Study Of GNSS Multiple Frequency Combination Coefficient Determinationbased On Genetic Algorithm

Efficiently and accurately fixed inter ambiguity is always a key problem need to be solved in the program of GNSS fast and high precision positioning.Traditional ambiguity resolving method usually have three steps: first,neglect the integer character of ambiguities,then,use float solution and it’s covariance matrix with specific parameter estimation rule searching the right inter ambiguity,finally,test the effectiveness of the assessment value,if pass the test then use the assessment value to correct other float solution.With the increase in the number of carrier phase signals arriving from the space,it provides new methods of ambiguity resolution.This text is based on the identification of the coefficient of the multi-frequency carrier phase combined observation,and focus on resolving the integer ambiguity of the combined observation.Centered on the coefficient selection and integer ambiguity resolution two aspects expend theoretical derivation,and use experiment to check the result.Main research could be summarizing as follows:1.Based on the background of this article,satellite navigation and positioning system of the signal characteristics are analyzed besides analyses the error factors that affect the positioning accuracy in carrier phase positioning and linear combination model,and presents quantitative indicators for combination observation errors.2.We introduce genetic algorithm to the coefficient selection of combined observation,first given the train thoughts of the integer programming method and function method,then taking Compass and Galileo system for example,select a set of combination observations which meet contain characteristic demand.3.Review the M-W model which used pseudo-range and phase combined observation,and calculate the success rate of GPS and Galileo system using TCAR method.Calculate success rate in each step of MCAR method using selected Galileo optimal combined observation.Using real data check out the selected combined observation of Compass based on Geometry-free model,and resolve the ambiguity of combined observation,and then get the ambiguity of carrier phase double difference observation by matrix transformation method.It turned out that the error of selected combined observation is less than half of wavelength,and the ambiguity of carrier phase double difference observation can be fixed correctly.