基于相关功率修正的地基GNSS-R土壤湿度反演

利用全球导航卫星系统反射信号测量技术(GNSS-R)进行土壤湿度反演过程中，实际接收天线方向性会造成GNSS直反信号相关功率测量偏差。针对地基观测场景下天线方向性造成的相关功率的类余弦振荡问题，提出了基于多项式拟合的信号相关功率修正方法。为了验证所提方法的有效性，开展了地基GNSS-R土壤湿度观测实验，结果表明:基于多项式拟合的相关功率修正可以消除信号相关功率的类余弦振荡，提升GNSS-R土壤湿度反演中的观测数据有效性和反演结果准确性。 

Ground-based GNSS-R soil moisture retrieval based on correlation power correction

In soil moisture observation using Global Navigation Satellite System Reflectometry (GNSS-R) technique, actual antennas' directionalities will bring about the biases in the correlation power measurements of the direct and reflected GNSS signals. For eliminating the cosine-like oscillatory bias of the correlation power caused by antenna directionality in ground-based scenario, this paper proposes a correlation power correction method based on the polynomial fitting. In order to verify the validity of this method, the ground-based GNSS-R soil moisture observation experiment is carried out. The experimental results show that the correlation power correction using polynomial fitting can remove the cosine-like oscillation of the correlation power waveform, and then improve the efficiency of measurement data and the accuracy of retrieval results.