Pradinių duomenų klaidų įtakos GPS tinkluose analizė

Abstract

In this article the influence of initial data errors on the results of geodetic network adjustment is analized, whether a general adjustment is accomplished. For this purpose the coordinates of initial zero order stations and the chord coordinate differences of GPS first order networks were used. With regard to the initial zero order station errors the GPS first order network of Lithuania has been adjusted by using an elaborate program GETIS. Also the covariance influence of constituent chords into the adjusted coordinates of network stations was estimated. The covariance matrices that estimate separately an influence of initial data errors and measuring results have been obtained. By the use of GETIS program tool in various options the results of the adjustment were compared with the data obtained by use FILLNET program. The FILLNET program does not estimate the covariance influence of initial data and constituent chords on the adjusted coordinate values. Computational results have shown that the mean square errors caused by the influence of the initial data the adjusted station coordinates are approximately twice larger than the mean square errors of the same stations, caused by the measuring procedures. Therefore the zero order station coordinates are less accurate then the measuring results, eg the constituent chords. It was also determined that the covariance influence of constituent chords on the adjusted coordinates is quite important. It was found during the GPS first order networks analysis of the partial redundancy coefficients q for the adjusted constituent chords that their values are displaced in the interval of 0.37< ri< 0.93. It shows that the geometry of GPS first order network is optimal and the errors of measured quantities are under full control.