“…9 For targets with complex motion, in which rotational motion may cause higher-order phase terms, the traditional LFM signal model is not appropriate. 21,22 However, after compensating the third-order term with the estimated parameter, the LPWD algorithm estimates the secondorder coefficient using CPF method, which does lead to the heavy computational burden due to the Fourier transform with respect to the nonuniformly spaced data. [10][11][12][13][14] With regard to the parameter estimation of CPS, numerous algorithms, including the cubic phase function (CPF), 15,16 the higher-order ambiguity function, 17 the product generalized CPF (PGCPF), 18 the product high-order matched-phase transform, 19 and the modified version of CPF (MCPF), 14 have been addressed, but all of them involve multilinear transformation and discrete Fourier transform for the nonuniformly spaced signal sample, which result in extensive crossterms under multi-CPSs and undesirable computational complexity.…”