Observability in Space-Based Data Processing

This short paper is intended to present a preliminary analysis of observability and signal processing associated with a satellite-based tracking system. Various satellite orbits and their effect on observability of moving and stationary objects on, or relatively near, the earth's surface are presented. Obviously, there is a tradeoff between area surveyed and sampling interval as a function of satellite altitude and number of satellites in a constellation, e.g., for complete coverage by a single satellite, the minimum viewed swath width on the earth, considering earth rotation and oblateness, for a circular-orbit satellite at 150 nm (nautical mile) altitude is 675 nm. The geometric swath width (maximum possible surveyed swath on the earth) is 1995 nm. The overlap determines the maximum number of times an earth-based object can be viewed by a single satellite during successive orbits.