Topic Editors

Electronic and Communication Institute, China Three Gorges University, Yichang 443002, China
Dr. Wei Liu
Department of Electronic and Electrical Engineering, The University of Sheffield, Sheffield S102TN, UK
Dr. Jin He
School of Electronic Information and Electrical Engineering, Shanghai Jiao Tong University, Shanghai 200240, China
Dr. Veerendra Dakulagi
Department of Electronics & Communication Engineering, Guru Nanak Dev Engineering College, Bidar, Karnataka, India

Advances in Array Signal Processing with Errors: Models, Algorithms and Applications

Abstract submission deadline
closed (30 April 2023)
Manuscript submission deadline
closed (30 June 2023)
Viewed by
74736

Topic Information

Dear Colleagues,

Sensor array plays a crucial role in remote sensing. In recent decades, extensive efforts have been devoted to array signal processing. Most of the existing works only consider the ideal signal model, e.g., well-calibrated sensors, approximate signal model, known source number, white Gaussian noise. Unfortunately, errors always exist in actual remote sensing scenarios, for instance, imperfect waveform, gain-phase error, mutual coupling, hybrid-field sources, and coloured noise. In the presence of errors, model mismatch can occur between the practical signal model and the ideal one and yields decreased performance.

This Topic is intended to solicit high-quality contributions in error calibration for remote sensing. Authors are invited to submit original papers presenting new theoretical and/or application-oriented research including models, algorithms, and applications. Additionally, review papers on these topics are also welcome. Topics of interest include but are not limited to:

  • Remote sensing with imperfect waveform;
  • Remote sensing with advanced signal sampling;
  • Remote sensing with sensor position errors;
  • Remote sensing with gain-phase errors;
  • Remote sensing with sensor mutual coupling;
  • Array signal processing with a far-field, near-field, and hybrid-field source;
  • Array signal processing with non-Gaussian noise;
  • Array signal processing with coherent sources.

Dr. Fangqing Wen
Dr. Wei Liu
Dr. Jin He
Dr. Veerendra Dakulagi
Topic Editors

Keywords

  • remote sensing
  • array signal processing
  • array calibration
  • coherent source
  • hybrid-field source
  • non-Gaussian noise

Participating Journals

Journal Name Impact Factor CiteScore Launched Year First Decision (median) APC
Remote Sensing
remotesensing
4.2 8.3 2009 23 Days CHF 2700
Sensors
sensors
3.4 7.3 2001 17 Days CHF 2600
Applied Sciences
applsci
2.5 5.3 2011 16.9 Days CHF 2400
Technologies
technologies
4.2 6.7 2013 19.7 Days CHF 1600
Electronics
electronics
2.6 5.3 2012 15.6 Days CHF 2400

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Published Papers (41 papers)

