Research On Multi-frequency Cycle Slip Detection And Repair Method For BDS-3

With the rapid development of BDS-3 satellite navigation in China,BDS-3 multi frequency high-precision positioning has attracted extensive attention.The cycle slip generated in BDS-3 satellite precise positioning will directly affect the positioning accuracy,so it is very important to detect and repair cycle slip.This paper mainly focuses on the cycle slip detection and repair method of BDS-3 multi frequency(four frequency/five frequency).The main research contents include BDS-3 basic observation and observation error,BDS-3 multi frequency combination observation value theory,BDS-3 multi frequency observation combination method for cycle slip detection and repair,software design and other related issues.The main work and achievements of this paper are summarized as follows:(1)This paper introduces the development history and significance of BDS-3navigation and positioning system,the basic observation and positioning principle of BDS-3 positioning,analyzes the influence of four kinds of observation errors on navigation and positioning,and puts forward solutions to these four kinds of observation errors.(2)To solve the problem that the cycle slip detection and repair of BDS-3 multi frequency observations are not ideal,based on BDS-3 multi frequency(four frequency/five frequency)phase non geometric combination and pseudo range/phase non geometric non ionospheric combination,k-1(k=4 or 5)phase non geometric combination and one pseudo range/phase non geometric non ionospheric combination are proposed for cycle slip detection and repair of k-frequency BDS-3 data.In order to better improve the efficiency of multi frequency observation value combination selection,based on the theory of multi frequency combined observations,the selection of the optimal combination of multi frequency combined observations is analyzed according to the characteristics of long wavelength,weak ionosphere and low observation noise.The results show that the optimal combination of BDS-3 four frequency is [0,0,-1,1] in the multi frequency pseudo range/phase geometrically ionospheric free combination;The optimal combination of BDS-3 five frequencies is [-1,0,0,0,1].In the multi frequency phase non geometric combination,BDS-3 four frequency combination [0,-1,-2,3] has the best effect,while BDS-3 five frequency combination [0,-3,2,0,1] has the best effect.(3)In view of the problem that BDS-3 satellite is vulnerable to noise during observation,this paper adopts three different schemes to detect and repair cycle slips.Scheme I: least square method;Scheme II: the least square method and LAMBDA algorithm are combined;Scheme 3: The least square method,LAMBDA algorithm and carrier phase smoothing pseudo range method are combined.The test was conducted with the data of 1s and 30 s different sampling rates and different frequencies in the IGS database.The results showed that in the BDS-3 four frequency combination,the repair rate of Scheme I was 91.47%,that of Scheme II was 91.47%,that of Scheme III was99.95%,and that of Scheme III was the best.In BDS-3 five frequency combination,the repair rate of Scheme I,Scheme II and Scheme III is 95.91%,95.91% and 100%respectively.By comparison,the cycle slip repair rate of BDS-3 five frequency combination is better than that of BDS-3 four frequency combination.(4)The cycle slip detection and repair software is designed based on Python platform,which has the characteristics of convenient calculation,visual intuition and easy operation.It can better analyze and process the BDS-3 observation data and reduce the workload.