IET Radar, Sonar & Navigation
Volume 12, Issue 6, June 2018
Volumes & issues:
Volume 12, Issue 6
June 2018
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- Author(s): Yan Wang ; Yuliang He ; Sibo Sun ; Jin Fu
- Source: IET Radar, Sonar & Navigation, Volume 12, Issue 6, p. 585 –592
- DOI: 10.1049/iet-rsn.2017.0586
- Type: Article
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p.
585
–592
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Mismatched filter (MMF) is a commonly used technique to suppress the masking effect of weak targets due to the range sidelobes of stronger targets. Although the existing design of MMFs is proved to have a good performance for radar, they cannot be directly applied to sonar, since the Doppler effect for sonar is far more severe than that for radar. In this study, the authors propose a novel two-dimensional (2D) optimal design of MMFs with a controllable maximum loss for sonar. First, they investigate the design of MMFs based on the 2D cross-correlation function when considering the Doppler effect. It is capable of improving the suppression performance of range sidelobes caused by Doppler signals. MMFs are extended to two dimensions. Then, the optimisation problems to minimise the integrated sidelobe level or the peak sidelobe level are established. It has the capability to flexibly control the maximum loss of signal-to-noise ratio and the 2D MMF characteristics by weighted functions. Finally, the constrained optimisation problems can be solved by transforming into the second-order cone programming problems. Simulations relative to multiple signals (P4 polyphase code, binary m-sequence and chirp signal) prove the validity of the design approach.
- Author(s): Himanshu Maurya and Rajib Kumar Panigrahi
- Source: IET Radar, Sonar & Navigation, Volume 12, Issue 6, p. 593 –602
- DOI: 10.1049/iet-rsn.2017.0581
- Type: Article
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p.
593
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This study presents a hybrid technique for polarimetric synthetic aperture radar (PolSAR) data decomposition. The proposed technique aims to overcome the negative power problem of model-based decomposition methods. To achieve this, matrix rotation theory is used along with hybrid scattering models. The matrix rotation theory is utilised on the basis of underlying dominant scatterer to remove maximal of the cross-polarisation power generated by the coupling between orthogonal states of polarisation. Removing the coupling energy between orthogonal states not only optimised the PolSAR coherency matrix but also transform it more close to reflection symmetry condition. The applicability of the proposed approach is shown through the implementation of hybrid three- and four-component decomposition methods. The proposed hybrid methods are experimentally verified on C-band Radarsat-2 San Francisco and L-band UAVSAR Hayward datasets. For further analysis, different land-cover patches are selected. Moreover, the variations in percentage of negative power pixels are investigated by employing different volume scattering models. Comparative analyses are presented with existing PolSAR decomposition techniques in terms of normalised scattering power means and amount of negative power pixels. All experimental analyses clearly report the superiority of the proposed hybrid approach through improvements over existing PolSAR decomposition techniques along with non-negative scattering powers.
- Author(s): Malcolm Rollason and David Salmond
- Source: IET Radar, Sonar & Navigation, Volume 12, Issue 6, p. 603 –609
- DOI: 10.1049/iet-rsn.2017.0483
- Type: Article
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p.
603
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Track-before-detect methods operate directly upon raw sensor signals without a separate, explicit detection stage. An efficient implementation of a Bayesian track-before-detect particle filter is described for tracking of a single target in a sequence of images. The filter produces a sample-based representation of the probability density function of the target state from raw pixel levels. An indication of the probability that the target is present is also provided. Spatial differentiation of the pixel array data allows objects to be tracked when viewed against a general scene with additive noise. Simulated results illustrate that a dim point target of unknown amplitude, which has become spatially blurred, may be tracked through a sequence of structured images. Detection sensitivity is established using simulated results. The novel aspect of the work is the efficient implementation – in particular, the calculation of the probability of the target being present.