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15 pages, 3931 KiB  
Communication
An Enhanced Spatial Smoothing Technique of Coherent DOA Estimation with Moving Coprime Array
by Meng Yang, Yu Zhang, Yuxin Sun and Xiaofei Zhang
Sensors 2023, 23(19), 8048; https://doi.org/10.3390/s23198048 - 23 Sep 2023
Cited by 1 | Viewed by 1049
Abstract
This paper investigates the direction of arrival (DOA) estimation of coherent signals with a moving coprime array (MCA). Spatial smoothing techniques are often used to deal with the covariance matrix of coherent signals, but they cannot be used in sparse arrays. Therefore, super-resolution [...] Read more.
This paper investigates the direction of arrival (DOA) estimation of coherent signals with a moving coprime array (MCA). Spatial smoothing techniques are often used to deal with the covariance matrix of coherent signals, but they cannot be used in sparse arrays. Therefore, super-resolution algorithms such as multiple signal classification (MUSIC) cannot be applied in the DOA estimation of coherent signals in sparse arrays. In this study, we propose an enhanced spatial smoothing method specifically designed for MCA. Firstly, we combine the signals received by the MCA at different times, which can be regarded as a sparse array with a larger number of array sensors. Secondly, we describe how to compute the covariance matrix, derive the signal subspace by eigenvalue decomposition, and prove that the signal subspace is also equivalent to a received signal. Thirdly, we apply enhanced spatial smoothing to the signal subspace and construct a rank recovered covariance matrix. Finally, the DOA of coherent signals are well estimated by the MUSIC algorithm. The simulation results validate the improved performance of the proposed algorithm compared with traditional methods, particularly in scenarios with low signal-to-noise ratios. Full article
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13 pages, 19436 KiB  
Communication
Improved Amplitude-Phase Calibration Method of Nonlinear Array for Wide-Beam High-Frequency Surface Wave Radar
by Wei Fu, Han Liu, Zhihui Chen, Shu Yang, Yuandong Hu and Fangqing Wen
Remote Sens. 2023, 15(18), 4405; https://doi.org/10.3390/rs15184405 - 7 Sep 2023
Cited by 1 | Viewed by 868
Abstract
The amplitude and phase errors in array elements lead to uncertainties in the estimation of arrival angles (DOA), which, in turn, affect the accuracy of current measurements for high-frequency surface wave radar (HFSWR). To address this issue, this paper proposes a passive amplitude-phase [...] Read more.
The amplitude and phase errors in array elements lead to uncertainties in the estimation of arrival angles (DOA), which, in turn, affect the accuracy of current measurements for high-frequency surface wave radar (HFSWR). To address this issue, this paper proposes a passive amplitude-phase self-calibration method for a wide-beam HFSWR system with a nonlinear array. This method utilizes the aggregation of the amplitude ratio among array elements to screen reception matrices of single DOA sources. Based on the differences in reception matrices, the amplitude error is calibrated. Moreover, the cost function is calculated using the multiple signal classification (MUSIC) algorithm, and the initial phase error is first obtained after triangular array dimensionality reduction. Then, the phase error is further calibrated through quadratic-form iterative optimization. This method has been validated through simulations and real measurements. An approximately 4-day dataset obtained via HFSWR is reanalyzed in this paper. After data calibration, the radar-estimated currents were in good agreement with the buoy-measured results, with a root mean square error (RMSE) as low as 0.06 m/s and a correlation coefficient (CC) of up to 0.88. The results indicate that this method is suitable for the amplitude and phase error calibration of nonlinear arrays in wide-beam HFSWR systems. Full article
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22 pages, 8377 KiB  
Article
A Sage–Husa Prediction Algorithm-Based Approach for Correcting the Hall Sensor Position in DC Brushless Motors
by Lu Wang, Yong Cheng and Wei Yin
Sensors 2023, 23(14), 6604; https://doi.org/10.3390/s23146604 - 22 Jul 2023
Cited by 1 | Viewed by 1227
Abstract
Accurate knowledge of the rotor position is essential for the control of brushless DC motors (BLDCM). Any deviation in this identification can cause fluctuations in motor current and torque, increase noise, and lead to reduced motor efficiency. This paper focused on a BLDCM [...] Read more.
