Moving target indication

About: Moving target indication is a research topic. Over the lifetime, 2653 publications have been published within this topic receiving 32435 citations.

Detection and Extraction of Target With Micromotion in Spiky Sea Clutter Via Short-Time Fractional Fourier Transform

Abstract: In order to effectively detect moving targets in heavy sea clutter, the micro-Doppler (m-D) effect is studied and an effective algorithm based on short-time fractional Fourier transform (STFRFT) is proposed for target detection and m-D signal extraction. Firstly, the mathematical model of target with micromotion at sea, including translation and rotation movement, is established, which can be approximated as the sum of linear-frequency-modulated signals within a short time. Then, due to the high-power, time-varying, and target-like properties of sea spikes, which may result in poor detection performance, sea spikes are identified and eliminated before target detection to improve signal-to-clutter ratio (SCR). By taking the absolute amplitude of signals in the best STFRFT domain (STFRFD) as the test statistic, and comparing it with the threshold determined by a constant false alarm rate detector, micromotion target can be declared or not. STFRFT with Gaussian window is employed to provide time-frequency distribution of m-D signals, and the instantaneous frequency of each component can be extracted and estimated precisely by STFRFD filtering. In the end, datasets from the intelligent pixel processing radar with HH and VV polarizations are used to verify the validity of this proposed algorithm. Two shore-based experiments are also conducted using an X-band sea search radar and an S-band sea surveillance radar, respectively. The results demonstrate that the proposed method not only achieves high detection probability in a low-SCR environment but also outperforms the short-time Fourier transform-based method.

Multi-mission multi-mode waveform diversity

Abstract: Previously, the authors presented a novel method for achieving range-dependent beamforming through the use of a frequency diverse array. The frequency diverse array concept was developed using a quasi-stationary waveform assumption. This concept can be extended to non-continuous wave signals for narrowband and wideband applications such as moving target indication (MTI) and synthetic aperture radar (SAR). Alternative implementations are described, which offer the potential for achieving MTI and SAR simultaneously.

A recursive moving-target-indication algorithm for optical image sequences

Abstract: A recursive track-before-detect algorithm, producing potentially large signal-to-noise ratio (SNR) gains under realizable conditions, is described. The basic relation has the form of a linear, constant-coefficient difference equation with a unity magnitude damping factor. Known as recursive moving-target-indication (RMTI), this procedure adapts easily to digital processing and achieves SNR gains comparable to those from other robust track-before-detect algorithms. Examples are given to demonstrate the performance of the moving target indicator (MTI) procedure. >

Reconnaissance with ultra wideband UHF synthetic aperture radar

Abstract: The author addresses the problem of detecting and identifying stationary and moving targets with foliage penetrating UHF synthetic aperture radar (SAR). The role of a target's coherent SAR signature, which varies with the radar's frequency and aspect angle, in forming the Fourier space of the SAR signal is analyzed. The resultant relationship is the basis of an algorithm which, after extracting (digital spotlighting) the target's coherent SAR signature in the reconstruction domain, could be used to differentiate man-made structures from foliage. Methods for blind-velocity moving target indication are discussed. The main tool of the work is a signal theory based analysis of SAR signal via Fourier transform. However, the theory is at most as good as the collected SAR data. >

Range Ambiguous Clutter Suppression for Airborne FDA-STAP Radar

Abstract: Airborne radar arrays oriented toward any direction other than sidelooking cause the range dependence of clutter. It is difficult to handle this range dependence problem in the presence of range ambiguity. Frequency diverse array (FDA) employs a small frequency increment across the array elements, which induces the spatial frequency variant with respect to slant range. Thus, it provides extra degrees-of-freedom in range domain. In this paper, a novel framework of space-time adaptive processing (STAP) radar is established with FDA as the transmit array. In the FDA-STAP radar, the range ambiguous clutter can be discriminated in spatial frequency domain. This is due to the fact that the spatial frequencies of the clutters from different slant ranges are distinguishable even though the range ambiguous clutter is within the same range bin. Simultaneously, the FDA-STAP radar induces secondary range dependence of clutter. To alleviate the secondary range dependence of clutter, a secondary range dependence compensation (SRDC) method is proposed for two cases: 1) the target is assumed in the unambiguous range region and 2) the target is assumed in the ambiguous range region. After the range ambiguous clutter is separated in the spatial frequency domain by using the proposed SRDC method, the traditional clutter compensation approach is applied to further align the spectrum distribution of clutter. Our simulation results demonstrate the superiority of the proposed approach in clutter suppression under range ambiguous clutter scenarios.