Long-Baseline Differential GPS based Relative Navigation for Spacecraft with Crosslink Ranging Measurements

摘要

This paper derives fundamental relative navigation solutionsrnfor distributed spacecraft systems exhibiting longbaselinern(e.g., 100's-1000's kin) separation and deployingrnon-board Crosslink Transceiver (CLT) subsystems [1].rnThe Crosslink Transceiver provides an integrated relativernnavigation and communication system and the performancernanalysis is based upon the current system underrndevelopment for the National Aeronautics and SpacernAdministration (NASA) for several formation flying programs.rnThe described research contributes to three challengesrnrelated to relative navigation performance of longbaselinernsolutions: the model derivation for a hybridrnDGPS and crosslink ranging approach, the impact ofrnthe ionosphere on the crosslink ranging measurements forrnnear Earth orbiting formations, and the consequences ofrnthe crosslink signal on the DGPS integer ambiguity problem.rnSimulations were developed to characterize the impact ofrnthe ionosphere and to investigate the integer ambiguityrnresolution problem. A model for the crosslink ionosphericrnrange delay was developed and the results are discussed.rnFinally, additional issues related to the implementationrnof the transceiver subsystem are presented. In particular,rnit is shown that the transceiver subsystem must "selftrack"rnin order to obtain highly accurate (cm-level) measurements.