Study On Time And Frequency Transfer Using GPS Carrier Phase

The objective of this dissertation is to cover the time and frequency transfer using GPS carrier phase based on Ashtech Z12T receiver. The research provide an introduction to the GPSCPTT principle with an emphasis on, Ashtech receiver calibration and other error sources correction, cycle slip detecting and repairing and ambiguity resolution algorithm, et al. Based on these researches, the GPSCPTT between UTC(k) and UTC(j) is primarily realized, and the time transfer software package of GPSCPTT is developed. The major contents include:A detailed principle of GPSCPTT is developed. The principle of the GPS carrier phase measurement is simulated using the Matlab Simulink and the carrier phase measurement is achieved by real observation data.In order to improve the GPSCPTT precise, several new mitigation techniques for several errors correction are proposed, mainly include: the application of the IGS observation data to the troposphere correction, the comparison of correctional precise between dual frequency P code and dual carrier measurement, the results indicate that the later has higher precise than the former whenτ< 5 ~ 6d, the correction of the solid tide effect on the antenna coordinate perturbation, the application of the IGS precise ephemeredes and clock products to the GPSCPTT, the Ashtech Z12T receiver calibration.The cycle slip detection by combining polynomial fit and dual frequency ionosphere residual which can detect the small cycle slips equals to 0.5 cycles is also investigated, meanwhile, a method based on wavelet transform to detect and repair cycle slip is discussed.The classical LAMBDA method which can resolve both the coordinate of the receiver and the ambiguity resolution is improved. And the improved method only can reckon the ambiguity resolution, so the reckon speed is slow down. In addition, the algorithm for the ambiguity resolution by dual frequency P code pseudo-range constraint is presented.The methods of continuous filtering and the data overlapping are used respectively to achieve the continuous time and frequency transfer. Time transfer experiments are conducted, for the link of NTSC-NICT, the TDEV and MDEV is obviously hither than that of GPSCV and GPS P3 respectively whenτ<5d.The software has been developed for GPSCPTT processing, using the software package, through processing the comparison data from the laboratories of NTSC, USNO, PTB, et al, the results indicate that our results are at the same level as several references which based on GIPSY software. These results show that this software design is correct,the difference of our results between IGS's shows that the time stability is less than 0.1ns/d.Finally, the result of GPSCP smoothing pseudo-range observation is investigated. The smoothing method reduces the data sampling rate of the pseudo-range measurement and improves the short term stability of the time transfer.