Abstract Knowledge of differential inter-systems phase/code biases are critical to integrate observations from several different Global Navigation Satellite Systems. Many studies on tightly-combined model have mostly focused on the overlapping frequencies and short baselines, and fewer have focused on non-overlapping frequencies and medium-long baselines. Considering differential inter-systems code biases and inter-frequency code biases, we propose a tightly combined real-time kinematic model by a reparameterization process for non-overlapping frequencies among GPS/GLONASS/BDS systems. Compared with the traditional double-difference ambiguity parameter, we use single-difference ambiguity as the parameter to be estimated, which is not affected by reference satellite switching and wavelength limitation. The paper first analyzes the stability of differential inter-systems code biases and inter-frequency code biases with several zero and ultra-short baselines. Then, the paper tests the positioning performance under occlusion environment. The experiment shows that the tightly-combined model is more robust than the loosely-combined model and the average time to first fix is shortened by approximately 22.4%. At last, the paper compares the positioning performance of tightly-combined model, loosely-combined model, and tightly-combined model after calibration under the medium and long baselines. The experiment shows that the tightly-combined model after calibration is better than the tightly-combined model and loosely-combined model in the ambiguity resolution rate, initialization speed and positioning accuracy, respectively. Compared with intra-system loosely-combined model, the positioning accuracy of tightly-combined model after calibration is improved by 42.1%, 25.5%, and 32.3% in the three-dimensional directions, respectively.

中文翻译：

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考虑不同系统间码偏差的多系统紧密组合模型

摘要 不同系统间相位/代码偏差的知识对于整合来自几个不同全球导航卫星系统的观测至关重要。许多关于紧密组合模型的研究主要集中在重叠频率和短基线上，很少集中在非重叠频率和中长基线上。考虑到不同的系统间代码偏差和频率间代码偏差，我们通过对 GPS/GLONASS/BDS 系统之间非重叠频率的重新参数化过程提出了一个紧密结合的实时运动学模型。与传统的双差模糊度参数相比，我们使用单差模糊度作为待估计参数，不受参考卫星切换和波长限制的影响。论文首先分析了多个零基线和超短基线的差分系统间码偏差和频率间码偏差的稳定性。然后，本文测试了遮挡环境下的定位性能。实验表明，紧密结合的模型比松散结合的模型更稳健，首次修复的平均时间缩短了约 22.4%。最后，本文比较了紧结合模型、松散结合模型和紧结合模型在中长基线下校准后的定位性能。实验表明，标定后的紧组合模型在模糊度分辨率、初始化速度和定位精度上分别优于紧组合模型和松组合模型。