Accurate knowledge of the rotor position is essential for the control of brushless DC motors (BLDCM). Any deviation in this identification can cause fluctuations in motor current and torque, increase noise, and lead to reduced motor efficiency. This paper focused on a BLDCM equipped with a three-phase binary Hall sensor. Based on the principle of minimum deviation, this paper estimated the relative installation offset between the Hall sensors. It also provided a clear method for ideal phase commutation position recognition and eliminated the Hall sensor installation position deviation. The proposed pre-calibration method identified and eliminated the offset of the permanent magnet poles, the delay time caused by the Hall signal conditioning circuit, and the offset of the sensor signal identification due to armature response under different loads. Based on the pre-calibration results, a correction strategy for correcting the rotor position information of BLDCMs was proposed. This paper presented a self-adaptive position information prediction algorithm based on the Sage–Husa method. This filters out rotor position information deviations that are not eliminated in pre-calibration. Experimental results on a hydrogen circulation pump motor showed that, after the pre-calibration method was adopted, the Mean Square Error (MSE) of motor speed fluctuations decreased by 92.0%, motor vibration was significantly reduced, average phase current decreased by 62.8%, and the efficiency of the hydrogen circulation pump system was significantly improved. Compared to the traditional KF prediction algorithm, the Sage–Husa adaptive position information prediction algorithm reduced the speed fluctuation during the uniform speed operation stage and speed adjustment stage, the speed curve overshoot, and the commutation time deviation throughout the process by 44.8%, 56.0%, 54.9%, and 14.7%, respectively. This indicates a higher disturbance rejection ability and a more accurate and stable prediction of the commutation moment. Full article
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21 pages, 10678 KiB  
Article
Near-Field Beamforming Algorithms for UAVs
by Yinan Zhang, Guangxue Wang, Shirui Peng, Yi Leng, Guowen Yu and Bingqie Wang
Sensors 2023, 23(13), 6172; https://doi.org/10.3390/s23136172 - 5 Jul 2023
Cited by 2 | Viewed by 1189
Abstract
This study presents three distributed beamforming algorithms to address the challenges of positioning and signal phase errors in unmanned aerial vehicle (UAV) arrays that hinder effective beamforming. Firstly, the array’s received signal phase error model was analyzed under near-field conditions. In the absence [...] Read more.
This study presents three distributed beamforming algorithms to address the challenges of positioning and signal phase errors in unmanned aerial vehicle (UAV) arrays that hinder effective beamforming. Firstly, the array’s received signal phase error model was analyzed under near-field conditions. In the absence of navigation data, a beamforming algorithm based on the Extended Kalman Filter (EKF) was proposed. In cases where navigation data were available, Taylor expansion was utilized to simplify the model, the non-Gaussian noise of the compensated received signal phase was approximated to Gaussian noise, and the noise covariance matrix in the Kalman Filter (KF) was estimated. Then, a beamforming algorithm based on KF was developed. To further estimate the Gaussian noise distribution of the received signal phase, the noise covariance matrix was iteratively estimated using unscented transformation (UT), and here, a beamforming algorithm based on the Unscented Kalman Filter (UKF) was proposed. The proposed algorithms were validated through simulations, illustrating their ability to suppress the malign effects of errors on near-field UAV array beamforming. This study provides a reference for the implementation of UAV array beamforming under varying conditions. Full article
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15 pages, 499 KiB  
Communication
2D-DOA Estimation in Multipath Using EMVS Rectangle Array
by Zhe Zhang, Lei Zhang, Han Wang and Junpeng Shi
Remote Sens. 2023, 15(13), 3308; https://doi.org/10.3390/rs15133308 - 28 Jun 2023
Viewed by 1013
Abstract
Electromagnetic vector sensor (EMVS) arrays bring an epochal opportunity for direction finding, as they enable the estimation of two-dimensional direction of arrival (2D-DOA) and polarization characteristics. In this paper, we revisit the 2D-DOA estimation problem in an EMVS rectangle array under multipath propagation. [...] Read more.