- Author(s): Shengyuan Li ; Nan Liu ; Linrang Zhang ; Juan Zhang ; Shiyang Tang ; Xiang Huang
- Source: IET Radar, Sonar & Navigation, Volume 12, Issue 6, p. 610 –616
- DOI: 10.1049/iet-rsn.2017.0386
- Type: Article
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610
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In multiple-input multiple-output (MIMO) radar settings, it is often desired to transmit power only to a given location or sets of locations defined by the beampattern. Some previous works achieve transmit beampattern synthesis by developing new MIMO radar architectures. In these radar architectures, orthogonal waveforms must be utilised. In fact, the perfect orthogonal waveforms are hardly achievable so that the radar performance loss is inevitable. On the other hand, some waveform design methods, which show superior performance, are proposed. However, the modulus variation and high computational complexity impede their applications in reality. In this study, a simple method for transmit beampattern synthesis is proposed. Based on the circulating code principle, the beampattern synthesis problem has been simplified as a single waveform spectral shaping issue. To solve the spectral shaping issue, an extended circulating code (ECC) with constant modulus is provided. The proposed ECC can achieve an arbitrary beampattern with a single constant modulus waveform while the computational complexity is relatively low. Due to these properties, ECC is simple to apply in practice. The method is evaluated by simulated data and the results can verify its effectiveness.
- Author(s): Geun-Ho Park ; Dong-Gyu Kim ; Ho Jae Kim ; Hyoung-Nam Kim
- Source: IET Radar, Sonar & Navigation, Volume 12, Issue 6, p. 617 –625
- DOI: 10.1049/iet-rsn.2017.0419
- Type: Article
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p.
617
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Frequency-modulation-based (FM-based) passive coherent location (PCL) systems can estimate the target location/velocity by exploiting a single FM channel. In order to improve the performance of PCL systems, multi-channel-single-transmitter setup-based PCL systems have been studied recently. However, it has not yet been considered for direction of arrival estimation based on the multi-channel configuration. Thus, the authors propose a maximum-likelihood angle estimator exploiting the multiple FM-radio channels and derive the Cramer-Rao bound for verifying the convergence of the proposed method in the sense of root-mean-square error (RMSE). In addition, they propose a target association algorithm for solving the ambiguity problem in selecting the steering vectors of each target. Computer simulations are included to show the estimation performance of the proposed method and to compare the RMSE of the single-channel case with that of the multi-channel case.
- Author(s): Tongxin Liu ; Yaogai Hu ; Guobin Yang ; Zhengyu Zhao ; Lan Zhang ; Xiongbin Wu ; Chunhua Jiang
- Source: IET Radar, Sonar & Navigation, Volume 12, Issue 6, p. 626 –631
- DOI: 10.1049/iet-rsn.2017.0427
- Type: Article
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626
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High-frequency (HF) hybrid sky-surface-wave radar (SWR) is very useful for sea-state extraction, and the rich content echo information is very meaningful. On the basis of the multiple-input–multiple-output technology, a new HF hybrid sky-SWR system is designed. The radar transmits multi-frequency signals and synchronously receives the echoes through multiple channels. By adding linear phase shift between frames of the frequency-modulated interrupted continuous wave, the multi-frequency echo signals can be separated in the Doppler spectrum after two fast Fourier transforms. It expanded the HF hybrid sky-SWR from the single-frequency mode to a simultaneous multi-frequency one. Through this system, the ocean dynamics parameters at different frequencies can be simultaneously obtained. Moreover, multi-angle information can be obtained to use for the inversion of the sea surface current and its temporal and spatial variations. Since the transmitter site and the receiver site of the radar are placed in different areas but synchronously work with multiple channels, it is very universal and convenient for network configuration and extension. As validated by the ocean exploration experiment, this system is feasible and reliable.
- Author(s): Zhe Geng ; Renhui Xu ; Hai Deng ; Braham Himed
- Source: IET Radar, Sonar & Navigation, Volume 12, Issue 6, p. 632 –640
- DOI: 10.1049/iet-rsn.2017.0405
- Type: Article
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p.
