多模多频GNSS-IR水位反演中的频间偏差分析及改正

doi:10.11947/j.AGCS.2022.20210461

摘要/Abstract

摘要： 准确的水位监测对于水资源调控、水灾监控及气候气象研究十分重要。近年来,随着全球导航卫星系统的不断发展,一种GNSS干涉遥感水位反演技术被提出。目前,GNSS-IR水位反演中主要有3类误差:高度变化误差、高度角弯曲误差和对流层延迟误差,相关的改正方法也被陆续提出。本文研究了4个GNSS跟踪站(HKQT、SW50、SW51和SW52)的多模多频反演结果,发现除了已经发现的3类误差外,还存在一种明显的频间偏差。现有研究对于GNSS-IR频间偏差的研究很少,尚未达成将其归为GNSS-IR误差源的共识。为了进一步挖掘频间偏差的特性、加深对该误差的认识,本文计算了不同信号的有效高度(reflector height,RH),发现不同频率信号的RH反演值间存在差距;将该差距与波长进行对比分析,发现该差距与信号波长存在显著的线性关系(相关系数>95%)。该偏差量级在分米级,表现出了明显的频间偏差系统特性。针对发现的频间偏差及其相关特性,本文提出了相关的误差改正方法,结果表明:顾及频间偏差的改正结果比未顾及频间偏差的反演结果的均方根误差高1.5~12 cm。同时,改正后的融合反演值的精度较未改正的独立信号的反演值提高了30%~80%;精度的提高得益于多模多频信号提供的大量冗余数据以及对各类误差(包括系统误差、粗差和随机误差)的正确处理。

关键词: GNSS-IR, 水位反演, 频间偏差, 误差改正

Abstract: Accurate water level monitoring is very important for water resources regulation, flood monitoring, and climate and meteorological research. In recent years, with the continuous development of GNSS, one technique named GNSS-interferometry reflectometry (GNSS-IR) water level retrieval has been proposed. Currently, three types of errors—height variation error, elevation bending error and tropospheric delay error have been discovered, and related correction methods have also been proposed. After analysis of the multi-mode and multi-frequency retrievals of four GNSS stations (HKQT, SW50, SW51 and SW52), this paper found that there is also an obvious inter-frequency bias in retrievals in addition to the three types of errors. Previous research has few studies on GNSS-IR inter-frequency bias, and there is no consensus that it is classified as a GNSS-IR error source. In order to further dig out the characteristics of the inter-frequency bias and deepen the understanding of this error, this paper calculated the reflector height (RH) of different signals, and found that there were deviations between the RH values of different frequency signals. Comparing these deviations with the corresponding wavelengths, we found that these deviations have a significant linear relationship with the signal wavelengths (correlation coefficient>95%). The magnitude of these deviations were in a decimeter level, which showed system characteristics of obvious inter-frequency bias. Based on the characteristics of the inter-frequency bias, this paper proposed an error correction method. The results showed that root mean squared errors (RMSEs) of the correction retrievals with consideration of the inter-frequency deviation were 1.5 to 12 cm higher than these without consideration. And the accuracy of the corrected combined retrievals was 30%~80% higher than the retrievals of the uncorrected individual signals. The improvement of accuracy benefits from the large amount of redundant data provided by the multi-mode and multi-frequency signals and the correct handling of various errors including systematic errors, gross errors and random errors.

Key words: GNSS-IR, water level retrieval, inter-frequency bias, error correction

中图分类号:

P227

王笑蕾, 何秀凤, 宋敏峰, 陈殊, 牛紫瑾. 多模多频GNSS-IR水位反演中的频间偏差分析及改正[J]. 测绘学报, 2022, 51(11): 2328-2338.

WANG Xiaolei, HE Xiufeng, SONG Minfeng, CHEN Shu, NIU Zijin. Analysis of inter-frequency bias in multi-mode multi-frequency GNSS-IR water level retrieval and correction method[J]. Acta Geodaetica et Cartographica Sinica, 2022, 51(11): 2328-2338.

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