Electromagnetic vector sensor (EMVS) arrays bring an epochal opportunity for direction finding, as they enable the estimation of two-dimensional direction of arrival (2D-DOA) and polarization characteristics. In this paper, we revisit the 2D-DOA estimation problem in an EMVS rectangle array under multipath propagation. An improved subspace estimator is proposed, which addresses the rank-deficit problem through matrix arrangement, and the 2D-DOA and polarization parameters are estimated via combining the normalized vector cross-product with the least squares method. Our proposed method is suitable for a single snapshot scenario and offers superior accuracy compared to existing methods. To validate its effectiveness, several numerical simulations have been designed and conducted. Full article
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18 pages, 7210 KiB  
Article
A Sparse Shared Aperture Design for Simultaneous Transmit and Receive Arrays with Beam Constraints
by Dujuan Hu, Xizhang Wei, Mingcong Xie and Yanqun Tang
Sensors 2023, 23(12), 5391; https://doi.org/10.3390/s23125391 - 7 Jun 2023
Cited by 1 | Viewed by 1127
Abstract
The utilization of efficient digital self-interference cancellation technology enables the simultaneous transmit and receive (STAR) phased array system to meet most application requirements through STAR capabilities. However, the development of application scenario requirements makes array configuration technology for STAR phased arrays increasingly important. [...] Read more.
The utilization of efficient digital self-interference cancellation technology enables the simultaneous transmit and receive (STAR) phased array system to meet most application requirements through STAR capabilities. However, the development of application scenario requirements makes array configuration technology for STAR phased arrays increasingly important. Thus, this paper proposes a sparse shared aperture STAR reconfigurable phased array design based on beam constraints which are achieved by a genetic algorithm. Firstly, a design scheme for transmit and receive arrays with symmetrical shared apertures is adopted to improve the aperture efficiency of both transmit and receive arrays. Then, on the basis of shared aperture, sparse array design is introduced to further reduce system complexity and hardware costs. Finally, the shape of the transmit and receive arrays is determined by constraining the side lobe level (SLL), main lobe gain, and beam width. The simulated results indicate that the SLL of the transmit and receive patterns under beam-constrained design have been reduced by 4.1 dBi and 7.1 dBi, respectively. The cost of SLL improvement is a reduction in transmit gain, receive gain, and EII of 1.9 dBi, 2.1 dBi, and 3.9 dB, respectively. When the sparsity ratio is greater than 0.78, the SLL suppression effect is also significant, and the attenuation of EII, transmit, and receive gains do not exceed 3 dB and 2 dB, respectively. Overall, the results demonstrate the effectiveness of a sparse shared aperture design based on beam constraints in producing high gain, low SLL, and low-cost transmit and receive arrays. Full article
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13 pages, 4402 KiB  
Communication
Hole-Free Nested Array with Three Sub-ULAs for Direction of Arrival Estimation
by Yule Zhang, Guoping Hu, Hao Zhou, Juan Bai, Chenghong Zhan and Shuhan Guo
Sensors 2023, 23(11), 5214; https://doi.org/10.3390/s23115214 - 30 May 2023
Cited by 1 | Viewed by 1063
Abstract
Sparse arrays are of deep concern due to their ability to identify more sources than the number of sensors, among which the hole-free difference co-array (DCA) with large degrees of freedom (DOFs) is a topic worth discussing. In this paper, we propose a [...] Read more.
Sparse arrays are of deep concern due to their ability to identify more sources than the number of sensors, among which the hole-free difference co-array (DCA) with large degrees of freedom (DOFs) is a topic worth discussing. In this paper, we propose a novel hole-free nested array with three sub-uniform line arrays (NA-TS). The one-dimensional (1D) and two-dimensional (2D) representations demonstrate the detailed configuration of NA-TS, which indicates that both nested array (NA) and improved nested array (INA) are special cases of NA-TS. We subsequently derive the closed-form expressions for the optimal configuration and the available number of DOFs, concluding that the DOFs of NA-TS is a function of the number of sensors and the number of the third sub-ULA. The NA-TS possesses more DOFs than several previously proposed hole-free nested arrays. Finally, the superior direction of arrival (DOA) estimation performance based on the NA-TS is supported by numerical examples. Full article
