多频多模GNSS广义码偏差参数化方法及其精确估计

The development of multi-frequency and multi-GNSS produces a series of signal biases. Nowadays, steadily increasing number of types of biases should be dealt with due to the new emerging satellites and signals. The proper handling of these biases arouses great interest in GNSS community, and is an essential premise to realize the compatibility and interoperability between different satellite systems. Currently, the definition of the various biases is ambiguous and they are often termed as in different forms. In addition, the consistency of various biases is poor since they are commonly estimated independently. Moreover, the bias correction model is complex, and thus it is difficult for the ordinary users. This project intends to address the above issues. First, we will study the mechanism and variation characteristics of all relevant code biases. Then, the concept of "generalized code bias" is proposed, and its definition and parameterization method are investigated. In addition, the mathematical model of generalized code bias estimation is established, in which all relevant code biases can be extracted fully consistently. Finally, a "quasi" absolute code bias correction method is proposed, which provides a simple and uniform bias correction model for GNSS positioning and navigation users..This project is in line with the needs of the current situation. It is of great academic value and application value to promote compatibility and interoperability among multi-GNSS.

多频多模GNSS的发展衍生了一系列信号偏差，如何处理这些偏差是当前国际卫星导航领域的热点研究课题，合理定义并参数化各种信号偏差是实现多频多模GNSS兼容与互操作的重要前提。本项目拟针对当前信号偏差种类多、定义方式不明确不统一，不同码偏差参数之间的一致性较差，偏差参数校正方法复杂等问题，深入研究多频多模GNSS码偏差的产生机制和变化机理；从更具普适性的角度，提出“广义码偏差”的概念，并建立广义码偏差的定义方式及参数化方法；构建广义码偏差估计的数学模型，发展码偏差精确估计理论与方法；在此基础上，提出一种“准”绝对码偏差校正方法，为导航定位用户提供简便、统一的偏差校正方法和模型。本项目研究符合当前多频多模GNSS快速发展的需要，可为实现多频多模GNSS兼容与互操作提供支撑，对于丰富多频多模GNSS数据处理的理论和方法，推动多频多模GNSS融合导航定位技术的发展具有重要的学术价值和应用价值。

针对当前多频多模GNSS发展所衍生的一系列信号偏差，项目开展了广义码偏差参数化方法及其精确估计的研究。考虑到现阶段多频多模偏差种类繁多、定义不明、使用不便等突出问题，提出了“绝对码偏差（OSB）”的概念，并建立OSB的定义方式及参数化方法，构建了OSB估计的数学模型，利用IGS和iGMAS实测数据估计得到了GPS、Galileo、GLONAS和BDS四系统的绝对码偏差。在此基础上，全面比较分析了各系统OSB的内符合精度、外符合精度，以及月稳定度。结果表明，估计结果与其他机构提供的产品具有一致性；各卫星不同类型的码偏差稳定度基本一致；同一频率上的码偏差相近，Galileo E5a、E5b和E5的码偏差相近，BDS B2a、B2b和B2的码偏差相近。考虑到GLONASS采用频分多址技术以及BDS-2和BDS-3之间存在信号体制的差异，提出一种顾及频间偏差的GLONASS绝对码偏差估计方法，并将BDS分成两个独立的系统进行OSB估计。结果表明，采用本项目提出的方法，精度提升显著。项目成果对于丰富多频多模GNSS数据处理理论和方法，推动多频多模GNSS 融合导航定位技术的发展具有重要的学术价值和应用价值。