不依赖电离层建模的多模GNSS接收机差分码偏差精确标定与可靠传递方法

Global Navigation Satellite Systems (GNSS) are well known to be affected by the differential code biases (DCB), which are no-negligible systematic errors in both signal transmitting and receiving chains, and need to be precisely corrected or calibrated for many GNSS applications and services. DCBs are commonly estimated together with ionosphere modeling, which are seriously influenced by the un-modeled ionospheric errors. This processing strategy has become one of the challenging issues limiting the further study of variation characteristics of receiver DCBs as well as real-time ionospheric total electron content (TEC) modeling and monitoring within current multi-GNSS environment. In view of this, this contribution proposes a method for receiver DCB handling with no consideration of ionosphere modeling. First, GNSS signal simulators are employed to study the potential hardware and environmental sources related to the variation of receiver code biases and to calibrate the “true” DCBs of the selected domestic and abroad GNSS receivers, since they present advantages in classifying and controlling numerous errors in GNSS data processing. Then a new approach is developed for transferring receiver DCB information on the basis of zero-baseline experiment, which is also applied and validated in real-time ionospheric TEC modeling with multi-GNSS observations. The proposed method overcomes the shortages of the current methods for DCB estimation with ionosphere modeling, and makes it possible to derive more reliable receiver DCB estimates. In a word, this project is the extension of the applicants’ recent research works. The outcome of relevance will enrich the theory and method of receiver code bias handling, and provide support and reference for precise receiver DCB correction in various real-time GNSS applications.

差分码偏差是现代空间大地测量GNSS精密应用服务必须精确处理与控制的系统性误差。现有差分码偏差处理方法通常与电离层建模同步进行，未模型化的电离层误差严重污染接收机差分码偏差估值的可靠性，成为影响接收机差分码偏差变化特征认识、制约多模GNSS实时高精度电离层反演等应用的关键瓶颈。针对此，本项目摒弃上述传统思路，首先利用导航信号模拟器误差类型可量化、误差大小可控制的优势，甄别影响接收机差分码偏差变化的主要硬件及环境因素，实现典型类型接收机差分码偏差“绝对量”的精确标定；然后通过构建零基线观测，设计接收机差分码偏差的精确传递方法，并在实时电离层监测中开展试验应用。上述研究思路不依赖于电离层建模，有效实现了接收机差分码偏差的精确标定与可靠传递。本项目是申请人已有研究工作的延续和拓展，研究成果可丰富接收机码偏差的处理理论与方法，并为多模GNSS实时应用中接收机差分码偏差的精确修正提供借鉴和参考。

差分码偏差是现代空间大地测量GNSS精密应用服务必须精确处理与控制的系统性误差。现有差分码偏差处理方法通常与电离层建模同步进行，未模型化的电离层误差严重污染接收机差分码偏差估值的可靠性，成为影响接收机差分码偏差变化特征认识、制约多模GNSS实时高精度电离层反演等应用的关键瓶颈。针对此，本项目摒弃上述传统思路，利用导航信号模拟器误差类型可量化、误差大小可控制的优势，建立了基于导航信号模拟器的接收机差分码偏差精确标定方法，量化分析了不同接收机硬件类型、环境温度及信号调制方式等对接收机差分码的影响，极大促进了对接收机差分码偏差产生机理和时变特征的认识。建立了一种基于改进载波相位平滑伪距且不依赖电离层建模的接收机差分码偏差时变特性分析方法，该方法为后续GNSS基准站接收机硬件延迟稳定度分析并提供相应的科学服务奠定了坚实的基础。基于本项目部分研究成果，项目团队研制的多模GNSS绝对码偏差产品已提交至IGN并免费发布给全球用户使用，是全球首家向IGS提供多模GNSS绝对码偏差产品的机构，极大提升了团队在多模GNSS偏差处理领域的国际影响力。