Correlators for Synthetic Apertures in Space

In this paper we analyze existing technology and simulate possible work flows to find the best hardware and data processing strategies for the position solving and correlation steps of space based radio arrays at various scales. Such arrays are composed of many free flying spacecraft, and accurate knowledge of their relative positions is necessary for proper data analysis. By using signals from existing Global Navigation Satellite System (GNSS) satellites, each individual spacecraft may record data that can be used to solve for precise orbit determination (POD) solutions to determine the relative propagation delays between each spacecraft pair. Any errors in the position are translated into phase error of the complex correlation data. The acceptable limits of error in position before harming the localization of the radio array are tested, using localization performance of SunRISE as a test case. This work help sets requirements for future space based arrays, particularly the quality of GNSS signal needed on each spacecraft as well as correlator capabilities. It is found that there are several feasible hardware and software combinations available today that could constitute a space based array, and recommendations are provided on which combinations would be well suited for various correlation strategies.