Axis rotation MTD algorithm for weak target detection

A novel coherent integration algorithm, improved axis rotation fractional Fourier transform (IAR-FRFT), is proposed to detect the weak targets with a constant radial acceleration. IAR-FRFT could eliminate the linear range migration and alleviate the nonlinear range migration via an improved axis rotation transform and realize coherent integration via fractional Fourier transform. Numerical experiments verify the performance of IAR-FRFT on four aspects: coherent integration time, coherent integration gain, computational complexity, and multitarget detection.

Detection of constant radial acceleration weak target via IAR-FRFT

Because of the high speed and the long repeat interval of the radar, there would be serious echo envelope migration while using low-PRF narrowband chirp radar to detect weak high speed targets. The coherent integration method of envelope migration compensation based on keystone transform is studied, the problem of Doppler ambiguity is analyzed, and the influence on the coherent integration effect of Doppler ambiguity degree error and signal band width is simulated, which helps to determine the step of Doppler ambiguity degree search step. The algorithm is introduced and finally experiments on real data are made to testify the algorithm. The results of 128 echo pulses procession show that the SNR could be enhanced by 6 dB, which confirm the effectiveness of this method and improve the ability of weak high speed target detection.

Application research of keystone transform in weak high-speed target detection in low-PRF narrowband Chirp radar

Fast rotating targets such as gimbaled antennas or propeller blades may cause migration through resolution cells (MTRC) of the high-resolution range profile during the imaging time, which makes the inverse synthetic aperture radar image smeared. To solve this problem, a novel imaging method for fast rotating targets is proposed in this paper. The method is based on the segmental pseudo Keystone transform, which is designed to realize MTRC correction. The fast realization is achieved by employing the discrete match Fourier transform, which makes the algorithm feasible and simple. Experiments with simulated radar data demonstrate the performance of the proposed method.

A Novel Imaging Method for Fast Rotating Targets Based on the Segmental Pseudo Keystone Transform

In radar detection, weak targets’ range migration often happens during long time integration. To detect weak targets effectively, an improved axis rotation moving target detection (IAR-MTD) is introduced and analysed in detail. IAR-MTD can detect weak targets by compensating the linear part of range migration via the axis rotation and coherently integrating the echoes via moving target detection (MTD). Then the realization of IAR-MTD is derived. Furthermore, the coherent integration gain of IAR-MTD is analysed, which is better than that of traditional MTD, Radon–Fourier transform (RFT) and Keystone transform (KT). Subsequently, to decrease the computational complexity of IAR-MTD, some suggestions are given. Besides, unambiguous Doppler estimation, the tolerance of acceleration, and the multi-target detection of IAR-MTD are analysed respectively. Finally, some numerical experiments are provided to show the performance of IAR-MTD in different conditions and testify the advantages of IAR-MTD over MTD, RFT and KT. The result indicates that IAR-MTD may effectively detect the weak moving targets with constant radial velocity and it is compatible with MTD radar system.

Improved axis rotation MTD algorithm and its analysis

The improvement of the capability to detect moving target with very small radar signature is usually realized by long term accumulation.According to the design principle of conventional PD(Pulse Doppler) radar,target's range migration can't exceed half of the range resolution cell in coherent integration time,which means that the accumulation time is restrained by target's motion.For high range resolution radar or the radar system focusing on the detection of fast moving targets,such a restriction is difficult to satisfy.In this paper,a novel motion compensation method based on keystone transform is presented,which can correct range migration without the exact value of target velocity,and as a result,make the accumulation time free of the restriction due to target motion.

Zeng Tao

Papers

Weak Target Detection Based on Keystone Transform