Applicability Assessment of the GNSS Ionospheric Delay Refinement Technique in Single-Frequency Measurements

Abstract

Additional results are presented to assess the applicability of a methodology for refining the ionospheric delay of global navigation satellite systems (GNSS) signals in single-frequency measurements for a network of remote receivers using data obtained at a reference receiver located at the center of the network. The ionospheric delay is calculated using the IRI global ionospheric model, adjusted for the current situation using the critical frequency values obtained during measurements at a vertical sounding (VS) station. For two chains of selected directions of sub-ionospheric points of GNSS signal trajectories in the vicinity of the reference receiver – longitudinal and latitudinal – the spatial radius of the effective ionospheric delay refinement is estimated under specific conditions. The feasibility of developing a methodology by using critical frequency data, obtained by measuring the difference in ionospheric signal delays from two navigation satellites (NS) with subionospheric trajectory points located close to a reference receiver, to correct the ionospheric model for the current situation is considered. Modeling was conducted to determine the critical frequency for two sub-ionospheric GNSS signal trajectory points located near a reference receiver located in Moscow. When compared with critical frequency measurement data from the Moscow VS station, the average absolute error for all time points in the determinations was approximately 0.6 MHz, with a relative error of 0.06.