Researches On The Analysis Methods Of The Pseudorange Biases Characteristics For BeiDou B1C Signal

At present,various satellite systems have different degrees of pseudo-range bias.Which cannot be eliminated by difference,on the contrary,it may magnify its influence,thus affecting the ranging accuracy.With the rapid development of satellite navigation system and the continuous improvement of people's demand for positioning accuracy,the influence of pseudo-range bias on the high-precision application of GNSS cannot be ignored,which affects the further development of GNSS application.With Bei Dou global system put into use,B1 C signal as B1 frequency point of new civil navigation signal,at the same time shoulder the compatible with other system GNSS interoperability requirements,according to the characteristics of the BDS-3,in combination with pseudorange bias mechanism,from the satellite payloads and user receiver to conduct the thorough research to the pseudorange bias.The main work is as follows:1.Study on the influence of the characteristics of the payload end of Beidou satellite on the pseudo range bias of B1 C signalBased on the phenomenon of pseudo-range bias,the mechanism of pseudo-range bias loading end is studied.Based on the signal generation process on the satellite,the filter and high power amplifier which have great influence on the signal distortion are deduced,in which the filter will cause linear distortion,and the high power amplifier will cause nonlinear distortion.The simulation results show that both the filter and the high power amplifier have different effects on the signal distortion.On the premise of the same order,the effect of the ideal sharp cutoff filter on the signal distortion is the least,and the elliptical filter is the largest.Compared with high power amplifier with memory,no memory has less effect on signal distortion.2.Study on the influence of loop tracking mode on the pseudo distance bias of B1C signalBased on the signal processing process of the software receiver,the influence of the tracking loop on the pseudorange bias is studied.Based on the traditional closed-loop tracking,an open-closed-loop combined tracking method is proposed,and its tracking accuracy compared with the closed-loop tracking is verified by analyzing the measured satellite data.The research results show that: When the phase detection period of the closed-loop tracking and the joint tracking loop is 1:10,the difference between the two tracking modes is very small,which has little effect on the pseudorange bias.While joint tracking can greatly reduce the tracking time.3.Study on the influence of carrier loop and code loop phase discrimination mode on the pseudo distance bias of B1 C signalBased on the software receiver platform,the advantages and disadvantages of two carrier loop phase discrimination methods and four code-loop phase discrimination methods as well as their influences on the pseudorange bias are compared and analyzed.The results show that the simplified two-quadrant arctangent function phase discrimination method has little influence on the pseudo distance bias of B1 Cd and B1 Cpa,with the maximum difference of about 2mm,but has great influence on the B1 Cp signal as a whole.Therefore,it is suggested to adopt the two-quadrant arctangent function phase discrimination method for B1 Cp.In code-loop phase discrimination,incoherent lead minus lag power method or incoherent lead minus lag amplitude method has little influence on B1 Cd pseudorange bias,the maximum difference is about 2mm.Incoherent lead minus lag amplitude method has little influence on B1 Cp pseudorange bias.Therefore,it is suggested that when the user receiver is tracking B1 Cd signal,Incoherent lead minus lag amplitude method or incoherent lead minus lag power method is adopted.When tracking B1 Cp signal,incoherent lead minus lag amplitude method is adopted.4.Study on the influence of front-end bandwidth and correlation interval on the pseudo distance bias of B1 C signalStarting from the parameter setting of user receiver and based on the software receiver,the effects of different front-end bandwidths and relevant intervals on pseudo-range bias are analyzed through the measured data of 24 MEO satellites.The results show that the larger the difference between the user and the reference receiver,and the larger the difference of the front-end bandwidth,the larger the pseudorange bias.Group delay parameters can be broadcast between ISCS and navigation messages.In order to reduce the influence of this phenomenon on users,it is an effective method to minimize the relevant interval difference between the front-end bandwidth sum of users and the reference receiver to reduce the influence of pseudorange bias.