Sensivity and accuracy analysis of different environmental and temporal measurements of the GPS values forming a basis for geographic information systems problems encountered, and determination of solutions

In this study, effects of multipath (reflection) on the spot positions of F(Forward) model, which is one of the errors encountered in Global PositioningSystem (GPS) measurements is researched. Network ITRF-96 has been formed of 1Turkish National Basic GPS Net (TUTGA), and 2 C3-degree triangulation pointswith a test point nearby the test area that would form a net together with them. Indetermination of the position of the test point; such a point where is close to the testarea that would look towards the sky widely and not be affected by reflection in thetest environment as far as possible has been considered. Geometrical structure of thenet has been designed in such a manner that would form obtuse-angled and shortedges (S<4 km); in other words, reliability of the net has been provided. In scope ofthe study, static measurements have been performed for 4 days and 45 minutesbetween 15.08.2012 and 18.08.2012. Reference measurement has been carried out ina non-reflexive environment, and these measurements have been regarded as thecontrol measurement. The control (reference) measurements obtained have beencompared with the measurements performed by signal-reflection geometries usinggalvanized sheets. Measurements have been carried out for 1 day in a non-reflectiveenvironment, 1 day in an environment of 4.8m × 4.5m = 21.6m2 plane of reflection, 1day in an environment of 4.8m × 9m = 43.2m2 plane of reflection, and 1 day in anenvironment of 4.8m × 13.5m = 64.8m2 plane of reflection formed.As a result of the study, it has been observed that X, Y and Z coordinates hadbeen loaded a 1 cm error in the solution independent from ionosphere, and a 0.1 cmerror in the automatic solution.Keywords: GPS, GNSS, GIS