Efficient Coherent Integration Detection for Space-Moving Target With Complex Azimuth Doppler Ambiguity

The space-moving target (SMT) poses a great challenge for coherent integration detection because of the across range cell (ARC) and Doppler frequency broadening (DFB) induced by the relative motions between SMT and radar platform. Moreover, the intricate azimuth Doppler ambiguity complicates the coherent integration of SMT. To tackle these challenges, a proficient method for the coherent integration of SMT detection under complex azimuth Doppler ambiguity is introduced. First, a modified second-order keystone transform (MSoKT) operation based on the new deramp function with regulatory factor is presented to address the quadratic ARC (QARC) and Doppler spectrum ambiguity. Second, the linear ARC (LARC) is eliminated by the proposed novel processing procedure based on the improved range frequency reversal transform (IRFRT) and modified 2-D scaled Fourier transform (2DSCFT) without searching of Doppler ambiguity number. Third, the DFB is removed by the 1-D scaled Fourier transform (1DSCFT) with minimal computational overhead. After that, the well-focused result of SMT is obtained. The proposed method demonstrates computational efficiency, as its implementation involves only the fast Fourier transform (FFT) and complex multiplication operations, while also eliminating the need to search for Doppler ambiguity numbers. The presented method exhibits robustness against complex azimuth Doppler ambiguity and can effectively address the ambiguous speed sidelobe (ASSL). The multitarget scenario is further investigated, and a strategy for identifying spurious peaks caused by cross terms is proposed. Real data results are provided to validate the method's performance in scenarios involving both single and multiple targets.