基于DDMR辅助的GNSS-R载波相位差测高方法

提出了一种基于时延-多普勒映射接收机（DDMR，Delay-Doppler Map Receiver）辅助的载波相位差提取方法，给出了系统结构及信号处理方法.该方法将DDMR中所观测到的码相位差作为直射信号与反射信号的码相位延时量，将完成跟踪的直射信号扩频码进行对应的延时用于完成对反射信号的开环码跟踪.该方法省去了码相位延时搜索的过程，且可以准确地对反射信号扩频码进行同步.为了验证系统的可行性及实际性能，进行了针对水面高度测量的岸基试验并给出了试验结果.岸基试验证明采用该方法的GNSS-R（Global Navigation Satellite System Reflection）接收机可以稳定地对反射信号进行跟踪并提取直射与反射信号的载波相位差，测高精度约为2.5 cm，经过0.5 s的数据平均后精度可达0.6 cm.

Carrier phase difference estimation method based on DDMR-assistance for GNSS-R altimetry

A carrier phase difference estimation method based on the delay-Doppler map receiver (DDMR)-assistance for (GNSS-R) coastal altimetry was proposed. The system structure and the signal processing method were given. The proposed method, which can avoid the complicated search for the GNSS spreading codes, uses the code phase difference observed from DDMR as the estimated time-delay between the spreading codes of the direct signal and the reflected signal, and then delays the tracked codes of the direct signal to achieve the open-loop tracking of the reflected signal. Field experiments with real coastal receivers demonstrate the effectiveness of this method, which can steadily track the weak reflected signal and accurately extract the difference of the carrier phase. The experiment results show that the altimetry accuracy is about 2.5 cm without data average or 0.6 cm with 0.5 s average.