实时轨道和钟差的精度与质量是实时精密定位服务可靠性的核心保障。尽管IGS提供了多种实时卫星轨道和钟差产品，但其在连续性和稳定性方面仍面临挑战，需要进一步优化以提升服务质量。因此，有必要深入分析各家IGS实时产品，研究多GNSS系统实时轨道钟差产品的综合方法，为实时高精度GNSS定位服务提供可靠的基础支持。本文的主要研究内容如下：

（1）本文对当前五大分析中心发布的实时产品质量进行了评估。结果显示，CAS发布的GPS产品具有最高的可用性，而GFZ和WHU对于GAL的卫星可用性最高；在BDS卫星方面，CAS、GFZ、WHU三家相较于CNES表现更好。在三维轨道精度方面，CNES的GPS卫星表现最佳，各方向精度均在3cm以内。在卫星钟差精度方面，实验结果表明：WHU的GPS表现最优，GMV的GAL卫星在三维轨道和卫星钟差精度上均为最佳，WHU的BDS-2卫星在三维轨道精度上表现最佳，而CNES的BDS-2卫星在钟差精度上最优，WHU的BDS-3轨道和钟差产品精度表现最好。

（2）针对不同IGS分析中心提供的实时轨道产品存在参考基准不一致问题，采用Helmert七参数模型估计产品间的相似变换参数，以削弱不同轨道产品参考基准不统一和系统偏差的影响。针对实时轨道产品接收过程中可能出现的数据中断问题，利用拉格朗日插值法修复残缺数据，并通过实验确定了GPS、GAL和BDS-3最低插值阶数。基于上述轨道预处理流程，采用等权、先验权和基于均方差因子的定权策略进行综合轨道估计，实验结果表明：综合后的实时轨道精度相对于单个分析中心轨道精度最低提升了8.8%，相较于IGS综合产品提升了14.3%以上。然后比较了不同综合策略的效果，其中均方差因子定权策略表现最好。

（3）对于实时钟差中的异常值，本文采用基于中位数的小波变换探测法进行处理，有效去除了异常值。针对IGS实时钟差综合中的跳变问题，采用实时预测和跳变补偿方法进行处理，以消除由参考基准缺失或参考钟切换引起的跳变。基于这些实时钟差预处理方法，本文采用抗差定权和多角帽法进行综合钟差，实验结果表明：综合后的GPS、GAL实时卫星钟差STD相对于单个分析中心钟差STD至少降低了8.6%，相较于IGS综合产品降低了21.6%以上；综合后的BDS-3IGSO/MEO实时卫星钟差STD相较于单个分析中心钟差和综合钟差产品STD明显降低。接着对比了两种策略的综合效果，实验表明多角帽法略优于抗差定权。

（4）最后，本文研发了一个基于MFC的多系统GNSS实时轨道/钟差产品综合软件，并进行数据完整率验证，最后基于实时综合产品进行了静态定位实验和实时时间传递实验，实验结果表明：该软件生成的综合产品在数据完整率上展现出显著优势，且综合产品达到了厘米级的定位精度和亚纳米级的时间传递精度，证明了软件的实用性和综合产品的有效性。

The accuracy and quality of real-time orbit and clock bias are crucial for the reliability of real-time precise positioning services. Although the International GNSS Service (IGS) provides various real-time satellite orbit and clock bias products, challenges remain in their continuity and stability, necessitating further optimization to enhance service quality. Therefore, it is essential to thoroughly analyze various IGS real-time products and study the integrated methods of multi-GNSS system real-time orbit and clock bias products to provide a reliable foundation for real-time high-precision GNSS positioning services. The main research contents of this paper are as follows:

(1)This paper evaluates the quality of real-time products released by the five major analysis centers. The results indicate that the GPS products from CAS have the highest availability, while GFZ and WHU have the highest satellite availability for GAL. For BDS satellites, CAS, GFZ, and WHU perform better compared to CNES. Regarding the three-dimensional orbit accuracy, CNES's GPS satellites perform the best, with accuracies within 3 cm in all directions. In terms of satellite clock bias accuracy, the experimental results show that WHU's GPS performs the best, GMV's GAL satellites have the best three-dimensional orbit and satellite clock bias accuracy, WHU's BDS-2 satellites have the best three-dimensional orbit accuracy, while CNES's BDS-2 satellites have the best clock bias accuracy, and WHU's BDS-3 orbit and clock bias products perform the best.

(2)To address the issue of inconsistent reference frames among real-time orbit products provided by different IGS analysis centers, the Helmert seven-parameter model is used to estimate the similarity transformation parameters between products, mitigating the impact of inconsistent reference frames and system biases. To address potential data interruptions during the reception of real-time orbit products, the Lagrange interpolation method is used to repair missing data, and experiments determine the minimum interpolation order for GPS, GAL, and BDS-3. Based on the above orbit preprocessing workflow, combined orbit estimation is conducted using equal weighting, a priori weighting, and variance factor-based weighting strategies. The experimental results show that the accuracy of the combined real-time orbit improved by at least 8.8% compared to the orbit accuracy of individual analysis centers, and by more than 14.3% compared to the IGS combined products. A comparison of different combination strategies indicates that the variance factor-based weighting strategy performs the best.

(3) For outliers in real-time clock bias, this paper employs a wavelet transform detection method based on the median to effectively remove outliers. To address clock jumps in the IGS real-time clock combination, real-time prediction and jump compensation methods are used to eliminate jumps caused by reference frame shifts or reference clock switches. Based on these real-time clock preprocessing methods, robust weighting and the Helmert variance component estimation method are used for combined clock bias. The experimental results show that the combined GPS and GAL real-time satellite clock bias standard deviations (STDs) are reduced by at least 8.6% compared to the clock bias STDs of individual analysis centers, and by more than 21.6% compared to the IGS combined products. The combined BDS-3 IGSO/MEO real-time satellite clock bias STDs are significantly reduced compared to the clock bias STDs of individual analysis centers and combined clock bias products. A comparison of the two combination strategies shows that the Helmert variance component estimation method is slightly better than robust weighting.

(4)Finally, this paper developed a multi-system GNSS real-time orbit/clock bias product combination software based on MFC and validated data integrity. Static positioning experiments and real-time time transfer experiments were conducted based on the combined real-time products. The experimental results show that the combined products generated by the software exhibit significant advantages in data integrity and achieve centimeter-level positioning accuracy and sub-nanosecond-level time transfer accuracy, demonstrating the practicality of the software and the effectiveness of the combined products.

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