Johns Hopkins University

Patrick A Stadter

William S Devereux

Mark S Asher

Eric A Olsen

A method of correcting ionospheric delays induced in received signals by space systems is disclosed. The method takes advantage of received GPS signals and received crosslink signals among spacecraft to estimate the effect of ionospheric delays and correct for such delays in the computation of the range estimation between spacecraft. The method generates and initial estimate of the ionospheric delay by tracking pseudorandom codes on both GPS and crosslink signals at known frequencies to correct an initial relative range vector. Using the corrected range vector generated from the use of code, the method subsequently estimates a more precise correction by considering the carrier phase error as induced by ionospheric delay. This includes estimate the integer ambiguities on both the GPS signals and the crosslink signals iteratively and subsequently estimating a more precise ionospheric delay correction with is applied to the relative position vector using the carrier phase measurements. The method is also applicable to non-navigation applications including measuring dynamic ionospheric structure and variability over a wide range of scale sizes, thereby greatly improving operational models of navigation and communications, and improving interdependent models of atmospheric, ionospheric, magnetospheric, and space weather physics and prediction.

Method for using GPS and crosslink signals to correct ionospheric errors in space navigation solutions

An integrated navigation and communication system that enables distributed spacecraft system operations. The system is a modular, extensible system that supports science operations among multiple, distributed spacecraft by implementing the essential functions of navigation, communication and control. Distributed spacecraft systems, also called formation flying systems, extend the capabilities of single-spacecraft missions by providing a platform for complex sensing tasks, including multipoint observation, co-observation, and distributed apertures. To accomplish these tasks, the system enables spacecrafts within a distributed spacecraft system to communicate science and coordination information, to determine relative position, velocity and time for command and control operations, and to operate in a coordinated manner to achieve common mission goals.

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Mt. Airy, MD, United States of America

Patrick A Stadter