Development of algorithms and programs for estimation of electron content and radiotomographic restoration of the electron concentration field in the ionosphere based on radio signals of satellite systems

The processes of scattering, dispersion and absorption accompanying the propagation of an electromagnetic wave lead to the fact that the radio signal slows down and weakens when passing through electron clusters in the ionosphere. The article solves the problem of restoration of the electron concentration field based on ionospheric radiography. The derivation of analytical relationships for determining the total electron content (TEC) in the ionosphere based on radio signals of the global navigation satellite system (GNSS) at two frequencies is considered. The methods for calculating TEC both from direct satellite signals and cross-relaying based on a small-sized CubeSat retransmission satellite are considered. Analytical relationships are given and algorithms for estimating TEC calculated based on phase and pseudo-distance measurements are described. They are then used to construct computing tomography algorithms in order to estimate the structures of the restored electron density images. As a result, the proposed radio tomography algorithms use TEC data to synthesize two-dimensional images of the electron concentration field in the ionosphere which allows the estimation both of the structure and dynamics of the ionosphere.