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Ge X.,Tongji University | Wu J.,Tongji University | Wu J.,Key Laboratory of Modern Engineering Surveying
Cehui Xuebao/Acta Geodaetica et Cartographica Sinica | Year: 2012

Total least squares method is a deregularizing procedure, so the ill-posed problems will be more serious. That means errors in the data are more likely to affect the total least squares solution than the least squares solution. It is proposed using generalized regularization to solve ill-posed problems in total least squares, so as to improve stability of the results. Finally, numerical experiments are carried out to demonstrate the performance and efficiency of the generalized regularization method which have significant advantages in solving ill-posed problems.


Wang C.,Tongji University | Wang J.,Tongji University | Wang J.,Key Laboratory of Modern Engineering Surveying | He L.,Tongji University
Wuhan Daxue Xuebao (Xinxi Kexue Ban)/Geomatics and Information Science of Wuhan University | Year: 2012

A real time cycle slip detection method is proposed based on Jarque-Bera test for testing the normality of slip parameter in epoch window, which constructed by bi-differences of pseudo range and carrier phase observations. Real time cycle slip detection tests are analyzed with GPS static observation data and on-board GPS dynamic data. The results indicate that the algorithm can detect outliers in real time, and provide the base of data quality controlling for real time precision orbit determination and positioning.


Ge X.,Tongji University | Wu J.,Tongji University | Wu J.,Key Laboratory of Modern Engineering Surveying
Wuhan Daxue Xuebao (Xinxi Kexue Ban)/Geomatics and Information Science of Wuhan University | Year: 2012

According to the traditional approach of three-dimensional datum transformation and classic least-squares (LS) theory, the weight constraint total LS (WCTLS) and mixed LS are introduced. A more reasonable model and the corresponding iterative algorithm are given. The example results show that the new model is more reasonable indeed and the more accurate parameters of datum transformation can be obtained with suitable weight assigned.


Ge X.,Tongji University | Wu J.,Tongji University | Wu J.,Key Laboratory of Modern Engineering Surveying
Cehui Xuebao/Acta Geodaetica et Cartographica Sinica | Year: 2013

Based on the objective measurement accuracy, we attempt to use the residuals of measurements in both design matrix and observation value to replace the positive constant. A few numerical experiments are carried out to demonstrate the performance and efficiency of the new method.


Xie Y.,Tongji University | Xie Y.,Chinese Academy of Sciences | Chen J.,Chinese Academy of Sciences | Wu J.,Tongji University | And 2 more authors.
Wuhan Daxue Xuebao (Xinxi Kexue Ban)/Geomatics and Information Science of Wuhan University | Year: 2014

Based on different constraints, double-frequency measurement data from 11 GPS stations in the vicinity of China and 230 global GPS stations were used to calculate vertical ionosphere electron content(VTEC), the DCB of GPS satellites, and corresponding receivers based on the spherical harmonic function model. The results show that the VTEC and the combination DCB of GPS satellite and receiver were not affected by constraints. The DCB precision of the combination obtained is less than 2 ns comparing with CODE, and the correction rate of VTEC relative to CODE can reach up to 90 percent. We also predict spherical harmonic coefficients using the AR model; the correction rate of VTEC based on the prediction coefficients can reach to 80 percent; thus fixing the sum of the satellite DCBs is better than fixing a single satellite DCB.

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