Ambiguity-Free Doppler Spectrum Estimation for Inter-Pulse Staggered Waveforms

For an airborne low-pulse repetition frequency (PRF) pulse-Doppler (PD) radar, a single-coherent-processing-interval (CPI) Doppler ambiguity resolution method based on inter-pulse staggered waveforms is proposed to shorten the dwell time required for a fixed surveillance sector. First, a slow-time echo model for the inter-pulse staggered waveform is established, and the mechanism of clutter leakage under generalized correlation filtering is analyzed. Then, an adaptive Doppler processing method based on the minimum variance distortionless response (MVDR) criterion is presented. To address the problem of limited training samples for covariance matrix estimation in airborne scenarios, an iterative adaptive processing method is further proposed to reduce the dependence on a large number of homogeneous training samples. Finally, to reduce the computational complexity, a low-dimensional Doppler subspace is constructed by exploiting prior clutter distribution information, and a reduced-dimension processing scheme is developed. Simulation results show that the proposed method can effectively suppress folded clutter leakage and improve the performance of ambiguity-free Doppler spectrum estimation in strong clutter backgrounds.