多频率多系统GNSS实时高频精密钟差快速估计关键技术

The real-time precise satellite clock estimation and its rapid update is an essential promise to realize the real-time positioning with centimeter-level accuracy in wide areas. The availability of multi-frequency and multi-constellation GNSS signals brings fresh perspectives to the investigation and application of real-time precise positioning technologies. However, a series of key problems should be solved for the estimation of high-frequency satellite clocks in real time. For the purpose of generating the high-frequency inter-recovered clock products in real time, we will study the theory and method for the rapid estimation of multi-frequency and multi-system satellite clocks, and overcome the relevant difficulties, such as establishing the multi-frequency and multi-system satellite clock estimation models, determining the self-consistent satellite clock reference, modeling the code and carrier phase biases between different frequencies and satellite systems, and estimating the satellite clock offsets within several seconds. The outcome of the project will be applied to real-time precise point positioning with ambiguity-fixed resolutions, and thus the real-time precise positioning technologies can satisfy the requirement of rapid centimeter-level accuracy in real time by many fields such as precision agriculture, oceanic resource investigation, and natural hazard early warning, which means a significant improvement for the BDS/GNSS applications and services.

卫星钟差产品的实时、高精度估计及快速更新是实现广域实时精密定位的前提。多频率多系统GNSS的发展为实时精密定位技术的研究与应用注入了新的活力，但也为实时估计高频率的精密卫星钟差带来了一系列需要突破和解决的关键难题。本课题拟开展多频率多系统GNSS实时高频精密卫星钟差快速估计的理论与方法研究，突破多频率多系统GNSS钟差模型的建立及基准定义，各种频间、系统间相位和伪距偏差参数的建模和估计，以及实时卫星钟差快速估计等关键技术，最终生成高频率的多频多系统GNSS实时整数钟差产品。预期研究成果将能够服务于实时精密单点定位固定解，拓展其在时效性较高的精密农业、海洋资源勘探和地质灾害预警等领域中的应用，提升BDS/GNSS的整体应用水平与服务性能。

PPP服务不需要密集的参考网，建设成本低且可实现全球广域实时快速分米级和厘米级位置服务。卫星钟差产品的实时、高精度估计是实现广域实时精密定位的前提。多频率多系统GNSS的发展为实时精密定位技术的研究与应用注入了新的活力，但也为实时估计高频率的精密卫星钟差带来了一系列需要突破和解决的关键难题。针对此，本项目着眼于多频率多系统GNSS实时高频精密卫星钟差快速估计的瓶颈问题进行了以下研究。1）研究了多频率多系统GNSS相位小数偏差估计算法，并在服务端设计有效的质量控制方法和手段，实现多频率多系统GNSS的相位小数偏差产品的精确估计。2）提出了非差模糊度多系统实时整数钟估计算法，实现了四系统实时整数钟的快速估计。生成的整数钟产品能够直接用于单站PPP模糊度固定。3）评估了实时整数钟的精度和可靠性进，并进行了实时PPP固定解试验，研究了实时整数钟产品模糊度固定效果，评估了实时PPP定位解精度。试验结果表明，与传统非差浮点卫星钟差相比，GPS、BDS、Galileo和GLONASS实时整数钟精度分别提高了53.0%、42.7%、63.7%和33.9%。处理100个测站的多系统观测数据，钟差估计计算效率提高了82.7%。利用生成的整数钟产品成功实现了实时PPP模糊度固定，东、北、天三方向精度较浮点解分别提高了77.2%、49.7%和52.7%。本项目研究成果将能够服务于实时精密单点定位固定解，拓展其在时效性较高的精密农业、海洋资源勘探和地质灾害预警等领域中的应用，提升BDS/GNSS的整体应用水平与服务性能。