Range/Doppler migrations, which result from the integration time increasing and the target's manoeuvring motion, will affect the coherent integration performance severely. To deal with range/Doppler migration, a novel coherent integration algorithm, improved axis rotation discrete chirp‐Fourier transform (IAR‐DCFT), is proposed. IAR‐DCFT could eliminate range migration via improved axis rotation transform, and realise the compensation of Doppler migration and coherent integration via discrete chirp‐Fourier transform. IAR‐DCFT may be regarded as tri‐dimensional motion parameter filter banks, which is analogous to moving target detection that can be treated as Doppler filter banks, and estimate a target's velocity, acceleration and jerk simultaneously. Then the derivations of maximum‐likelihood estimator and likelihood ratio test detector show that IAR‐DCFT is the optimal estimator and a detector. The performance of the optimal estimator is verified by comparing with Cramer‐Rao lower bound. Subsequently, the detailed performance analyses of IAR‐DCFT are provided, including coherent integration gain, coherent integration time, multi‐target detection and computational complexity. Furthermore, the authors introduce the generalisation of IAR‐DCFT, that is, multi‐range‐cell associated IAR‐DCFT (MR‐IAR‐DCFT), which can be applied to detect a target with high‐manoeuvring motion or used in a longer time integration case. Finally, some numerical experiments are given to verify the performance of IAR‐DCFT and MR‐IAR‐DCFT.

This paper presents a novel algorithm for the localization of mixed far-field sources (FFSs) and near-field sources (NFSs) without estimating the source number. Firstly, the algorithm decouples the direction-of-arrival (DOA) estimation from the range estimation by exploiting fourth-order spatial-temporal cumulants of the observed data. Based on the joint diagonalization structure of multiple spatial-temporal cumulant matrices, a new one-dimensional (1-D) spatial spectrum function is derived to generate the DOA estimates of both FFSs and NFSs. Then, the FFSs and NFSs are identified and the range parameters of NFSs are determined via beamforming technique. Compared with traditional mixed sources localization algorithms, the proposed algorithm avoids the performance deterioration induced by erroneous source number estimation. Furthermore, it has a higher resolution capability and improves the estimation accuracy. Computer simulations are implemented to verify the effectiveness of the proposed algorithm.

With the increasing of aircraft target speed and the decreasing of radar cross-section (RCS), conventional radar systems have been unable to meet the needs of modern target detection. Due to the characteristics of bistatic radar transmitting and receiving, the weak targets can be detected by using the scattering in different directions of the target compared with monostatic radar. Meanwhile, range migration and Doppler migration will occur when the target with a constant speed is observed for a long time. Therefore, this paper applies the second-order keystone transform (SOKT) to the bistatic radar, which based on the keystone transform (KT). This method is mainly aimed at solving the problems of range migration and Doppler migration of bistatic radar systems which occur during the long-term coherent integration process, and proving its effectiveness through theoretical analysis and simulation experiments.