基于无几何电离层滤波模型的北斗三号系统相位周跳与中断修复方法

高精度位置服务依赖模糊度正确固定的载波相位观测值,而复杂环境的相位周跳和中断给模糊度固定和数据处理带来了巨大挑战。北斗三号系统向全球播发四频和五频信号,为提升周跳处理性能提供了机遇。本文建立了探测多频超宽巷周跳的伪距-相位无几何组合模型,以及探测窄巷周跳的相位-相位无几何组合模型,并以周跳探测成功概率最大为准则确定了多频最优超宽巷和窄巷组合。由于电离层延迟制约了数据中断和电离层变化剧烈情况下的窄巷周跳探测,进而建立了顾及电离层延迟的窄巷周跳探测滤波模型。试验结果表明,对30 s采样间隔,基于无几何组合模型探测周跳的成功率均优于96%;对于3 min的数据中断,基于无几何组合模型的周跳探测成功率仅为70%,但补偿电离层延迟的滤波模型将成功率提升至95%以上。

BDS-3 cycle slip and data gap repair based on the geometry-free ionosphere-filter model

High-accurate positioning service relies on carrier phase observations with ambiguities correctly fixed. However, the cycle slips and data gaps caused by environment complexity enhance the challenges for ambiguity resolution and data processing. BDS-3 system broadcasts the quad- and penta-frequency signals all over the world, providing an opportunity to improve the performance of cycle slip processing. Firstly, we establish the pseudorange-to-phase and phase-to-phase geometry-free combination models to detect the extra-wide-lane (EWL) and narrow-lane (NL) cycle slips, respectively. With maximizing the success rate of cycle slips detection, the optimal EWL and NL combinations are determined. Since the ionospheric delay is the key to limit the detection of NL cycle slip and data gap in case of active ionospheric situation, a filtering model with assimilating the ionospheric effects is then developed. The experiment results show as follows. For the sampling interval of 30 s, the geometry-free based model can obtain the success rate as large as 96% for both EWL and NL cycle slip detection. While for the data gap of 3 min, the geometry-free based NL cycle slip detection can only achieve the success rate of 70%, but it can be improved to larger than 95% by the ionospheric delay compensated filtering model.