The Precise Point Positioning (PPP) with fast integer ambiguity resolution (PPP-RTK) is feasible only if the solution is augmented with precise ionospheric parameters. The vertical ionospheric delays together with the receiver hardware biases, are estimated simultaneously based on the uncombined PPP model. The performance of the ionospheric delays was evaluated and applied in the PPP-RTK demonstration during the low solar activity period. The processing was supported by precise products provided by Deutsches GeoForschungsZentrum Potsdam (GFZ) and also by real-time products provided by the National Centre for Space Studies (CNES). Since GFZ provides only precise orbits and clocks, other products needed for ambiguity resolution, such as phase biases, were estimated at the Geodetic Observatory Pecny (GOP). When ambiguity parameters were resolved as integer values in the GPS-only solution, the initial convergence period was reduced from 30 and 20 min to 24 and 13 min when using CNES and GFZ/GOP products, respectively. The accuracy of ionospheric delays derived from the ambiguity fixed PPP, and the CODE global ionosphere map were then assessed. Comparison of ambiguity fixed ionospheric delay obtained at two collocated stations indicated the accuracy of 0.15 TECU for different scenarios with more than 60% improvement compared to the ambiguity float PPP. However, a daily periodic variation can be observed from the multi-day short-baseline ionospheric residuals. The accuracy of the interpolated ionospheric delay from global maps revealed a dependency on the location of the stations, ranging from 1 to 3 TECU. Precise ionospheric delays derived from the EUREF permanent network with an inter-station distance larger than 73 km were selected for ionospheric modeling at the user location. Results indicated that the PPP ambiguity resolution could be achieved within three minutes. After enlarging the inter-station distance to 209 km, ambiguity resolution could also be achieved within several minutes.

中文翻译：

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多尺度参考网络电离层延迟的准确性评估及其在低太阳活动期间对 PPP 的增强

具有快速整数模糊度分辨率 (PPP-RTK) 的精确点定位 (PPP) 只有在解决方案增加了精确的电离层参数时才可行。垂直电离层延迟和接收器硬件偏差是基于未组合的 PPP 模型同时估计的。在低太阳活动期间，电离层延迟的性能被评估并应用于 PPP-RTK 演示。Deutsches GeoForschungsZentrum Potsdam (GFZ) 提供的精确产品以及国家空间研究中心 (CNES) 提供的实时产品支持该处理。由于 GFZ 仅提供精确的轨道和时钟，因此大地测量观测站 Pecny (GOP) 估计了模糊度解决所需的其他产品，例如相位偏差。当在仅 GPS 解决方案中将模糊度参数解析为整数值时，使用 CNES 和 GFZ/GOP 产品时，初始收敛周期分别从 30 和 20 分钟减少到 24 和 13 分钟。然后评估了由模糊度固定 PPP 和 CODE 全球电离层图得出的电离层延迟的准确性。在两个并置站获得的模糊度固定电离层延迟的比较表明，与模糊度浮动 PPP 相比，不同场景的准确度为 0.15 TECU，提高了 60% 以上。然而，可以从多日短基线电离层残差中观察到每日周期性变化。来自全球地图的内插电离层延迟的准确性揭示了对站点位置的依赖性，范围从 1 到 3 TECU。从站间距离大于 73 公里的 EUREF 永久网络得出的精确电离层延迟被选择用于用户位置的电离层建模。结果表明，PPP模糊度解决可以在三分钟内实现。将站间距离扩大到209公里后，也可以在几分钟内实现模糊解决。