Kalman-filter-based undifferenced cycle slip estimation in real-time precise point positioning
Kalman-filter-based undifferenced cycle slip estimation in real-time precise point positioning
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DOI：
10.1007/s10291-019-0894-3
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发表时间：
2019-10
期刊：
影响因子：
4.9
通讯作者：
Pan Li;Xinyuan Jiang;Xiaohong Zhang;M. Ge;H. Schuh
中科院分区：
文献类型：
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作者：
Pan Li;Xinyuan Jiang;Xiaohong Zhang;M. Ge;H. Schuh
全球导航卫星系统（GNSS）精密单点定位（PPP）需要连续的载波相位观测来获得高精度的解。精确校正信号中断引起的周跳是恢复数据连续性的关键。现有的大多数方法通常只使用中断后一个历元的数据进行实时周跳处理。在这项研究中，我们建议引入和估计周跳参数与标准的PPP参数，如位置，电离层延迟，和模糊度的情况下，可能的周跳被检测到，使用卡尔曼滤波器为基础的程序与未差分和未组合的PPP模型。采用整数搜索策略修复周跳。为了减少错误的整数固定的概率，一个严格的整数验证阈值的建议。因此，仅用一个历元的数据来修复所有的周跳是不容易的。我们的方法可以很容易地扩展到使用多历元观测，以提高周跳估计。一旦正确确定周跳，就可以立即实现连续PPP。通过三组实验对这种新方法进行了测试和验证，这些实验使用了2017年DOY 1-10国际GNSS服务运营的GPS和GLONASS站以及真实的车辆运动学数据。大量的实验结果表明，该方法可以正确地修复超过99.5%的周跳遭受再收敛。该方法平均需要1.5-2.5个历元的观测信息来修复周跳，实现快速再收敛。因此，定位性能显著提高。
Global navigation satellite system (GNSS) precise point positioning (PPP) requires continuous carrier-phase observations to achieve a solution of high precision. Precisely correcting cycle slips caused by signal interruptions is crucial for recovering the data continuity. Most of the existing approaches usually employ only data of one epoch after the interruption for real-time cycle slip processing. In this study, we propose to introduce and estimate cycle slip parameters together with standard PPP parameters, such as position, ionospheric delay, and ambiguities in the case that possible cycle slips are detected, using a Kalman-filter-based procedure with the undifferenced and uncombined PPP model. The integer search strategy is used to fix cycle slips. To reduce the probability of wrong integer fixing, a strict integer validation threshold is suggested. As a result, it is not easy to fix all cycle slips with only one epoch of data. Our approach can be easily extended to use multi-epoch observations to enhance the cycle slip estimation. Once the cycle slips are correctly determined, continuous PPP can be achieved instantaneously. This new approach is tested and validated with three groups of experiments using GPS and GLONASS stations operated by the International GNSS Service from DOY 1–10, 2017, and a real vehicle kinematic data. Numerous experimental results showed that the proposed method can correctly fix the cycle slips for more than 99.5% of epochs suffering from re-convergence. On average, this method takes observation information from about 1.5–2.5 epochs to fix cycle slips and realize rapid re-convergence. Consequently, positioning performance is significantly improved.