Coherent Integration Algorithm for a Maneuvering Target With High-Order Range Migration

Abstract

This paper considers the coherent integration problem for a maneuvering target with complex motions, where the velocity, acceleration and jerk result in respectively the first-order range migration (FRM), second-order range migration (SRM) and third-order range migration (TRM) within the coherent pulse interval. A new coherent integration algorithm based on generalized keystone transform (KT) and secondorder dechirp process is proposed, which employs the third-order KT, six-order KT, second-order KT and fold factor searching to correct the TRM, SRM and FRM, respectively. The range migration change during each step and computational complexity are also theoretically analyzed. Compared with the generalized Radon Fourier transform (GRFT) algorithm, the presented method can avoid the blind speed sidelobe (BSSL) and acquire close integration performance but with much lower computational cost. Simulations are provided to demonstrate the effectiveness. Finally, a generalized method, named generalized KT and generalized dechirp process (GKTGDP), is also introduced for the maneuvering target with arbitrary high-order range migration.Maneuvering target, coherent integration, third-order range migration, generalized keystone transform, range migration correction.1053-587X (c) , IEEE Transactions on Signal Processing 3 for coherent integration due to the TRM. The generalized Radon Fourier transform (GRFT) was then presented to remove the TRM and conduct the coherent integration processing [15], [21]. Although GRFT can obtain coherent accumulation via jointly searching in target's motion parameter space, it has two limitations. Firstly, because of discrete pulse sampling, finite range resolution and limited integration time, the blind speed sidelobe (BSSL) may inevitably appear in the GRFT output, which leads to serious false alarm and detection performance deterioration [22]. A BSSL suppression method, based on the minimum operator of two weighted GRFT outputs, was studied in [22]. Nevertheless, it requires to bisect the coherent integration period, thus the integration performance would be decreased by about 3 dB.Secondly, the GRFT method is often computationally prohibitive, since it involves the solution of a fourdimensional searching. An improved particle swarm optimization (PSO) was then introduced to reduce the computational burden of GRFT [23]. However, the PSO may sensitive to the initial parameters set and get trapped in the local optimization for the scenario of multiple targets. This paper considers the coherent integration problem for a maneuvering target with jerk motion, involving TRM, SRM and FRM within the coherent pulse interval. A new coherent integration method based on generalized KT and second-order dechirp process (SDP) is proposed, where the third-order KT, six-order KT, second-order KT and fold factor searching are respectively employed to remove the TRM, SRM and FRM. After that, cross range Fourier transform (FT) is carried out to achieve the coherent accumulation of target energy. We also theoretica...

A Novel Detection Method Based on Generalized Keystone Transform and RFT for High-Speed Maneuvering Target

“…Figure 3(a) shows the result after the third-order KT, six-order KT and phase term compensation .By figure 3(a), it is observed that the total range migration value is 60 and it is reduced by 3. In theory, the RM change in this step is [4] ΔR ≈ a 1 T 3 + a 0 T 2 + 1 2 v 0 T Δr = 3 , where the Result of RFT range walk value corresponding to the unambiguous velocity is v 0 T /Δr ≈ −2 (minus denotes the direction of range walk opposite to the direction of target motion).Therefore, the simulation result is consistent with the theoretical result and TRM and SRM are eliminated.By the de-chirping method, the estimated acceleration is 409.40m s 2 , the estimated jerk is 271.52m s 3 . After GKT, the integration is realized by RFT.The result of RFT is given by Figure 3(b).It is seen that the target can be detected, where the estimated range is18000m,the estimated velocity is 1450m/s.…”

“…Therefore, the velocity of target can be expressed as [4] v 1 = v 0 + Γv amb (6) Where v amb denotes the blind velocity, which is computed by v amb = P RF ·λ…”

“…In order to compensate for the cubic and quadratic phase term, the improved de-chirping process technique is used to estimate the radial jerk and acceleration. Since the processes of third-order KT, Six-order KT and compensating the high-order phase factor have been analyzed in [4] in detail, the result would be given directly.…”

“…Let N, N r , N v , N a0 , N a1 denote the number of echo pulses, range sampling cells, searching velocity and searching acceleration, searching jerk, respectively. As to the Third-order KT, estimating the radial jerk, cubic phase term compensation, Six-order KT, estimating the radial acceleration and quadratic phase term compensation, 1 2 [4].For the RFT, 1 2 NN r log 2 (N r ) +N r N v N multiplications and NN r log 2 (N r ) + N r N v (N − 1) additions are needed. To make comparison with GRFT [8], the detailed computational complexity of the proposed method and GRFT is given in Table I.…”

“…With the development of the phased array antennas technique, the digital beam forming (DBF) technique has been widely used to obtain a long illumination time for radars [3]. However, With the increasing of the time for radar coherent integration, the motions of maneuvering targets are complex, e.g., high velocity, acceleration and jerk, which would result in the FRM,SRM and TRM [4]. Therefore, RM correction is a key procedure in maneuvering target detection, which result in serious performance loss when achieving the coherent integration.…”