Research And Realization Of GLONASS Three-frequency Combination Positioning Algorithm

Because the third frequency information of GLONASS satellites will beprovided, the method,which is combining the three kinds of frequency ofGLONASS, is proposed based on GPS multi-frequency combined positioningprinciple. The features of three-frequency combination observations are longwavelength,weak ionospheric delay and weak observation noise. Andthree-frequency combination observations have obvious advantages in thecycle-slip detection and restoration. Combined three-frequency combinationobservations with the pseudo distance,the ambiguity can be quickly fixed. The threemajor research contents are as follows：1.Combination coefficient selection.The third carrier will be provided bymodernized GLONASS satellites frequency program. Starting from the GLONASScarrier phase observation model, three-frequency carrier phase combination ofGLONASS methed was researched. Assuring the integeral ambiguity, theionospheric delay and observation noise on the three-frequency of the combinedobservations was analyzed. According to long wavelength standard, weakionospheric delay standards, weak observation noise standards, some useful linearcombination was put forward to improve the positioning accuracy and speed.2. Cycle slip detection and restoration.Based on the features of modernizedGLONASS three-frequency linear combination observations, three linearindependently combinations are selected to simulateG3carrier phaseobservations. Using three-frequency combination observations combined withpseudorange, the detecting cycle slip model is established. The result of thisresearch shows that the ability to detect GLONASS carrier phase cycle slip isimproved.3. Baseline solution of combination observations.Firstly,the traditionalGLONASS baseline solution is introduced.Then,combinated withpseudorange,three linear independently combinations are selected, ambiguity of thecombined observations is solved.In this solution process,there are three group ofcombination coefficients to be selected. Confirmatory analysis shows that, just oneepoch observation, observation combination integer ambiguity can be obtained in this method.At last, single carrier phase observation value of the integer ambiguityis solved and the real-time and high precision positioning of GLONASS is realized.