Research On Evaluation Method Of Measurement Uncertainty Of GPS Project

After the measurement uncertainty was proposed, some scholars made a research on the uncertainty evaluation of GPS receiver and hand-held GPS, which has received some achievements.But researches on comprehensive evaluation method for uncertainty of Engineering GPS measurement data are still scarce.In order to make the construction of engineering project fully realize the reliability of the measurement results so as to ensure the quality of the project construction, the paper presented a new method to evaluate the uncertainty of measurement by combining the GUM method with the characteristics of GPS data, which based on theoretical research and practical test. Studying from the theory, the equivalent distance deviation as well as each error source in the process of the Engineering GPS single point positioning and relative position has been analyzed aiming at the observation method,measuring environment, working procedure, instrument and equipment, and data processing. The error probability distribution was studied with the method of statistics, which determined the probability distribution characteristics of GPS single point positioning and relative positioning error,and it points out that the single point positioning error of the project GPS is not completely following the normal distribution. A mathematical model for evaluating the uncertainty of Engineering GPS measurement was proposed and established. Based on GUM method and combined with the probability distribution characteristics of single point positioning and relative positioning error of Engineering GPS, two kinds of suitable uncertainty evaluation schemes were put forward, and the evaluation of expanded uncertainty was completed; After the evaluation scheme was tested and analyzed through existing engineering GPS control network measured data, the scheme was proved to be feasible.