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16 pages, 1654 KiB  
Article
A Coherent Wideband Acoustic Source Localization Using a Uniform Circular Array
by Meng Jiang, Chibuzo Joseph Nnonyelu, Jan Lundgren, Göran Thungström and Mårten Sjöström
Sensors 2023, 23(11), 5061; https://doi.org/10.3390/s23115061 - 25 May 2023
Cited by 3 | Viewed by 1357
Abstract
In modern applications such as robotics, autonomous vehicles, and speaker localization, the computational power for sound source localization applications can be limited when other functionalities get more complex. In such application fields, there is a need to maintain high localization accuracy for several [...] Read more.
In modern applications such as robotics, autonomous vehicles, and speaker localization, the computational power for sound source localization applications can be limited when other functionalities get more complex. In such application fields, there is a need to maintain high localization accuracy for several sound sources while reducing computational complexity. The array manifold interpolation (AMI) method applied with the Multiple Signal Classification (MUSIC) algorithm enables sound source localization of multiple sources with high accuracy. However, the computational complexity has so far been relatively high. This paper presents a modified AMI for uniform circular array (UCA) that offers reduced computational complexity compared to the original AMI. The complexity reduction is based on the proposed UCA-specific focusing matrix which eliminates the calculation of the Bessel function. The simulation comparison is done with the existing methods of iMUSIC, the Weighted Squared Test of Orthogonality of Projected Subspaces (WS-TOPS), and the original AMI. The experiment result under different scenarios shows that the proposed algorithm outperforms the original AMI method in terms of estimation accuracy and up to a 30% reduction in computation time. An advantage offered by this proposed method is the ability to implement wideband array processing on low-end microprocessors. Full article
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19 pages, 1772 KiB  
Article
Bayesian Noise Modelling for State Estimation of the Spread of COVID-19 in Saudi Arabia with Extended Kalman Filters
by Lamia Alyami, Deepak Kumar Panda and Saptarshi Das
Sensors 2023, 23(10), 4734; https://doi.org/10.3390/s23104734 - 13 May 2023
Cited by 1 | Viewed by 1751
Abstract
The epistemic uncertainty in coronavirus disease (COVID-19) model-based predictions using complex noisy data greatly affects the accuracy of pandemic trend and state estimations. Quantifying the uncertainty of COVID-19 trends caused by different unobserved hidden variables is needed to evaluate the accuracy of the [...] Read more.
The epistemic uncertainty in coronavirus disease (COVID-19) model-based predictions using complex noisy data greatly affects the accuracy of pandemic trend and state estimations. Quantifying the uncertainty of COVID-19 trends caused by different unobserved hidden variables is needed to evaluate the accuracy of the predictions for complex compartmental epidemiological models. A new approach for estimating the measurement noise covariance from real COVID-19 pandemic data has been presented based on the marginal likelihood (Bayesian evidence) for Bayesian model selection of the stochastic part of the Extended Kalman filter (EKF), with a sixth-order nonlinear epidemic model, known as the SEIQRD (Susceptible–Exposed–Infected–Quarantined–Recovered–Dead) compartmental model. This study presents a method for testing the noise covariance in cases of dependence or independence between the infected and death errors, to better understand their impact on the predictive accuracy and reliability of EKF statistical models. The proposed approach is able to reduce the error in the quantity of interest compared to the arbitrarily chosen values in the EKF estimation. Full article
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19 pages, 933 KiB  
Article
1-D and 2-D Direction of Arrival Estimation in a Conical Conformal Array: Design and Implementation
by Hongyun Zhang, Ping Li, Guangwei Zhang, Guolin Li and Xiaofeng Gao
Sensors 2023, 23(9), 4536; https://doi.org/10.3390/s23094536 - 6 May 2023
Viewed by 1287
Abstract
