Center for Mapping

Introduction

Analysis was done by testing high-end dual frequency GPS receivers (Trimble 4000SSE and SSI, Trimble 4700, Topcon/JPS Legacy, Leica 9500 and 399, and Ashtech Z-12) in static, benign conditions on the short and zero baselines, and subsequently, in kinematic scenario. The data collected during the static tests was used to quantify the receiver noise characteristics in order to analyse differences between the quality of GPS measurements provided by different geodetic-grade hardware. The level of the receiver noise was used to estimate the weight assigned to the one-way GPS observables in the least squares adjustment process. Uniform weights were used to all the phase (or range) observables, assuming no correlation at the one-way (or single difference) measurement level. However, some recent studies have shown that for the most demanding applications (deformation or crustal motion monitoring, etc.), where the highest precision is required, this model might is not adequate, and a more involved stochastic modeling is essential to monitoring data integrity, and the estimation of the position quality resulting from the least squares adjustment. Consequently, studying the receiver noise characteristics as well as temporal correlation and non-correlation way lead to the improved variance-covariance model for GPS observables.

Problem Overview| Receiver Performance Considerations| Static Tests| Kinematic Tests