Xiongjun Fu

A Nearest Neighbor Fuzzy Classifier for Radar Target Recognition Using Combined Features

This paper presents a nearest neighbor fuzzy classifier (NNFC), which is very suitable to process the combined features with different data types and scales. The NNFC does not require the combined features with the same data types and scales, and it is not necessary to perform any pre-processing. It uses the fuzzy membership function to process each feature of the combined features. Experiments with real satellite data show that the NNFC can effectively perform radar target recognition of multiple features combination

Sequential Separation of Radar Target Micro-Motions Based on IRT

A micro-motion sequential separation method based on inverse Radon transform (IRT) is proposed. The method has an accumulation effect and, therefore can adapt to environment with relatively low signal-to-noise ratio (SNR). This method has the capability of antidiscontinuous tracking and thus is suitable in the multi-target tracking scenario. The method is a good candidate in large dynamic range scenes to detect relatively weak scatterers of micro-motions. It is more computationally efficient in comparison with the methods based on the Hough transform (HT).

Space object identification based on narrowband radar cross section

A space object identification method based on narrowband radar cross section (RCS) is proposed in this paper. With RCS sequences, statistical features are extracted, the two-dimensional sizes of the object are estimated by adopting an improved size estimation model (SEM) and the attitude stability of the object is determined by periodicity analysis. Feature templates are constructed in matrix form with those three kinds of features of the training sample set and especially when constructing the template for a large number of statistical features, dynamic fuzzy clustering technology is used. The k-nearest neighbor fuzzy classifier is adopted to accomplish the identification. At the end, experiments with the measured data are conducted to confirm the effectiveness of the method.

Inverse synthetic aperture radar imaging and cross-range scaling for space objects

Radar imaging based on theorem of inverse synthetic aperture is an important means for space object identification, and cross-range scaling is a key issue. This paper makes a systematic overview on the theorem of ISAR imaging, and then presents the relationship between the observation time and ISAR image cross-range resolution of space objects. An accurate crossrange scaling method for ISAR image of space objects is proposed. Outdoor experiment of ISAR imaging and cross-range scaling for space object show the effectivity of the method.

Channel isolation and range sidelobe suppression for instantaneous full-polarization radar

Polarization is quite useful for target detection and identification since it is an intrinsic property of targets. The real polarization scattering matrix (PSM) namely Sinclair scattering matrix must be acquired by instantaneous full polarization measurements. For the requirement of full polarization measurement to radar targets instantaneously, a solution to the two key issues on channel isolation and sidelobe suppression is proposed here from the perspective of waveform design and echo processing. The required waveform characteristics for instantaneous full polarization radar and the demands of sidelobe suppression performance were reviewed. Channel isolation is guaranteed by orthogonal Waveform Design, and the performance of auto-correlation and Doppler tolerance is obtained at the same time. A novel signal transmission guideline is designed based on comprehensive utilization of positive and negative chirp rate linear frequency-modulation (LFM) waveform and orthogonal phase-coded waveform hopping pulse to pulse randomly. Effective sidelobe reduction is achieved by inter-pulse information processing. Whats more, the signal-to-noise ratio (SNR) and the performance of low probability of intercept radar are improved simultaneously.

Design and implementation of the digital radio frequency memory system based on advanced extensible interface 4.0

Digital radio frequency memory (DRFM) is an important part of modern electronic jamming equipment. It achieves high fidelity in the storage of radar waveform and guarantees the coherence between interference and radar signal. In this paper, a design scheme of the DRFM system based on FPGA and DSP is proposed, and the FPGA is the vital part of it. According to the complex FPGA function and high design challenge, an architecture based on advanced extensible interface 4.0 (AXI4) used to build the embedded system on FPGA is presented, which greatly enhances the flexibility of the system, speeds up the development, and brings conveniences for upgrade and maintenance.

Optimal waveform synthesis for adaptive radar

Targets echoes from different radar transmitted waveforms can provide different target signatures.. As for adaptive radar, the transmitted waveforms are adaptive to the operational environment to acquire optimal performance. This paper presents a waveform synthesis method for adaptive radar based on a cascade of the water-filling algorithm and iterative least squares (LS) approach. The optimal energy spectrum density (ESD) of the synthesized waveform is obtained by the water-filling algorithm based on maximizing the mutual information (MI) criterion; the echo can then extract the maximum amount of target information. The iterative LS approach is used to synthesize the complex-valued waveform in time domain while the modulus of synthesized waveform remains constant, which is helpful for maintaining the transmitter efficiency. Simulation results show that the proposed optimal waveform synthesis method is competent for adaptive radar.

The anti-jamming method based on front-back-edge tracking of VGPO jamming

Tracking radar can provide the range, velocity and angle measured values of the target continuously, smoothly and accurately. Velocity gate pull off (VGPO) jamming is an active deception jamming aiming at velocity automatic tracking system. The system of Pulse Doppler (PD) tracking radar may face VGPO jamming, so a new method of anti-jamming is proposed in this paper. First of all, it judges the jamming towing direction from the velocity gate moving acceleration, then tracks the target velocity using front-back-edge tracking method in Doppler domain. Using the front-edge tracking method counters jamming while jamming is posterior to the target echo, and using the back-edge tracking method counters the jamming while jamming is in front of target echo. The simulation results show that this method has good effectiveness of anti-VGPO jamming.

Anti-jamming technology of dense co-frequency synchronous range false targets

The co-frequency synchronous range false target deception jamming based on digital radio frequency memory is able to form stable tracks, which causing the radar to track the false target and be under great threat. In view of pulse system range tracking radar, this paper proposes a new scheme of the inter-frame multiplicative non-coherent processing which counters the co-frequency synchronous range false target deception jamming with the pulse repetition period (PRT) agility. Radar system sends random PRT agility, and makes the responder synchronous false targets change into asynchronous false targets after entering the radar receiver, and then suppresses jamming by inter-frame multiplicative non-coherent accumulation. This method rejects the dense co-frequency synchronous range false targets jamming which can form stable tracks effectively, which has been approved by the simulation results.

Bi-static inverse synthetic aperture radar imaging for space objects

For the purpose of improving the utilization rate and detection capability of space surveillance radar, a meaningful Implementation of bi-static inverse synthetic aperture radar (ISAR) is proposed. Bi-static ISAR imaging is helpful to extract the shape and size information of objects from different perspectives. The ability of anti-jamming, anti-stealthy and target recognition will be increased owing to bi-static imaging. The particularity of bi-static ISAR imaging is analyzed, followed by imaging simulation. An effective bi-static ISAR system is constructed including a wideband mono-static radar, a wideband receiver, and an accessional facility which performs signal acquisition, storage and processing. Outfield experiments of space objects observation were carried out and two-dimensional bi-static ISAR images were obtained successfully.