Benefits of the third frequency signal on cycle slip correction
Benefits of the third frequency signal on cycle slip correction
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DOI：
10.1007/s10291-015-0456-2
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发表时间：
2016-07
期刊：
影响因子：
4.9
通讯作者：
Xiaohong Zhang;Pan Li
中科院分区：
文献类型：
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作者：
Xiaohong Zhang;Pan Li
当载波相位观测用于高精度GNSS数据处理时，周跳检测和校正是一个重要问题，因此已经被深入研究。随着GNSS的现代化，在处理更多多频信号时，提出了周跳校正（CSC）问题。我们扩展了基于几何的方法，通过积分时差伪距和载波相位观测来估计三频周期滑移的整数个数，以及接收机时钟偏移、电离层延迟变化和接收机位移。可采用最小二乘模糊度去相关平差法。首先通过模拟试验研究了三频观测对周滑估计的好处。结果表明，加入三频观测可以显著提高模型强度，即使在距离或电离层延迟变化不明确的情况下，仍然可以获得可靠的三频CSC，理论成功率高于99.9%。由于在轨的北斗系统卫星都在发射三频信号，因此用实际的三频数据验证了三频CSC的性能。结果表明，在静态精确点定位（PPP）情况下，CSC的固定率可达99.1%，在运动情况下，固定率可达98.8%。对比了周期滑动未校正和周期滑动校正数据集的PPP解决方案，验证了三频CSC的正确性。修正周期卡泊后，东、北、垂直分量PPP解的标准差分别提高了31.1、30.7、37.6%，运动分量PPP解的标准差分别提高了42.0、53.8、39.7%。比较了双频和三频CSC的性能。结果表明，双频CSC的性能略差于三频CSC。这些结果表明，三频观测可以显著提高CSC的性能。
Cycle slip detection and correction are important issues when carrier phase observations are used in high-precision GNSS data processing and have, therefore, been intensively investigated. Along with the GNSS modernization, the cycle slip correction (CSC) problem has been raised to deal with more signals from multi-frequencies. We extend the geometry-based approach by integrating time-differenced pseudorange and carrier phase observations to estimate the integer number of triple-frequency cycle slips together with the receiver clock offset, ionospheric delay variations and receiver displacements. The Least-squares AMBiguity Decorrelation Adjustment method can be employed. The benefit of the third frequency observation on the cycle slip estimate is first investigated with simulation tests. The results show that adding the third frequency observation can significantly improve the model strength and that a reliable triple-frequency CSC with a theoretical success rate of higher than 99.9 % can still be achieved, even under the condition that the range or ionosphere delay variation is poorly defined. The performance of triple-frequency CSC is validated with real triple-frequency BDS data since all BDS satellites in orbit are transmitting triple-frequency signals. The results show that the fixing rate of CSC can reach 99.1 % in static precise point positioning (PPP) and 98.8 % in the kinematic case. PPP solutions with cycle slip-uncorrected and cycle slip-corrected data sets are compared to validate the correctness of triple-frequency CSC. The standard deviations of the PPP solution in east, north and vertical component, respectively, can be improved by 31.1, 30.7 and 37.6 % for static, and by 42.0, 53.8 and 39.7 % for kinematic after cycle slips are corrected. The performance of dual- and triple-frequency CSC is also compared. Results show that the performance of dual-frequency CSC is slightly worse than that of triple-frequency CSC. These results demonstrate that the performance of CSC can be significantly improved with triple-frequency observations.