Direction of arrival (DOA) estimation for conformal arrays is challenging due to non-omnidirectional element patterns and shadow effects. Conical conformal array (CCA) can avoid the shadow effect at small elevation angles. So CCA is suitable for DOA estimation on both azimuth and elevation [...] Read more.
Direction of arrival (DOA) estimation for conformal arrays is challenging due to non-omnidirectional element patterns and shadow effects. Conical conformal array (CCA) can avoid the shadow effect at small elevation angles. So CCA is suitable for DOA estimation on both azimuth and elevation angles at small elevation angles. However, the element pattern in CCA cannot be obtained by conventional directional element coordinate transformation. Its local element pattern also has connection with the cone angle. The paper establishes the CCA radiation pattern in local coordinate system using 2-D coordinate transformation. In addition, in the case of large elevation angle, only half elements of the CCA can receive signal due to the shadow effect. The array degrees of freedom (DOF) are reduced by halves. We introduce the difference coarray method, which increases the DOF. Moreover, we propose a more accurate propagator method for 2-D cases. This method constructs a new propagation matrix and reduces the estimation error. In addition, this method reduces computational complexity by using linear computations instead of eigenvalue decomposition (EVD) and avoids spectral search. Simulation and experiment verify the estimation performance of the CCA. Both demonstrate the CCA model established in this paper is corresponding to the designed CCA antenna, and the proposed algorithms meet the needs of CCA angle detection. When the number of array elements is 12, the estimation accuracy is about 5 degrees. Full article
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15 pages, 4221 KiB  
Article
Height Measurement for Meter Wave Polarimetric MIMO Radar with Electrically Long Dipole under Complex Terrain
by Yuwei Song and Guimei Zheng
Remote Sens. 2023, 15(5), 1265; https://doi.org/10.3390/rs15051265 - 24 Feb 2023
Cited by 1 | Viewed by 1491
Abstract
Height measurement of meter wave radar is a difficult and important problem. This paper studies the height measurement of meter wave polarimetric (MWP)-MIMO array radar under complex terrain. The traditional electrically short dipole has low radiation efficiency, and the collocated dipole vector antenna [...] Read more.
Height measurement of meter wave radar is a difficult and important problem. This paper studies the height measurement of meter wave polarimetric (MWP)-MIMO array radar under complex terrain. The traditional electrically short dipole has low radiation efficiency, and the collocated dipole vector antenna has strong mutual coupling. This paper proposes to use electrically long dipoles and separated vector antennae to solve the problems of low radiation efficiency and strong mutual coupling. In addition, different from the traditional flat terrain, the research of this paper is based on the conditions of complex undulating terrain. First, the height measurement signal model of the MWP-MIMO radar with separated electrically long dipole under the complex terrain is derived. Then, a preprocessing method of block orthogonal matching pursuit is proposed to obtain the coarse estimation of the target’s elevation. Then, under the guidance of the coarse estimation, the generalized MUSIC algorithm is used to obtain the high-precision elevation estimation of the target, and then the height measurement of the target is obtained according to the geometric relationship. Finally, the effectiveness of the proposed algorithm is proved by computer simulations. Full article
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16 pages, 8253 KiB  
Article
System Identification Methodology of a Gas Turbine Based on Artificial Recurrent Neural Networks
by Rubén Aquize, Armando Cajahuaringa, José Machuca, David Mauricio and Juan M. Mauricio Villanueva
Sensors 2023, 23(4), 2231; https://doi.org/10.3390/s23042231 - 16 Feb 2023
Cited by 1 | Viewed by 2257
Abstract
The application of identification techniques using artificial intelligence to the gas turbine (GT), whose nonlinear dynamic behavior is difficult to describe through differential equations and the laws of physics, has begun to gain importance for a little more than a decade. NARX (Nonlinear [...] Read more.
