| Processing of high precision measurement data is the foundation of precise positioning, precise orbit determination and time frequency synchronization in navigation satellite system. With the development of navigation satellite system broadcasting three or four carriers, more redundant measurements can be used. In order to obtain short initializing time and high precision, processing methods of multi-frequency measurement data need to be optimized. The Beidou Global Navigation Satellite System(BDS) is planing to broadcast four navigation frequencies include a S spectrum signal. Four techniques are studied in this dissertation, which is eliminating ionospheric delay using multi-frequency pseudoranges, smoothing pseudorange using multi-frequency carrier phases, fast ambiguity resolution of multi-frequency carrier phase at long baseline, time frequency transfer and stability estimation based on carrier Doppler. In summarize, the following innovative researches are studied:(1) The pseudorange noise is amplified when eliminating ionosphere delay. A general algorithm of eliminating ionospheric delay using multi-frequency pseudoranges is presented. For two-frequency, three-frequency, four-frequency BDS users, algorithms of eliminating ionospheric delay based on least measurement noise rule are analyzed, which support the design of global BDS’s new signal. The theoretical analysis and test results show that global BDS can raise the no ionospheric delay combined pseudorange precision and positioning precision by 5~8 times than regional BDS by broadcast a S spectrum signal. Besides, the precision of no ionospheric delay combined pseudorange in global BDS is 2~3 times than in Galileo System, although both of them broadcast four-frequency navigation signal and on same noise level.(2) According to the new property of four-frequency in modern GNSS, the algorithm of multi-frequency carriers phase smoothing pseudorange is researched, and general formula is proposed. The new method of four-frequency-first-order carriers phase smoothing pseudorange based on least variance random error rule is proposed. It is illuminated by theoretic analyzing and test results that in global BDS, residual error of pseudorange can be reduced to millimeters, which is 2~3 times better than in regional BDS, thus raising the positioning precision 5 to 8 times.(3) At long baseline, for multipath and ionospheric residual bias, classical CIR could not resolve carrier phase ambiguity at single epoch. An approach of first resoluting combined carrier phase ambiguity then resoluting basic carrier phase ambiguity by a converting matrix is presented. This algorithm is in a rule of using some long wavelength and little total error combined carrier, and the least condition number of converting matrix. Utilizing smoothed dual-frequency pseudorange and combined carrier phase with resolved ambiguity, the ionospheric delayis eliminated, and success rate of basic carrier ambiguity resolution at single epoch is improved. New algorithm can extend the suited baseline form less than 100 km to above 1000 km, and raise the success rate of ambiguity resolution at single epoch from 7% in classical CIR to 100%.(4) Aiming at time and frequency synchronization and frequency stability estimation of long baseline ground station in navigation system, an algorithm of remote frequency stability estimation based on Two-Way Satellite Time and Frequency Transfer(TWSTFT) and Three-Cornered Hats(TCH) is proposed. This algorithm calculate the frequency difference of two stations using carrier Doppler observation, overcoming the shortage of poor precision in short-term stability estimation using pseudorange TWSTFT. By frequency transfering between each two sations in three stations, the frequency stability of one station can be estimated. Using this algorithm process a operating data of BDS, the result shows that the stability can reach 10-13 at τ=1s, and 10-15 at τ=10000s.The research results of three-frequency measurement data processing algorithm and remote frequency stability estimation algorithm in this dissertation have been used in some projects of regional BDS, such as observation and communication system in mastr station and time synchronization and injecting station, and have supported the project research and equipment development in fields of precise positioning, precise orbital determination and precise time frequency transfer. The four-frequency measurement data processing algorithm can be applied in global BDS research, and also applicable to GPS, Galileo and other GNSS system.
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