On the contribution of horizontal gradients of the ionosphere into the errors of GNSS range-finding

Unlike the customary treatment of the GNSS positioning errors, based on the expansion of the phase advance in terms of the inverse powers of the frequency of operation, an alternative treatment of the contribution of the ionospheric errors in the accuracy of the GNSS positioning is suggested, which is based on the perturbation theory in small horizontal gradients of the electron density of the ionosphere. The results of calculations according to this technique are presented and compared with the previous representation of the phase advance in terms of the series in the inverse powers of the frequency of operation. The advantages of the new technique are highlighted.