No abstract

No abstract

In this paper, which represents a continuation of the previous author's work, an inconstancy of GPS residual error ANOVA estimates and their variances are presented. For the purpose of the analysis, fixed solutions for all of the three coordinates, e (eastwards), n (northwards) and u (upwards), obtained by using ionosphere-free (L0) linear combination of double-difference phase observations in the processing of GPS data, were employed. The aim of the research was to consider the behaviour of variances of GPS residual error ANOVA estimates in time because there has not been any paper dealing with that issue so far. Herein, it turned out a seasonal pattern in related time series was present. In addition, it was concluded there was a difference in ANOVA estimate extreme values obtained when one considered daily data subsets compared to those obtained in the approach considering monthly data of the fixed solutions. GPS data collected at ending stations of a baseline of 40 km in length within a four-year period, involving the lowest and increased solar activity, were used in calculations.V prispevku predstavljamo spremeljivost ANOVA-varianc časovnih vrst GPS-koordinat. Za namene analize smo določili koordinate na podlagi dvojnih faznih razlik opazovanj GPS z uporabo ionosferskega vpliva proste linearne kombinacije opazovanj (L0), ob faznih nedoločenostih, določenih v množici naravnih števil. Namen raziskave je bil ugotoviti značilnosti časovno spremenljivega obnašanja ANOVA-varianc časovne vrste koordinat in izkazalo se je, da je v časovnih vrstah koordinat prisoten sezonski vpliv. V primerjavi dnevnih in mesečnih koordinat so bile za dnevno določitev koordinat zaznane večje razlike med vrednostmi ANOVA-varianc. Pri izračunih smo uporabili podatke štirilenih opazovanj GPS za bazni vektor dolžine 40 kilometrov, pri čemer so bila opazovanja izvedena v obdobju nizke in tudi povečane Sončeve aktivnosti.

In this paper, a new two-stage approach, involving an integral treatement of all quasi-random effects limiting the accuracy of relative GPS positioning and the method of moments to obtain final variance components regarding the effects of short-term (“far-field”) multipath (factor b), joint action of long-term (“near-field”) multipath and receiver antenna phase center offset and variations (factor a1), as well as joint action of tropospheric and ionospheric refraction (factor a2), is presented. In the study, GPS data collected on five baselines were used. Variance components of the quasirandom effects were obtained for the three relative GPS coordinates (e, n and u) using individually monthly datsets including daytime- and those including nighttime-wise ambiguity-fixed baseline solutions. The related results show that statistically significant inequality exists when comparing corresponding variances obtained for daytime and nighttime periods. It turned out that the following standard deviation estimates intervals are present (by the coordinates e, n and u, respectively): (a) daytime period: 3.3–6.9, 4.6–9.0 and 9.1–20.3 mm (factor b); 1.5–4.7, 1.9–7.0 and 3.4–21.9 mm (factor 1a ); 0.0116– 0.3282, 0.0103–0.2365 and 0.1222–0.7818 mm/km (factor a2); (b) nighttime period: 3.2–4.9, 4.7–7.3 and 8.4–15.4 mm (factor b); 0.8–3.8, 2.1–5.0 and 3.1–15.8 mm (factor a1); 0.0118–0.2734, 0.0097–0.2289 and 0.0752–0.6315 mm/km (factor a2).

No abstract