Search

Aiming at the situation of errors in observation data and coefficient matric in GPS Height anomaly, a robust total least squares (RTLS) is proposed with a IGGIII weight function based on standardized residuals. The method only takes the parts containing deviation in coefficient matrix into consideration. Taking the 80 groups GPS observation of benchmark as an example, the feasibility and accuracy of TRLS is analyzed compared with two kinds of experiment including 43 groups of data for fitting (4 groups of data with gross error) and 37 groups of data for testing. If the data have no robust, the result of RTLS is equal with robust LS. If the data have robust, the result of RTLS is better than robust LS. The experiment shows that the method of RTLS is the best choice when fitting GPS height anomaly. [ABSTRACT FROM AUTHOR]

In order to study the temporal and spatial variation characteristics of the regional ionosphere, a regional ionosphere model was established based on the spherical harmonic function model and the GPS dual-frequency observation data of the European continuously operating reference station network.The reliability and stability of the differential CODE bias of the GPS satellites are analyzed, and the precision analysis and vertical total electron content of the ionosphere in the European region are carried out. The results showed that the average value of the DCB and CODE deviations of GPS satellites in the selected time period is less than 0.15 ns, and the root mean square is less than 0.2 ns.The root mean square of the difference between the calculated result and the vertical total electron content of CODE is less than 1.53 TECU.Applying the ionosphere in the European region to precise point positioning, the 327 d residual values are less than 0.3 cm in the E direction, less than 0.42 cm in the N direction, and less than 0.6 cm in the U direction, indicating that the addition of the ionosphere has the most obvious improvement in the U direction. In the 3D direction, the European region ionosphere is better than the CODE ionosphere, and the residual value is improved by 0.32 cm. [ABSTRACT FROM AUTHOR]

According to the problem of complex data processing caused by the correlation between stations and satellites in the double-difference network RTK(real-time kinematic), an algorithm of BDS un-difference network RTK with triple-frequency is proposed. Firstly, the integer linear relationship among extra-widelane, wide-lane and triple-frequency integer ambiguity is used to determine double-difference integer ambiguity between BDS network RTK reference stations. Then, according to the composition relationship between double-difference and un-difference integer ambiguity, un-difference integer ambiguity between reference stations is quickly determined at single epoch. On this basis, a high-precision region error correction model of BDS un-difference is established to realize the error correction and integer ambiguity fixing of use. This algorithm is tested by the measured triple-frequency data of BDS CORS(continuously operating reference stations) network. The results indicate that the algorithm of un-difference network RTK with triple-frequency can effectively overcome the correlation between station and satellite which is brought by the double-difference network RTK and make the operating type of the network RTK more flexible. [ABSTRACT FROM AUTHOR]

Ambiguity fixing is the key to GNSS high-precision dynamic positioning. In order to analyze the performance of a GPS/BDS combined system on ambiguity search efficiency and the success rate of ambiguity fixing on a short baseline, this paper proposes an ambiguity search region correlation method based on the square roots of the eigenvalues of the variance/covariance matrix of ambiguity. This method compares and analyzes the ambiguity search region in a single system GPS,a single system BDS and combined GPS/BDS system, respectively. Experimental results show that the GPS and BDS combination influences the variance/covariance matrix of each single system, and reduces the search region of each single system. Furthermore, the statistical results show that the combined GPS/BDS system can improve the success rate of ambiguity fixing and the ambiguity search efficiency significantly within single- and dual- frequency observations. [ABSTRACT FROM AUTHOR]