632
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A joint radar-communication (JRC) system with both radar sensing and communication abilities is proposed to improve spectrum utilisation efficiency. The transmitter of the JRC consists of multiple antenna subarrays transmitting orthogonal waveforms. If the communication receivers are in radar sidelobe directions, the communication data symbols are embedded in the magnitude ratio as well as the phase shift between transmit waveform pairs. In the case of the communication receivers in radar main lobe direction, the data symbols are embedded in the phase shift between transmit waveform pairs only to preserve optimum radar target detection performance. Novel symbol mapping constellation scheme is designed to achieve a high data transmission rate while maintaining a relatively low symbol error rate. The simulation results show that with medium pulse repetition frequency radar waveforms used, the data transmission rate of the proposed JRC system is in the range of Mbits/s.
- Author(s): Qiang Guo ; Liangang Qi ; Jianhong Xiang ; Guoqing Ruan
- Source: IET Radar, Sonar & Navigation, Volume 12, Issue 6, p. 641 –648
- DOI: 10.1049/iet-rsn.2017.0410
- Type: Article
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p.
641
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The number of wide-band interfering signals which can be suppressed by an antenna array is limited to the number of antenna elements. To address this problem, a multiple interferences suppression method based on adaptive signal data regrouping for global navigation satellite system (GNSS) receivers is proposed on the basis of analysing the generalised periodic and sparse property of the wide-band periodic frequency modulated (WBPFM) signals. By exploiting the feature of the singular value ratio (SVR) spectrum of received signals containing periodic components, the authors introduce an improved SVR-based period estimation method to estimate the minimum common period (MCP) of WBPFM interfering signals. Regroup the signal data to construct space–time (ST) matrixes according to the estimated MCP. Then, an orthogonal minimum power distortionless response-based ST processor is adopted to nullify the interferences and protect GNSS signals. Simulation results show that the proposed method can suppress more wide-band interferences without increasing the number of antenna elements.
- Author(s): Tang Bo ; Bai Jian ; Sheng Xin-Qing
- Source: IET Radar, Sonar & Navigation, Volume 12, Issue 6, p. 649 –653
- DOI: 10.1049/iet-rsn.2017.0502
- Type: Article
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649
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This article studies the scattering of the orbital-angular-momentum (OAM) carrying wave by chaff clouds. The OAM-carrying wave (vortex wave) has different phase distribution and amplitude distribution from the plane wave, thus the scattering characteristics of vortex wave by chaff clouds need to be investigated. There are three aspects studied through analysis and numerical computation here, including the scattering by a single dipole, the transmitted wave through the chaff clouds, and the back-scattering by chaff clouds. The results show that the transmitted wave is not an ideal vortex wave any more after transmitting through the chaff clouds, but the information carried by vortex wave can more easily pass through the chaff cloud than plane wave. The reason is that the information is located on the azimuth-angle domain (OAM modes) besides the time domain and the frequency domain. So, the information can be detected by OAM-mode filtering. It may also be beneficial for the application of the vortex wave in chaff jamming.
- Author(s): Qian Meng ; Jian-Ye Liu ; Qing-Hua Zeng ; Shao-Jun Feng ; Rui Xu
- Source: IET Radar, Sonar & Navigation, Volume 12, Issue 6, p. 654 –662
- DOI: 10.1049/iet-rsn.2017.0589
- Type: Article
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p.
