Dynamic Tripledifference Method for Single Frequency GPS Deformation Monitoring

Abstract:

The shortcomings of both the singleepoch method and the similar singledifference approach for GPS deformation monitoring are analyzed,and then 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 GPS.The DTD method is characterized by its nonambiguity resolution,lower accuracy requirements for initial values of reference station and baseline vectors,and unnecessary upperbound restriction to the actual deformation.Thus,the DTD method is expected to be superior to the existing methods for its dynamic features of realtime structural monitoring.Finally,structural vibration monitoring method is applied to the third bridge of Nanjing Yangtze River.Deformation by DTD method is consistent with that by singleepoch method in about 5 mm root mean square error.Moreover,with the empirical mode decomposition (EMD) and Fourier spectrum analysis,the spectrum of the bridge dynamic deformation derived from the proposed method exhibits a dominant peak at 0.25 Hz,which coincides with that obtained from finite element computation.

Key words:GPS; deformation monitoring; dynamic tripledifference(DTD) method; empirical mode decomposition(EMD); bridge