Specular Point Calculation Based on Modified Gradient Descent Algorithm

Global Navigation Satellite System-Reflectometry (GNSS-R) becomes a popular remote-sensing technique for its wide coverage and low cost. GNSS-R works as a bi-static radar receiving weak signals of GNSS satellites reflected from the surface of the Earth. In order to obtain high quality observations, the reflected signals need to be tracked by the open-loop. So the key to the GNSS-R instrument is the calculation of specular point. In this paper, a modified gradient descent algorithm is applied to predict the position of specular point. And an experiment is carried out to test the performance of the algorithm. It turns out that the algorithm has valid results and high real-time performance.