Two-stage method for joint time delay and Doppler shift estimation

The focus of this research is to provide a fast and precise method for joint time delay and Doppler shift estimation. The main procedure is divided into two stages. In the first stage, the pre-weighted Zoom fast Fourier transform and quadratic surface fitting methods are used for fast computing the ambiguity function and the for coarse estimation, respectively. In the second stage, the values near the coarse estimates are calculated and quadratic surface fitting method is used again for fine estimation. The two-stage method reduces the computational load without losing the precision. Simulation and experimental results are used to demonstrate the effectiveness of the proposed method.