654
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Modulation with high-rate Neumann–Hoffman (NH) code in BeiDou signals increases the complexity and calculation load in acquisition as the data bit transitions are more frequent and there is no pilot component for synchronisation which is used in other constellations. Among the current state of the art, double block zero padding (DBZP) method has great potential in reducing the calculation. However, traditional DBZP is very sensitive to bit transition and the misalignment of bit edge will cause serious power loss. To relieve the calculation load and acquire the weak signal successfully, an efficient BeiDou DBZP-based scheme is proposed. The proposed scheme is optimised in two aspects: the NH code phase searching and correlation integration. The step size of the proposed NH code searching method is half an NH code bit which means the number of searches in one navigation message bit is only 40 and the computation load can be reduced greatly. Additionally, the proposed inherited correlation integration establishes a tight inherited structure between adjoining coherent integrations which can reduce the calculation burden further. The experiment results show that the proposed scheme can acquire as weak as 22 dBHz with only about 12% computation time of the traditional DBZP method.
- Author(s): Chen Gang ; Wang Jun ; Guo Shuai ; Wang Jue ; Su Siyuan
- Source: IET Radar, Sonar & Navigation, Volume 12, Issue 6, p. 663 –670
- DOI: 10.1049/iet-rsn.2017.0476
- Type: Article
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663
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This study examines the problem of solving the Doppler ambiguity in analogue television (ATV)-based passive bistatic radar. When mismatched filtering is used to deal with the range ambiguity at 19.2 km, the Doppler ambiguity caused by the 50 Hz field frequency is equally rising because of the signal-to-noise ratio (SNR) loss in the main lobe. Aiming at this problem, an improved mismatched filtering algorithm is proposed. In this new algorithm, the Doppler ambiguity sidelobe suppressing is considered into the cost function, and the mismatched filtering factor is acquired based on minimising the SNR loss, the range sidelobes energy and the Doppler sidelobes energy. Moreover, a batch version is applied to lower the computation. Then the performance of the improved mismatched filtering algorithm is verified by the theoretical analysis. Finally, the application of real data proved the effectiveness of the improved algorithm.
- Author(s): Xiaodong Li ; Changjun Yu ; Fulin Su ; Taifan Quan ; Xiaoliang Chu ; Shuyao Wang
- Source: IET Radar, Sonar & Navigation, Volume 12, Issue 6, p. 671 –677
- DOI: 10.1049/iet-rsn.2018.0044
- Type: Article
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p.
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High-frequency surface wave radar (HFSWR) systems are usually located on the coast and measure electromagnetic backscatter from the sea in the 3–30 MHz band. Based on the theory of ground wave propagation, the detection distance of a low-frequency HFSWR system could be longer that of a high-frequency one. Therefore, a low-frequency HFSWR system is more suitable to extract the significant wave height at a distance. The Barrick's algorithm-based significant wave height extraction method is widely used, and the accuracy of the method has been validated by a large number of experiments. However, it is important to note that under the low sea state, the wave conditions of the data recorded by a low-frequency HFSWR system may not satisfy the wave height condition required in Barrick's algorithm. Hence, the algorithm may produce unreliable results. To address this issue, a method based on Barrick's algorithm, a new non-linear model, and the radial basis function neural network is proposed. Simulations on real-world data collected on the coast of the Tianjin from 1 May 2015 to 25 May 2015 support the method developed.
2D optimal MMF design with a controllable maximum loss for Doppler signals
Non-negative scattering power decomposition for PolSAR data interpretation
Particle filter for track-before-detect of a target with unknown amplitude viewed against a structured scene
Transmit beampattern synthesis for MIMO radar using extended circulating code
Maximum-likelihood angle estimator for multi-channel FM-radio-based passive coherent location
HF hybrid sky-SWR system based on MIMO technology
Fusion of radar sensing and wireless communications by embedding communication signals into the radar transmit waveform
Multiple interferences suppression method based on adaptive signal data regrouping for GNSS receivers
Orbital-angular-momentum-carrying wave scattering by the chaff clouds
Efficient BeiDou DBZP-based weak signal acquisition scheme for software-defined receiver
Improved mismatched filtering for ATV-based passive bistatic radar
Significant wave height extraction using a low-frequency HFSWR system under low sea state
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