The application of identification techniques using artificial intelligence to the gas turbine (GT), whose nonlinear dynamic behavior is difficult to describe through differential equations and the laws of physics, has begun to gain importance for a little more than a decade. NARX (Nonlinear autoregressive network with exogenous inputs) is one of the models used to identify GT because it provides good results. However, existing studies need to show a systematic method to generate robust NARX models that can identify a GT with satisfactory accuracy. In this sense, a systematic method is proposed to design NARX models for identifying a GT, which consists of nine precise steps that go from identifying GT variables to obtaining the optimized NARX model. To validate the method, it was applied to a case study of a 215 MW SIEMENS TG, model SGT6-5000F, using a set of 2305 real-time series data records, obtaining a NARX model with an MSE of 1.945 × 10−5, RMSE of 0.4411% and a MAPE of 0.0643. Full article
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23 pages, 1038 KiB  
Article
Passive Joint Emitter Localization with Sensor Self-Calibration
by Guangbin Zhang, Hengyan Liu, Wei Dai, Tianyao Huang, Yimin Liu and Xiqin Wang
Remote Sens. 2023, 15(3), 671; https://doi.org/10.3390/rs15030671 - 23 Jan 2023
Cited by 1 | Viewed by 1417
Abstract
This paper studies the problem surrounding distributed passive arrays (sensors) locating multiple emitters while performing self-calibration to correct possible errors in the assumed array directions. In our setting, only the angle-of-arrival (AoA) information is available for localization. However, such information may contain bias [...] Read more.
This paper studies the problem surrounding distributed passive arrays (sensors) locating multiple emitters while performing self-calibration to correct possible errors in the assumed array directions. In our setting, only the angle-of-arrival (AoA) information is available for localization. However, such information may contain bias due to array directional errors. Hence, localization requires self-calibration. To achieve both, the key element behind our approach is that the received signals from the same emitter should be geometrically consistent if sensor arrays are successfully calibrated. This leads to our signal model, which is built on a mapping directly from emitter locations and array directional errors to received signals. Then we formulate an atomic norm minimization and use group sparsity to promote geometric consistency and align ‘ghost’ emitter locations from calibration errors. Simulations verify the effectiveness of the proposed scheme. We derive the Cramér Rao lower bound and numerically compare it to the simulations. Furthermore, we derive a necessary condition as a rule of thumb to decide the feasibility of joint localization and calibration. Full article
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11 pages, 377 KiB  
Communication
DOA Estimation in Impulsive Noise Based on FISTA Algorithm
by Jinfeng Zhang, Ping Chu and Bin Liao
Remote Sens. 2023, 15(3), 565; https://doi.org/10.3390/rs15030565 - 17 Jan 2023
Cited by 2 | Viewed by 1545
Abstract
This paper investigates the challenging problem of direction-of-arrival (DOA) estimation in impulsive noise and presents a fast iterative shrinkage-thresholding algorithm (FISTA)-based approach to tackle the difficulty. More specifically, the underlying noise is modelled as the superposition of outliers in the white Gaussian noise. [...] Read more.
This paper investigates the challenging problem of direction-of-arrival (DOA) estimation in impulsive noise and presents a fast iterative shrinkage-thresholding algorithm (FISTA)-based approach to tackle the difficulty. More specifically, the underlying noise is modelled as the superposition of outliers in the white Gaussian noise. Leveraging on the spot-sparse characteristic of the outlier matrix, the FISTA is conducted on each snapshot of the array output. With the estimated outlier matrix and the coarse on-grid DOA estimates, an alternating optimization method is developed to retrieve the final off-grid DOA estimates. Simulation results show that the proposed method outperforms existing methods in terms of resolution capability and estimation accuracy especially in severe noise environments. Full article
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6 pages, 3020 KiB  
Communication
Broadband DOA Estimation by Exploiting DFT Extrapolation
by Euiho Shin, Young-seek Chung, Seonkyo Kim, Cheolsun Park and Jungsuek Oh
Appl. Sci. 2023, 13(1), 660; https://doi.org/10.3390/app13010660 - 3 Jan 2023
Viewed by 1433
Abstract
This study proposes broadband direction (DOA) estimation through discrete Fourier transform (DFT) extrapolation. We used DFT extrapolation in the lower band and extended the sampled data to reduce the beam width in the spectral domain and improved the accuracy of the estimated DOA. [...] Read more.
