Abstract: High-precision positioning jointed by three satellites of Beidou MEO,IGSO and GEO have an impact on the structure of the positioning model.Based on the sinusoidal elevation angle model,the tangent elevation angle model,the combination model of the elevation angle and the distance from the satellite to the ground station and the combination of the elevation angle,the distance from the satellite to the ground station and the signal-to-noise ratio,these four stochastic models are used to solve the short baseline with different length difference and different elevation difference.The effects of different stochastic models on the ambiguity resolution success rate and positioning accuracy of the short baseline with different length difference and different elevation difference are contrasted and analyzed.The result shows that for the baseline with short distance and small elevation difference,the sinusoidal elevation angle model have the highest ambiguity success rate and positioning accuracy; For baseline with long distance and large elevation difference,The tangent elevation angle mode have the highest ambiguity success rate,while the combination of the elevation angle,the distance from the satellite to the ground station and the signal-to-noise ratio have the highest positioning accuracy.

Key words: BDS triple-frequency, Single-epoch, Short baseline, Stochastic model