Fully-polarized high-orbit SAR (synthetic aperture radar)-based ionized layer time-varying TEC (total electron content) measurement method

Abstract

The present invention discloses a fully-polarized high-orbit SAR (synthetic aperture radar)-based ionized layer time-varying TEC (total electron content) measurement method. The method includes the following steps of: step 1, azimuth synthetic aperture point number calculation; step 2, azimuth data zero filling; step 3, azimuth Fourier transformation; step 4, azimuth signal decompression to obtainequivalent azimuth echo spectrum signals; step 5, azimuth inverse Fourier transformation; step 6, Faraday rotation angle estimation; and step 7, time-varying TEC acquisition during synthetic aperturetime. By means of the above seven steps, fully-polarized high-orbit SAR signals are utilized to complete the precise measurement of the time-varying TEC during the synthetic aperture time. The methodof the invention has high time-varying TEC measurement accuracy. Since a Faraday rotation angle model and a TEC inversion model are adopted, the method has higher measurement accuracy compared with atraditional measurement method.

Description

technical field [0001] The invention relates to an ionospheric time-varying total electron quantity (TEC) measurement method based on a fully polarized high-orbit synthetic aperture radar (SAR), and belongs to the technical field of signal processing. Background technique [0002] In recent years, with the development of science and technology and social progress, satellite communication, satellite navigation and space-based radar systems have been widely used in various aspects of military and civilian use, and have become an indispensable tool for human life, which makes the world including the ionosphere Space environment monitoring and technical support are becoming more and more important and urgent. At the same time, BIOMASS, NISAR and other satellite programs will detect the global atmospheric environment including the ionosphere, and the detection data will provide important help for geospatial weather science and meteorological support for space information systems,...

AI Technical Summary

Problems solved by technology

However, since all the existing studies involved are spaceborne fully polarized SAR systems in low and medium orbits, the satellites fly faster and the synthetic aperture time is shorter, so they can only focus on the ionospheric TEC distribution (i.e., space-variable TEC) for detection, but it is impossible to achieve accurate detection of time-varying TEC in a fixed area

[0004] At the same time, the current research on high-orbit SAR only stays on the imaging error compensation caused by the ionosphere, and most of them use the phase gradient self-focusing processing method to estimate the error phase caused by the time-varying TEC in the ionosphere.

However, since this method does not use a fixed error model in the processing process, it only estimates the error phase based on the phase gradient change between pixels, thus completely losing the absolute phase error caused by the ionospheric time-varying TEC, so it is impossible to achieve accurate detection of time-varying TEC

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