuss methods for a priori coefficient construction to enable successful coefficient estimation.
Date of Conference: September 11-14, 2018
Track: Poster