Separation of Overlapped Direct and Reflected Waveforms for Low-Altitude UAV-Based GNSS-R Altimetry. - Xu, Ziyin; Wang, Xianyi; Xia, Junming; Sun, Yueqiang; Liu, Cheng; Wang, Zhuoyan; Tian, Yusen; Qiu, Tongsheng; Wang, Dongwei (Remote Sensing, 2026)