Research On Rapid Determination Method Of Navigation Satellite Precise Clock Offset

Satellite clock offset plays an important role in the precision positioning.How to achieve quickly determining the satellite clock offset is the key to achieve the real-time precise positioning system.The theory and method of precision clock offset calculating is systematically studied in this thesis.The observation model,the error correction model and parameter estimation method of satellite clock offset calculating are introduced in detail.The main work is summarized as follows:1.The satellite clock offset data preprocessing method is in-depth studied of.As for receiver clock jump's influence on the cycle slip detection,it is focused on the method to detect clock jump.Taking advantage of the feature that receiver clock jump will not affect the Doppler observation,it proposes a cycle slip detection method with real-time un-differential data considering receiver clock jump,based on Doppler observations,which effectively avoids the possibility of mistaking receiver clock jump as cycle slip.As is theoretically proved that when the satellite clock systematic deviation is less than 250 ns,the systematic deviation of relative clock offset is completely absorbed by the receiver clock offset,which does not affect the precise point positioning results.Then the above conclusion is verified through the experiment,where the results show: precise point positioning deviation caused by the systematic deviation on the three-axis direction is no more than 0.1 mm,which is negligible.2.For satellite clock offset ultra short-term forecasting,the forecast effects of linear model,quadratic polynomial model,gray model and quadratic polynomial model based on epoch difference are comparatively analyzed according to the experiment data.The results indicate that: the four methods get equivalent accuracy as a whole in ultra-short-term clock offset forecasting,and prediction accuracy in 5 minutes of the clock offset on satellite with different types of atomic clocks is better than 0.36 ns.For a small sample of the satellite clock offset ultra-short-term forecasting,the experiment analyzes the clock offset prediction accuracy of the same satellite at different times,and the results show that: prediction accuracy depends on the small-scale changes of the satellite clock offset during that period and the length of the forecast time.3.Precise satellite quickly solving experiments are done by using the data from 13 IGS stations,where most of the clock offset accuracy is less than 0.3ns.When the calculated satellite clock offset is applied to PPP,horizontal positioning accuracy is less than 5cm,and vertical positioning accuracy is less than 10 cm,which are in the same order of positioning accuracy compared with PPP with IGS final production.For DCB will affect satellite clock error computation problems,the experimental data proved that DCB can cause systemic deviation to the satellite clock error influence,different satellite has different systemic deviation,maximum deviation will be more than 2 ns system.4.Aiming at precise positioning by using the regional reference station network data,the positioning method of the satellite clock offset and the coordinates of moving station is studied.With IGS station data dynamic simulation,the experiment shows that the joint solving mode can achieve centimeter-level positioning accuracy,and it just makes use of the precise ephemeris data,not limited by the clock offset interpolation accuracy,sample rate and distance limitations.For this feature the experiment is done and the results prove that no matter inside or outside the local area network,it can achieve the centimeter-level positioning accuracy.5.Further research is done on the satellite clock offset integrity monitoring algorithm and a real-time satellite clock anomaly monitoring algorithm is proposed based on the forgetting factor least square algorithm,which overcomes the shortcomings of the traditional monitoring tools with high cost and poor real-time performance.In the Experiment the clock offset monitoring capabilities of the two algorithms RFFLS and LS are analyzed,where the results indicate that: both the clock offset monitoring capability and time-consuming of RFFLS are significantly superior to LS,thus there are obvious advantages of RFFLS algorithm in real-time applications.