A double-differenced cycle slip detection and repair method for GNSS CORS network
A double-differenced cycle slip detection and repair method for GNSS CORS network
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DOI：
10.1007/s10291-015-0452-6
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发表时间：
2016-07-01
期刊：
影响因子：
4.9
通讯作者：
Zhao, Lewen
中科院分区：
文献类型：
--
作者：
Chen, Dezhong;Ye, Shirong;Zhao, Lewen
载波相位测量周跳的检测和修复困难是GNSS定位和导航服务持续高精度的关键限制。我们提出了一种用于 CORS 网络数据预处理的自动周跳检测和修复方法。该方法联合使用双差（DD）无几何（GF）组合和计算几何距离校正的无电离层观测（IF-OMC）来估计双频观测中的周跳。 DD GF组合仅受电离层残差影响，除GPS L1/L2频率上的(77, 60)等特殊对外，可用于高可靠性的周跳检测。 IF-OMC可观测量的检测原理是，当当前历元发生周跳时，与前历元相关的不连续性较大。采用所提出的检测方法可以克服这两种组合的缺点。周跳对 (77, 60) 对 GF 组合没有影响，而 14.65 m 的变化是使用 IF-OMC 算法从 GPS L1/L2 观测得出的。使用预先确定的站点坐标作为精确值，我们发现 DDIF-OMC 组合对于 200 公里 CORS 基线的精度为 18 毫米。因此，利用DD GF和IF-OMC方程可以正确且唯一地确定双频观测中的周跳。通过在安静电离层下从 CORS 网络收集的观测数据中添加模拟周跳来验证所提出的方法，并证明该方法是有效的。此外，该方法还通过强烈的电离层活动期间的观察进行了评估，电离层活动产生了广泛的周跳。结果表明，除了与长数据间隙相关的两个异常之外，该算法可以检测和修复所有周跳。
The difficulty to detect and repair cycle slip of carrier phase measurements is a key limit for continuously high accuracy of GNSS positioning and navigation services. We propose an automated cycle slip detection and repair method for data preprocessing of a CORS network. The method jointly uses double-differenced (DD) geometry-free (GF) combination and ionospheric-free observation corrected for the computed geometrical distance (IF-OMC) to estimate the cycle slips in dual-frequency observations. The DD GF combination, which is only affected by the ionospheric residual, can be used to detect cycle slips with high reliability except for special pairs such as (77, 60) on GPS L1/L2 frequencies. The detection principle of the IF-OMC observable is such that there is a large discontinuity related to the previous epoch when cycle slips occur at the present epoch. The disadvantages of these two combinations can be overcome employing the proposed detection method. The cycle slip pair (77, 60) has no effect on the GF combination, while a change of 14.65 m is derived from GPS L1/L2 observations using the IF-OMC algorithm. Using pre-determined station coordinates as precise values, we found that the accuracy of the DDIF-OMC combination was 18 mm for a 200-km CORS baseline. Therefore, cycle slips in dual-frequency observations can be correctly and uniquely determined using DD GF and IF-OMC equations. The proposed method was verified by adding simulated cycle slips in observations collected from the CORS network under a quiet ionosphere and shown to be effective. Moreover, the method was assessed with observations made during intense ionospheric activity, which generated extensive cycle slips. The results show that the algorithm can detect and repair all cycle slips apart from two exceptions relating to long data gaps.