Adaptive Radio Astronomy – 1. Correction of Phase Delay and Polarization Plane Rotation in the Ionosphere Using GPS Sounding Data and Ionospheric Modeling

Abstract

To correctly interpret radio astronomical data it is necessary to take into account possible distortions of these signals in the Earth ionosphere. We have developed the method and software for calculation of the ionosphere rotation measure (RM) and dispersion measure (DM). We used the ionosphere model IRI-2001, magnetic field model IGRF-10 and values of ionosphere total electron content as deduced from dual-frequency GPS receiver measurements. With the obtained DM and RM values, these of phase delay, polarization twisting and Faraday amplitude modulationwere then calculated. We made calculations for different levels of geomagnetic activity and for different angular position of radio sources as well. Our main idea is to use signals of navigation satellites (GPS, GLONASS, GALILEO) as a testing signal from the “reference” source located at minimal angle distance from the studied one. Our project clears the way to development of the methods and systems of the adaptive radio astronomy, adaptive to non-uniform and non-stationary ionosphere, by analogy with the known systems of adaptive optics intended for adaptation of optical telescopes to varying conditions of optically non-uniform and non-stationary troposphere.