GPS tinklų išlyginimo skirtingais programų paketais kokybės analizė

Abstract

In this article the quality of the second order Lithuanian GPS network adjustment is considered by three software tool packages: Fillnet, Turbonet and Geosecma. In the analysis, the modified Student criterion defining the influence of large errors on the adjusted values of composite chords was employed. The essential difference between the Fillnet software tool and Turbonet software tool is that in Fillnet software tool the chord composite covariance is ignored, while in Turbonet software tool this fact is taken in account. On the basis of Student statistics there is shown that the covariance influence is sufficiently essential. Moreover, by ignoring the covariance the incorrect accuracy was obtained estimating the adjusted values, which is relatively better. Then the real confidence intervals for the adjusted coordinate depatures are much larger then those shown by the software tools that ignore the covariance factor. Finally, using the Student statistics the influence of the systematic errors on the adjusted values was analysed too.