Abstract
Abstract A simple and relatively fast method (C-SART) is presented for tomographic reconstruction of the electron density distribution in the ionosphere using smooth fields. Since it does not use matrix algebra, it can be implemented in a low-level programming language, which speeds up applications significantly. Compared with traditional simultaneous algebraic reconstruction, this method facilitates both estimation of instrumental offsets and consideration of physical principles (expressed in the form of finite differences). Testing using a 2D scenario and an artificial data set showed that C-SART can be used for radio tomographic reconstruction of the electron density distribution in the ionosphere using data collected by global navigation satellite system ground receivers and low Earth orbiting satellites. Its convergence speed is significantly higher than that of classical SART, but it needs to be speeded up by a factor of 100 or more to enable it to be used for (near) real-time 3D tomographic reconstruction of the ionosphere.
Highlights
Computerized tomography (CT), developed in the 1960s, continues to play an important role in the field of medical imaging
We have extended simultaneous algebraic reconstruction technique (SART), which does not depend on matrix operations, to enable it to carry out tomographic inversions accurately using simple physical relationships
4.2.2 Known Differential code biases (DCBs) and initialization with background model To demonstrate how SART and CONSTRAINED SIMULTANEOUS ALGEBRAIC RECONSTRUCTION TECHNIQUE (C-SART) perform when all DCBs are known and the models are initialized with a background ionosphere model, IRI2007 electron density profiles were computed for an epoch of 1 month preceding the one used in the previous section
Summary
Computerized tomography (CT), developed in the 1960s, continues to play an important role in the field of medical imaging. The simultaneous algebraic reconstruction technique (SART), a refinement of ART developed by Andersen and Kak (1984) that solves multiple equations simultaneously, is better suited for real-time applications. It is used in radiological and medical applications, seismic investigations, material science, among others. Wen et al (2007b) presented an improved algebraic reconstruction technique (IART) based on classical ART It computes the relaxation parameter at each iteration step adaptively. One has to place the same condition on the satellite DCBs. bi = 0 (i being the number of artificial observations) has to be applied in order to set up the zero-sum condition when using SART
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