基于非差非组合模型的模糊度固定运动学定轨方法研究

Because of the simplicity of the data processing strategy and the suitability for the Earth’s gravity field determination, the kinematic orbit determination method gradually becomes a very important method for LEO’s orbit determination. Recent research shows that fixing the undifferenced ambiguities as integers can effectively undermine the systematic bias in the kinematic orbits. However, in the traditional Melbourne-Wubbena(MW) and LC combination model, the fixing success rate of the narrow-lane ambiguity is relatively low because of the very short narrow-lane wavelength. This is the key to further improve the accuracy and continuity of the kinematic orbits. Thus, this project will focus on the uncombined undifferenced model, and will study on: (1) Considering the quick variations of the ionospheric delays in the LEO’s observables, we will study on the cycle-slip detection and repair method; (2) Estimation of the GPS satellite L1 and L2 carrier phase uncalibrated phase delays (UPDs) using the uncombined undifferenced model, especially a rigorous method in theory and the corresponding computationally effective method will be put forward and verified; (3) Modeling the receiver clock model for LEOs to improve the continuity of the orbits and reduce the jumps in the orbits simultaneously; (4) To improve the fixing success rate and avoid of wrong fixing, the ambiguity estimation, resolution and testing method for the uncombined undifferenced model will be analyzed. Finally, with the improved method and algorithms, the high success rate of the ambiguities based on the uncombined undifferenced model can be accessed, and then high-precision kinematic orbits for LEOs can be achievable.

低轨卫星运动学定轨方法具有数据处理简单且适用于地球重力场反演等优点，具有重要应用价值。固定非差模糊度可以有效削弱运动学轨道中的系统偏差。然而,传统模型中窄巷波长仅为10.7cm,其固定成功率偏低,是限制运动学轨道精度与连续性进一步提升的关键。为此，本项目拟研究基于非差非组合模型的模糊度固定运动学定轨，具体内容包括：（1）针对低轨卫星电离层延迟变化大的特点，提出适用于低轨卫星的周跳探测与修复算法；（2）研究基于非差非组合模型的GPS卫星载波相位小数偏差估计严密及快速方法；（3）研究接收机钟差建模方法，提高运动学轨道的连续性并减少轨道异常；（4）研究非差非组合模糊度估计、固定及检验方法，提高模糊度固定成功率并避免固定错误。最终，实现基于非差非组合模型的模糊度固定运动学定轨，显著提升模糊度固定成功率，为确定高精度低轨卫星运动学轨道奠定坚实基础。

精密运动学轨道是各类重力卫星任务得以成功实施的基础。 基于GNSS载波相位进行运动学定轨的挑战是如何将模糊度进行正确固定，该技术是GNSS数据处理中的核心难题。随着GNSS技术的发展，非差非组合模型具有保留所有待估参数的优势，因此研究基于非差非组合模型的运动学定轨方法是本课题的研究内容。.课题研究始终围绕着基于非差非组合模型的运动学定轨展开深入研究，在过去四年里取得了显著研究成果，具体包括：（1）研究了地影模型对非差非组合定位的影响，为实现连续高精度定位定轨提供了基础；（2）提出了附加加速度约束的低轨卫星周跳探测新方法，解决了低轨卫星定轨中数据异常等棘手的数据预处理难题；（3）提出了一种全新的加速度约束动力学定轨方法，该方法在有效地利用低轨卫星动力学模型的基础上，实现了高精度高效率运动学定轨。（4）提出了一种基于非差非组合模型的全局周跳探测方法，该方法适用于未来多频多系统定位定轨模型。

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