Dynamic triple-difference method for single frequency GNSS structural monitoring

The shortcomings of both the single-epoch Method and the similar single-difference approach for GNSS deformation monitoring are analyzed in this paper, and the dynamic triple-difference (DTD) method, which uses single frequency carrier phase observations of two epochs tracking continuously by triple-difference, is proposed for dynamic deformation estimation of the structural monitoring with single frequency GNSS. The DTD method is characterized by non-ambiguity, smaller relative tropospheric error, the lower accuracy requirements for initial values of reference station and baseline vectors, and without applying the upper-bound restriction to the actual deformation. Thus, it can be anticipated that the DTD method has the advantages over existing methods due to focusing on the dynamic features of real-time structural monitoring. Finally, structural monitoring experiments of the third bridge of Nanjing Yangtze river are implemented to test the performance of the DTD method. It is shown that the natural frequency of the first order vertical bend of the third bridge and its corresponding signal are correctly derived from the dynamic deformation series using the DTD method with the help of both empirical mode decomposition (EMD) and Fourier spectrum analysis.