The Accurate Detection,Repair And Reliability Evaluation Method For Cycle Slip In GNSS

With the expanding of application field and application environment of positioning technology in GNSS,it is necessary to continuously improve the precise positioning data processing method in GNSS to ensure the availability of positioning technology and the reliability of positioning results.Among them,the cycle slip detection and repair is a very important part in the process of precise positioning data processing in GNSS.Aiming at the problems that there are many current cycle slip detection and repair methods but there are application limitations,and it is difficult to accurately evaluate the results.The research on accurate detection,repair and reliability evaluation of cycle slip in GNSS precision positioning are carried out in this paper.The main work and conclusions are as follows:(1)The basic knowledge of GNSS cycle slip is elaborated,and the influence of cycle slip on positioning is analyzed.The basic observations of GNSS positioning and the main sources of errors in GNSS positioning are introduced.The generation mechanism and characteristics of cycle slip are explained.The influence degree of cycle slip on the positioning results is analyzed from the perspective of theoretical and measured data.(2)A highly adaptable method for GNSS cycle slip detection and repair is proposed.Aiming at the problem that few cycle slip detection methods can meet the data processing needs in multiple situations at the same time,a modern data processing method that comprehensively uses carrier and pseudo-range observations is proposed to achieve precise detection and repair of cycle slip in various situations.Pseudo-range and carrier observations after the satellitedifference and the epoch-difference are used to establish the observation equation with cycle slip parameter in this method,and the state equation is established based on the slowly changing characteristics of satellite-ground distance.Then,a more accurate star-ground distance state parameter are obtained through initialization filter,and a satellite-ground distance state equation including cycle slip parameters is established.Then,the state equation and observation equation containing cycle slip parameters are combined,and the cycle slip real solution of each frequency observation value is obtained through Kalman filter,and then the cycle slip repair value can be get through the LAMBDA method.The data verification shows that the method is suitable for accurate detection and repair of cycle slips under all kinds of conditions other than active ionosphere.(3)A cycle slip detection method with no-blind-spot and against ionospheric interference based on triple-frequency combination is proposed.Aiming at the problems that the new method described above is difficult to accurately detect the cycle slip in the active period of the ionosphere,and the existing triple-frequency combination method is prone to have blind spots,a cycle slip detection and repair method based on triple-frequency combination that is resistant to the influence of the ionosphere and has no blind spots is proposed.This method first constructs a triple-frequency geometric free phase combination and a triple-frequency STPIR combination,and uses these two combinations to construct a common blind spot model,and then the coefficient constraint conditions of the triple-frequency pseudo-range phase combination can be obtained.Based on this condition,The triple-frequency pseudo-range phase combination that can detect the first two combined blind spots can be constructed.After experimental verification,the method can accurately detect and repair triple-frequency observation data without blind spots in the stable and active periods of the ionosphere.(4)An evaluation method of GNSS cycle slip detection and repair effect is proposed.Aiming at the problems that the reliability of the obtained cycle slip repair value and the applicability of the selected cycle slip detection and repair method,based on Bayesian estimation theory,a practical formula for calculating the posterior probability of the cycle slip repair value as true is given.The posterior probability of the cycle slip repair value is used as an index to evaluate the reliability of the repair result.The calculation examples show that the evaluation method can accurately evaluate the reliability and adaptability of the cycle slip detection and repair method.In addition,the detection effects of the two detection methods proposed in this paper under active ionospheric conditions are evaluated and analyzed.The results shown that the cycle slip detection method without blind spots based on the triplefrequency combination is significantly better than the highly adaptive cycle slip detection method based on Kalman filter in GNSS for the triple-frequency observation data in the active area of the ionosphere.(5)The three methods proposed in this paper are applied to different practical projects,and the specific application process and calculation demonstration are given.The application results show that the method proposed in this paper has a good effect on the detection,repair and evaluation of cycle slip for practical projects.