Global navigation satellite system-reflectometry (GNSS-R) has great potential to be a novel technique for altimetry, which can be used to derive sea surface heights (SSH). Shipborne altimetry is an important method to measure local SSH with high spatial resolution. In order to test the feasibility of shipborne dual-antenna GNSS-R reflector height retrieval, we developed a GNSS-R receiver system and performed experiments on a research vessel. In this study, direct and reflected GPS/BDS signals were collected using the same setup, and processed to estimate the reflector heights on the basis of path-delay measurements. A strategy of obtaining the GPS/BDS code-level path delay based on 10-ms coherent integration waveforms was adopted. We analyzed the relationship between the path-delay error and the error of the estimated reflector height, and we pointed out that the error in the path delay was amplified when the satellite elevation was low. We also performed reflector height retrieval based on BDS-3 signals for the first time. We evaluated the precisions of the BDS-R and GPS-R derived reflector heights with 30° and 50° cut-off elevations. The results show that the standard deviation of solutions at different cases is around 1.0 m and precisions are slightly better for a 50° cut-off angle compared with a 30° cut-off angle. In general, the mean values of different cases are close, with differences of several centimeters for the experiments.

中文翻译：

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使用双天线反射计系统进行 GPS/BDS 码延迟测量的船载实验

全球导航卫星系统反射计 (GNSS-R) 具有成为测高新技术的巨大潜力，可用于推导海面高度 (SSH)。船载测高仪是测量具有高空间分辨率的本地 SSH 的重要方法。为了测试船载双天线GNSS-R反射器高度反演的可行性，我们开发了GNSS-R接收系统并在研究船上进行了实验。在这项研究中，使用相同的设置收集直接和反射 GPS/BDS 信号，并根据路径延迟测量进行处理以估计反射器高度。采用基于10ms相干积分波形获取GPS/BDS码级路径延迟的策略。我们分析了路径延迟误差与估计反射面高度误差之间的关系，我们指出，当卫星仰角较低时，路径延迟的误差会被放大。我们还首次基于北斗三号信号进行了反射面高度反演。我们评估了 BDS-R 和 GPS-R 导出的反射器高度在 30° 和 50° 截止仰角下的精度。结果表明，不同情况下解的标准偏差约为 1.0 m，与 30° 截止角相比，50° 截止角的精度略好。一般情况下，不同情况的平均值比较接近，实验的差异有几厘米。我们评估了 BDS-R 和 GPS-R 导出的反射器高度在 30° 和 50° 截止仰角下的精度。结果表明，不同情况下解的标准偏差约为 1.0 m，与 30° 截止角相比，50° 截止角的精度略好。一般情况下，不同情况的平均值比较接近，实验的差异有几厘米。我们评估了 BDS-R 和 GPS-R 导出的反射器高度在 30° 和 50° 截止仰角下的精度。结果表明，不同情况下解的标准偏差约为 1.0 m，与 30° 截止角相比，50° 截止角的精度略好。一般情况下，不同情况的平均值比较接近，实验的差异有几厘米。