Fast-Moving Target Detection With Frequency Diverse Element-Pulse Coding Radar

This article investigates the detection of fast-moving targets in a frequency diverse (FD) element-pulse coding (EPC) radar. At the modeling stage, the nonoverlapping linear frequency modulation waveforms are transmitted, and the wide spatial coverage is obtained by applying a bandwidth-level frequency offset (FO) across the adjacent transmit elements. In addition, the EPC factor is utilized to distinguish different transmit pulses. At the receiver, the received echo is first processed through a bank of FO-dependent matched filters, which is followed by a decoding procedure to separate the transmitted waveforms and to extract echoes from different range ambiguous regions. Then, for the subsequent moving target detection, a modified keystone transform is performed to correct the linear range migration resulted from fast movement of the target. In addition, a compensation procedure is designed to eliminate the incoherence between echoes from different transmit elements, which is resulted from frequency diversity. Furthermore, in order to achieve high range resolution corresponding to the overall transmit bandwidth, a spectrum splicing method based on 2-D beamforming is proposed, where the angle and range ambiguity index are estimated in the joint transmit–receive domain based on maximum likelihood, and the weight vector is constructed. Finally, coherent processing in the Doppler domain is implemented for the spliced echo to focus the target. Numerical results are provided to verify the effectiveness of the proposed method for detecting the fast-moving target within the FD-EPC architecture.