Research On The Precise Point Positioning Based On The CORS Network

Precise Point Positioning(PPP), is an absolute positioning method using precise ephemeris and precise clock products to get high-precision position in a single station. Precision in three directions(NEU) of static position can achieve centimeter level.Different from differential positioning, there are several main difficulties in PPP to overcome.Firstly, the errors from the satellites.singal propagation and the receiver should be considered during the data processing. As PPP cannot eliminate spatial correlational errors the way differential positioning model use, how to correct all kinds of errors become the key problem of PPP. Secondly, data preprocessing which includes cycle slip detection, gross error elimination, clock slip detection, and set of elevation mask angle is more complicated than diiterentiai positioning without double-difference or triple-difference phase observation. This limits the methods that data preprocessing can take.Thirdly, PPP cannot fix the integer ambiguity except that it is combined with reference stations net. In general. PPP result in float solution, degrading the positioning accuracy and convergent rate compared with differential positioning model.In this study, we adopt the dual-frequency ionospheric elimination model and took all kinds of errors into consideration which may decrease precision of PPP. Through mathematical modeling, the orbit deviation of satellites, clock errors of satellites, phase center deviation of satellites and receivers, wind up delays of satellites, second-order delays, troposphere delays, earth tide delays, relativistic effect delays, and earth rotatiom delays can be basically eliminated.As to data preprocessing, this paper employ the classic TurboEdit method capable of detecting cycle slip and removing gross errors.After all those processes, setting coordinates of station, wet component of zenith tropospheric delay, receiver clock and every integer ambiguity of observable satellites as unknown parameters, we can get results through Kalman Filter model.In the experiment, we apply observations of different stations to verify precision of PPP. Finally, this study aims at developing a visual GPS data processing software with high positioning precision.Besides, this software have multiple functions and traits, including automatic and simple operation, complete interface, I/O function, auto update function and so...