A Parameter Estimation Method for Sub-Nyquist Sampled Radar Signals Based on Frequency-domain Delay-Doppler Two-dimensional Focusing

In the problem of sub-Nyquist sampled pulse Doppler radar signals, the existing methods have poor anti-noise performance, and the subsequent parameter estimation in the sequential parameter estimation methods is seriously affected by the accuracy of the previous parameter estimation. A Frequency-domain Delay-Doppler Two-dimensional Focusing (FD2TF) algorithm is proposed based on Finite Rate of Innovation (FRI) sampling method to solve the problem. The algorithm can obtain a series of Fourier coefficients of the signal at a sampling rate lower than the Nyquist sampling frequency through the FRI sampling structure. The time delay and Doppler parameters can be estimated simultaneously through the frequency- domain two-dimensional focusing process, and the problem of error accumulation in parameter sequential estimation methods can be avoided. Theoretical analysis proves that the algorithm can greatly improve the signal-to-noise ratio of the sampled signal, and improve the anti-noise performance and robustness of the algorithm. This paper also proposes a two-dimensional focusing simplification algorithm based on inverse Fourier transform, which greatly reduces the computational complexity of the two- dimensional focusing algorithm while increasing the grid density of parameter estimation. Simulation and comparative experiment results show that the proposed method is effective and has good anti-noise performance.