Calibration errors on experimental slant total electron content (TEC) determined with GPS
Calibration errors on experimental slant total electron content (TEC) determined with GPS
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DOI：
10.1007/s00190-006-0093-1
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发表时间：
2007-02-01
影响因子：
4.4
通讯作者：
Radicella, S. M.
中科院分区：
文献类型：
--
作者：
Ciraolo, L.;Azpilicueta, F.;Radicella, S. M.
全球定位系统（GPS）已成为电离层研究的有力工具。此外，电离层校正对于全球导航卫星系统所需的增强系统也是必要的。双频载波相位和码延迟GPS观测相结合，以获得电离层观测值有关的倾斜总电子含量（sTEC）沿着卫星接收器的视线（LoS）。这个可观测值受到由发送和接收硬件引起的频率间偏差[IFB;通常称为差分码偏差（DCB）]的影响。这些偏差必须估计和消除的数据，以校准从GPS观测获得的实验sTEC。基于对双频GPS接收机对电离层观测值单差的分析，本研究解决了两个主要问题：（1）评估由码延迟转换为载波相位电离层观测值的误差，通过所谓的调平过程，应用于减少数据的载波相位模糊度;（2）评估接收机IFB的短期稳定性。得出的结论是：（1）经调平的载波相位电离层可观测值受到系统误差的影响，该系统误差由通过调平过程的码延迟多径产生;以及（2）接收器IFB可能在1天内经历显著变化。这两种效应的大小取决于接收器/天线配置。在这项研究中发现的调平误差从1.4总电子含量单位（TECU）到5.3 TECU不等。此外，检测到代码延迟接收器IFB的日内变化范围为1.4至8.8 TECU。
The Global Positioning System (GPS) has become a powerful tool for ionospheric studies. In addition, ionospheric corrections are necessary for the augmentation systems required for Global Navigation Satellite Systems (GNSS) use. Dual-frequency carrier-phase and code-delay GPS observations are combined to obtain ionospheric observables related to the slant total electron content (sTEC) along the satellite-receiver line-of-sight (LoS). This observable is affected by inter-frequency biases [IFB; often called differential code biases (DCB)] due to the transmitting and the receiving hardware. These biases must be estimated and eliminated from the data in order to calibrate the experimental sTEC obtained from GPS observations. Based on the analysis of single differences of the ionospheric observations obtained from pairs of co-located dual-frequency GPS receivers, this research addresses two major issues: (1) assessing the errors translated from the code-delay to the carrier-phase ionospheric observable by the so-called levelling process, applied to reduce carrier-phase ambiguities from the data; and (2) assessing the short-term stability of receiver IFB. The conclusions achieved are: (1) the levelled carrier-phase ionospheric observable is affected by a systematic error, produced by code-delay multi-path through the levelling procedure; and (2) receiver IFB may experience significant changes during 1 day. The magnitude of both effects depends on the receiver/antenna configuration. Levelling errors found in this research vary from 1.4 total electron content units (TECU) to 5.3 TECU. In addition, intra-day vaiations of code-delay receiver IFB ranging from 1.4 to 8.8 TECU were detected.