F.N. Zakharov - Ph.D. (Eng.), Research Scientist, Department Radio Engineering Systems, Tomsk State University of Control Systems and Radioelectronics E-mail: ZakharovFN@main.tusur.ru S.G. Gosenchenko - Ph.D. (Phys.-Math.), Senior Research Scientist, Department Radio Engineering Systems, Tomsk State University of Control Systems and Radioelectronics E-mail: rwplab@tusur.ru M.V. Krutikov - Head of Laboratory, Department Radio Engineering Systems, Tomsk State University of Control Systems and Radioelectronics E-mail: rwplab@tusur.ru

In the article [1] the model of the troposphere refractive index vertical profile was considered. Estimates of navigation signals zenith delays were obtained using these profiles. At lower elevations, where the navigation spacecraft (NSC) is above the horizon at an angle α, the delay is increased by lengthening the path in the troposphere and is determined by the mapping function. Additionally, random error due to spatial inhomogeneity of the troposphere refractive index is appeared. As the characteristics of the random spatial distribution of refractive index uses the structure function, which is a variation of the mean square of the fluctuation components of the module increments when moving from one point to another. Air sounding results were used to construct the structure function. These results were obtained in the region of the Sea of Okhotsk on board the research vessel «Akademik Shirshov» and upper-air sounding stations on the island of Urup and in the cities of Yuzhno-Kurilsk, Poronaisk and Yuzhno-Sakhalinsk. The following assumptions were used at processing air sounding and carrying out calculations. It is assumed that the statistical properties of the field of refraction index does not depend on the direction at all heights within the entire study area. Features of influence of the continents on the statistical properties of the refractive index field are not taken into account. Due to the irregular height measurements in sounding for computing study altitudes used linear interpolation sections profile of the refractive index between the nearest points to the desired height. It is believed that the spatial structure of the refractive index field is the same for the same period in different days. This allows a spatial averaging of the differences in term of different days. The structure functions constructed on each of the heights of 1, 2, 3, 4, and 5 km to determine the structure of the refractive index height profile. Constructed in such a way the dependence of the structure function of the distance was approximated by an exponential function. Using the results the dependence of the fluctuation error in the layer of the troposphere to a height 7 km from the elevation was constructed. The maximum value of the mean square error of the troposphere determination of the distance due to horizontal large-scale inhomogeneities can be determined using the obtained relationship. The error is 35 m at an elevation angle of zero degrees at a distance of 345 km. It was found that the fluctuation error is on the order of 15-20% of the average troposphere delay of the signal. The obtained results allow us to estimate the accuracy of the compensation limit tropospheric delay of radio navigation signals.

 

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