基于非差非组合模型的多频GNSS大网并行解算方法研究

Current huge GNSS reference network solutions (Huge network solution) based on the dual-frequency observable cannot fully exert the advantages of future GNSS that transmitting signals on multi-frequency with various modulation methods. Moreover, with the expansion of navigation constellations and reference networks along with the improvement of real-time application requirements, efficient huge network solution algorithms have become an urgent problem. Consequently, this investigation aims at the modeling of multi-GNSS, multi-frequency huge network solution based on zero-difference, zero-combination observable, with the emphasize on the external condition definition for the separation of signal delay parameters, ionosphere delay parameterization with a priori constrains as well as the rapid resolution of high-dimensional ambiguities. Furthermore, constructing the concurrent computation by introducing the Algorithms-by-Blocks with considerable efforts focus on the sub-matrix dividing with respect to the characteristics of the huge network parameters and information matrix, in order to break through the limitation of station number of whole reference network. Finally, module for integrated solution of huge network (>1000 stations) of multi-type observable of multi-GNSS will be developed and evaluated in terms reliability and the efficiency based on the real-tracking huge network data. The achievements is expected to improve the application level of multi-frequency GNSS technical in earth science.

目前以双频观测为基础所建立的大规模GNSS基准站网整体解算（大网解算）数学模型，不能够充分发挥多频点、多类型观测的优势。并且随着导航星座、基准站网规模的扩大及实时性应用要求的提高，高效的大网解算算法成为亟待解决的瓶颈问题。本课题拟研究采用非差非组合方法，构建多频多系统大网解算统一数学模型，重点解决多频、多类型观测值信号偏差估计、附加先验约束的电离层参数化模型以及高维模糊度快速固定等关键问题；研究采用矩阵分块算法的GNSS大网解算并行处理方法，突破大网整网解算的测站数量限制，重点分析非差非组合模型信息矩阵特征，设计针对性的参数排列与矩阵分块策略。在此基础上，研制多GNSS、多类观测量、大网（>1000个站）联合处理的核心软件模块，并采用实测大网数据对模型的正确性和算法的高效性进行验证。研究成果可促进多频GNSS大网解算在地球参考框架维持等地球科学中高水平应用。

随着我国BDS、美国GPS、俄罗斯GLONASS以及欧洲Galileo等系统的建设与发展，GNSS观测信号不断丰富，GNSS数据处理性能要求不断提高，在此背景下，项目组申请了基于非差非组合模型的多频GNSS大网并行解算方法研究项目，并按计划完成了相关研究。针对非差非组合多频多系统大网解算数学模型，项目组依据各类信号偏差变化趋势特征等，建立参数化模型，同时按最小约束条件引入基准以解决信号偏差与钟差之间的耦合性，实现了多类型信号偏差的稳定估计及高精度钟差估计；此外项目组针对非差非组合电离层参数化方法进行研究，提出了兼顾电离层时空特性的电离层先验约束模型DESIGN模型。针对大网整体解算计算性能，项目组基于矩阵分块算法，结合对GNSS 参数时变特性与时效性分析，设计了针对性的参数排列与子矩阵划分方法，实现了GNSS大网快速解算算法。基于多频多系统非差非组合数学模型及GNSS大网快速解算算法，项目组开发了GNSS大网解算软件平台Fusing，实现信号偏差、钟差、电离层、测站位移等多类参数联合快速处理。利用Fusing软件平台，项目组开展了若干研究工作并取得了相应成果：建立了7种接收机品牌，12类接收机的北斗伪距偏差改正模型，显著提升了北斗卫星钟差偏差及北斗单频SPP定位精度；将电离层先验约束模型DESIGN应用于单、双频PPP中，均实现了精度提升；分析了电离层闪烁对GNSS定位的影响；利用多项式函数和变异函数建立了卫星钟差模型，显著提升了卫星钟差估计精度；分析了GNSS PPP/INS紧组合定位测速性能，PPP/INS紧组合对定位和测速精度均有提升。