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ŠUMARSKI LIST 7-8/2016 str. 44     <-- 44 -->        PDF

estimated by PPP. The accuracy of satellite ephemerides data and clock products used in the technique, and error models considered in the computations refer strongly to the point positions to be estimated. Considering seperately the error models shown in Table 3 are especially significant factors for improving the accuracy of point positioning in PPP.
Static GPS Surveying and Data Analysis – Statično ispitivanje GPS-om i analiza podataka
In this study, the established ground control points so called TP01 and TP02 have been observed repeatedly in static GPS surveying mode for 3 days and per day with 3-hours observation duration. Surveys have been conducted on consecutive days at 16th, 17th, 18th July 2012 (GPS Day of year=Doy: 198-199-200). During the surveys, dual frequency Thaless Z-max geodetic grade GPS receivers and Ashtech (ASH701008.01B NONE) geodetic grade antennas have been used. For all surveys, the record interval is 1 second and satellite cut-off angle is taken 10 degree. The heights of GPS antennas were measured in millimeter accuracy. The software and services listed in Table 4 have been used for post-processing and analyzing the static GPS data observed. The commercial software Topcon Tools v8.2 have been preferred to manually process of the data. The automatic processing has been done by web based online services namely AUSPOS, OPUS, CSRS-PPP, APPS and GAPS. The results have been provided in observation epoch and International Terrestrial Reference Frame 2008 (ITRF2008) datum. Final satellite ephemerides products provided by IGS have been used for both manual and automatic processing except APPS service. APPS service uses final satellite ephemerides products provided by JPL.
PALA and KCEK permanent stations included in İSKİ-CORS network operated in Istanbul have been taken as reference stations for the solutions with commercial software Topcon Tools v8.2. The PALA and KCEK stations are approximately 10 km far away from the study area. In the evaluation process, IGS final ephemerides products have been considered (URL-9).
From the analyzes that have been obtained from processing the static GPS data observed around the forest environment, with different software, the cartesian coordinates and standard deviations of them obtained for two test stations are represented in Table 5 and Table 6.