He Zishu

Modified Hough Transform for Searching Radar Detection

In this letter, we propose a modified Hough transform (HT) algorithm for radar detection by shifting the parameter space cells as well as exploiting the phase information of signal. The proposed modified HT brings (1) significant improvement of radar target detection at low signal-to-noise ratios and (2) complexity reduction of HT implementation in radar detection applications compared to the conventional HT-based methods. Simulation results are presented showing the performance gain obtained by the proposed modified HT over the conventional methods.

Maximum Likelihood DOA Estimation Using Particle Swarm Optimization Algorithm

Direction-of-arrival (DOA) estimation is an important problem. Many algorithms have been proposed. The maximum likelihood (ML) is one of the good solutions. This paper presents an application of particle swarm optimization (PSO) developed for obtaining the global optimal solution of ML DOA estimation. It overcomes the local optima problem existing in some ML DOA estimation algorithms and improves the estimation accuracy. The computation complexity is modest

The parameter setting problem of signal OFDM-LFM for MIMO radar

Multiple Input Multiple Output (MIMO) radar is a new radar technique, which transmits orthogonal signal at the transmitter and forms wide beam. In this paper, we select the orthogonal frequency division multi LFM signal as the orthogonal waveform. In this model, the bandwidth of single LFM and the frequency interval are important. Only the situation of equi-interval frequency is studied here. Assume the bandwidth is fixed, the selection of frequency interval affects not only the range resolution and processing speed, but also other performance of radar. In this paper, we investigate the relationship of the two parameters, also the concepts of range sidelobe are introduced. Then we demonstrated the random initial phase can suppress the second-class sidelobe. In the end, we draw the conclusion that by appropriate parameter setting, the OFDM-LFM waveform can has good performance in MIMO radar.

Dwell scheduling algorithm for multifunction phased array radars based on the scheduling gain

A real-time dwell scheduling model, which takes the time and energy constraints into account is founded from the viewpoint of scheduling gain. Scheduling design is turned into a nonlinear programming procedure. The real-time dwell scheduling algorithm based on the scheduling gain is presented with the help of two heuristic rules. The simulation results demonstrate that compared with the conventional adaptive scheduling method, the algorithm proposed not only increases the scheduling gain and the time utility but also decreases the task drop rate.

Sidelobe Reduction of Linear Nonuniformly Spaced Arrays

This paper describes a modified genetic algorithm (MGA) for optimizing the performance of linear sparse arrays with a fixed current distribution. Under the design constraints of the number of elements, the aperture and the minimum element spacing, the MGA has been utilized to optimize the element position to reduce the peak sidelobe level (PSLL) of the sparse arrays. Unlike standard GA using unalterable corresponding relationship between the gene variables and their coding, the MGA employs the coding resetting of gene variables to avoid infeasible solution throughout the GA evolutionary process. And the proposed approach has reduced the size of the searching area of the GA by means of indirect description of individuals. The process of MGA and the simulated results confirming the great efficiency of this algorithm are provided in this paper

A beamforming method for cylindrical array based on synthetic pattern of subarray

A new approach to beamforming for a cylindrical conformal array geometry is developed. We first derive a deterministic expression that describes the beam pattern of arbitrary weighted cylindrical conformal array. Then, we derive the beamformer for uniform linear array (ULA) of directional antennas. Thus, the pattern of subarray is synthesized, and we design the method which uses beamformer for ULA of the synthetic pattern. To demonstrate the validity of the method, 2× 4 and 2×8 cylinder arrays are constructed and experimental results agree well with theoretical expectations.

Ionospheric decontamination for skywave OTH radar based on complex energy detector

For over-the-horizon (OTH) radar, the ocean clutter is very strong. And this becomes a big challenge for the target detection. The clutter suppression is a very important procedure for the OTH radar. For the skywave OTH radar, the radar signal will propagate through the ionosphere. This will cause a contamination due to its unstable movement. Then the Bragg frequencies will be smeared and clutter spectrum will spread wider rather than a single line spectra. This smear will cause the target more difficult to be detected and even buried in clutter. Compensation is necessary to cancel the ionospheric effect. This article proposes the clutter decontamination algorithm based on the complex energy detector (CED). The energy detector (ED) is originally proposed to demodulate the real AM–FM signals. The ED is expanded to complex domain. After the expansion, there is no mutual coupling between the amplitude and frequency component for an AM–FM signal. The phase of the Bragg clutter return contaminated by the ionosphere is modeled by a frequency-modulated signal, while its magnitude is amplitude modulated. The CED algorithm is applied to track the instantaneous frequency of the contaminated return signal, which is then used for compensation. Simulation results are presented. The simulation results show that, comparing with the Hankel rank reduction algorithm, the proposed algorithm has better performance under the situation of large frequency fluctuation.For over-the-horizon (OTH) radar, the ocean clutter is very strong. And this becomes a big challenge for the target detection. The clutter suppression is a very important procedure for the OTH radar. For the skywave OTH radar, the radar signal will propagate through the ionosphere. This will cause a contamination due to its unstable movement. Then the Bragg frequencies will be smeared and clutter spectrum will spread wider rather than a single line spectra. This smear will cause the target more difficult to be detected and even buried in clutter. Compensation is necessary to cancel the ionospheric effect. This article proposes the clutter decontamination algorithm based on the complex energy detector (CED). The energy detector (ED) is originally proposed to demodulate the real AM–FM signals. The ED is expanded to complex domain. After the expansion, there is no mutual coupling between the amplitude and frequency component for an AM–FM signal. The phase of the Bragg clutter return contaminated by the ionosphere is modeled by a frequency-modulated signal, while its magnitude is amplitude modulated. The CED algorithm is applied to track the instantaneous frequency of the contaminated return signal, which is then used for compensation. Simulation results are presented. The simulation results show that, comparing with the Hankel rank reduction algorithm, the proposed algorithm has better performance under the situation of large frequency fluctuation.

Receiving Signal Processing of MIMO Radar Based On Transmitting Diversity

Multiple input multiple output (MIMO) radar is a new emerging radar technique developed recently. The principle of MIMO radar based on transmitting diversity is described and the method of receiving signal processing also is presented. Simulation results show that the proposed receiving signal processing method can simultaneously form multiple receive beams and surveillance multiple targets. It also can improve Doppler resolution

A recursive method for compensating ionospheric phase contamination based on multistage Taylor expansion

A recursive approach for the compensation of the ionospheric phase contamination is proposed based on multistage Taylor expansion and the extended Kalman filter. The proposed algorithm can dynamically compensate the ionospheric phase contamination. We show by numerical examples that the proposed algorithm outperformances the conventional methods such as the polynomial phase signal (PPS) and the singular value decomposition (SVD).

Joint TOA-based range estimation in target motion analysis

When the time of arrival (TOA) of the periodic signal is used, the range and velocity of the target are observable in target motion analysis. The each range on any one of a set of positions can be estimated for the constant-speed target through using more than three measurements of the TOA. This paper presents a joint range estimation algorithm to realize all range estimations of a set of target positions. For a set of target positions along trajectory, the paper firstly analyses the closed-form range-velocity least-square solution for the single position (SPLS), then proposes the all position joint range-velocity least-square solution (APLS), and finally validates the following conclusions with simulation results: the estimation precision of range and velocity on each position in SPLS algorithm is different from each other; the estimation precision of APLS algorithm is better than that of the SPLS algorithm on the most positions, and all the estimation precisions on a set of target positions are roughly equal.