“…To address the aforementioned problems, many improved algorithms for merit function have been proposed, including algorithms based on amplitude constraints [12], system memory coefficients [13], multi-level thresholds [14,15], velocity space partition (VSP) [16,17], velocity space matching (VSM) [18][19][20], high-order DP [21][22][23][24][25], and DP ring (DPR) structure [25]. The introduction of amplitude constraints [12], system memory coefficients [13], and multi-level thresholds [14,15] has a good effect in suppressing the merit function diffusion of strong targets, with a signal-to-noise ratio (SNR) of more than two, but can degrade the detection performance of dim targets.…”