Research On GNSS Single-difference Carrier Phase Time Transfer Technique

Time is one of the basic parameters of physics.High-precision time and frequency service plays an indispensable role in many basic researches and application fields,and remote time transfer is an important means to achieve high-precision time and frequency service.GNSS carrier phase time transfer has become one of the research hotspots at home and abroad,because of its high precision,simple equipment and convenient operation.GNSS carrier phase time transfer consists of non-difference mode and single-difference mode.The principle of carrier phase time transfer of singledifference mode is basically the same as that of common view method.The two receivers of the two observation stations simultaneously observe the same satellite,and then obtain the single-difference solution between stations,and resolve the receivers clock difference between the two stations,to realize the time transfer between the two stations.In this paper,the GNSS single-difference carrier phase time transfer method is studied.The traditional GPS single-difference carrier phase time transfer is realized by using IGS observation data for the short baseline and the medium-long baseline.Then,on the basis of the model,a single-difference carrier phase time transfer method of fixing phase ambiguity is presented.The results show that:(1)In the case of short baseline and medium-long baseline,the traditional GNSS single-difference carrier phase time transfer can achieve two-station time comparison of sub-nanosecond order.(2)With the increase of baseline length,time transfer precision of the GNSS singledifference carrier phase decreases due to the decrease of the number of satellites that can be observed together by two observation station.The main contents of the paper are as follows:Firstly,the principle of GNSS single-difference carrier phase time transfer is introduced,according to the observation model,the error influencing factors of GNSS single-difference carrier phase time transfer are analyzed,and the corresponding error correction method is given.And the GNSS single-difference carrier phase time transfer data processing methods are studied,including gross error elimination of observation data,cycle-slip detection and repair,precision ephemeris interpolation method,and carrier phase smoothing code pseud-orange method,etc.Secondly,the traditional GNSS single-difference carrier phase time transfer method is studied.Single-difference carrier phase time transfer is realized by using the IGS observation data,and GODE-USN7 ultra-short baseline,PTBB-OPMT short baseline and USN7-STJO medium-long baseline time comparison links were selected for testing,and the time transfer results were analyzed.Finally,commonly used GNSS carrier phase ambiguity fixed method is introduced.For the characteristics of single-difference carrier phase time transfer,a phase ambiguity fixed method for single-difference carrier phase is given,and the singledifference carrier phase time transfer method of fixing phase ambiguity is tested.