This study proposes broadband direction (DOA) estimation through discrete Fourier transform (DFT) extrapolation. We used DFT extrapolation in the lower band and extended the sampled data to reduce the beam width in the spectral domain and improved the accuracy of the estimated DOA. The sampled data with a length of 12 were extrapolated to 36 by the addition of 12-element virtual arrays to 12 real arrays on both sides. The average RMSEs of the estimated DOAs were measured throughout the wide frequency band. To verify the validity of the proposed algorithm, we demonstrated that the RMSE obtained from the broadband DOA estimation for multiple signals of interest (SOIs) was reduced in the extrapolated array. It was demonstrated that the proposed algorithm can broaden the frequency band at which a fixed number of array can estimate the DOA accurately. Full article
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21 pages, 4459 KiB  
Article
Fast Target Localization in FMCW-MIMO Radar with Low SNR and Snapshot via Multi-DeepNet
by Yunye Su, Xiang Lan, Jinmei Shi, Lu Sun and Xianpeng Wang
Remote Sens. 2023, 15(1), 66; https://doi.org/10.3390/rs15010066 - 23 Dec 2022
Cited by 2 | Viewed by 2071
Abstract
Frequency modulated continuous wave (FMCW) multiple-input multiple-output (MIMO) radars are widely applied in target localization. However, during the process, the estimation accuracy decreases sharply without considerable signal-to-noise ratio (SNR) and sufficient snapshot number. It is therefore necessary to consider estimation schemes that are [...] Read more.
Frequency modulated continuous wave (FMCW) multiple-input multiple-output (MIMO) radars are widely applied in target localization. However, during the process, the estimation accuracy decreases sharply without considerable signal-to-noise ratio (SNR) and sufficient snapshot number. It is therefore necessary to consider estimation schemes that are valid under low signal-to-noise ratio (SNR) and snapshot. In this paper, a fast target localization framework based on multiple deep neural networks named Multi-DeepNet is proposed. In the scheme, multiple interoperating deep networks are employed to achieve accurate target localization in harsh environments. Firstly, we designed a coarse estimate using deep learning to determine the interval where the angle is located. Then, multiple neural networks are designed to realize accurate estimation. After that, the range estimation is determined. Finally, angles and ranges are matched by comparing the Frobenius norm. Simulations and experiments are conducted to verify the efficiency and accuracy of the proposed framework. Full article
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14 pages, 2094 KiB  
Article
Self-Calibration for Sparse Uniform Linear Arrays with Unknown Direction-Dependent Sensor Phase by Deploying an Individual Standard Sensor
by Long Yang, Xianghao Hou and Yixin Yang
Electronics 2023, 12(1), 60; https://doi.org/10.3390/electronics12010060 - 23 Dec 2022
Cited by 1 | Viewed by 1380
Abstract
Calibration of the unknown direction-dependent (DD) sensor phase and aliasing-free directions of arrival (DOA) estimation for sparse linear arrays are difficult tasks. In this work, we deploy an individual standard sensor with a known sensor phase response along the axis of the uncalibrated [...] Read more.
Calibration of the unknown direction-dependent (DD) sensor phase and aliasing-free directions of arrival (DOA) estimation for sparse linear arrays are difficult tasks. In this work, we deploy an individual standard sensor with a known sensor phase response along the axis of the uncalibrated sparse linear array, a self-calibration method is proposed, in which the unknown DD sensor phase and the aliasing-free DOAs are both estimated. The proposed method is realized with a two-step scheme. In the first step, the sensor phase is eliminated by the Kronecker product of the covariance matrices in two different frequency bins, and the frequency difference satisfies the spatial Nyquist sampling theorem. Then, the DOAs can be robustly estimated without the influences of grating lobes and unknown sensor phase parameters. In the second step, the steering matrix is estimated with the known phase parameters of the deployed standard sensor. Then, the DD sensor phase is extracted from the steering matrix using the DOAs obtained in the first step. Hence, the disadvantages of iteration-based strategies in conventional calibration algorithms (e.g., local minima convergence) can be avoided. The performance of the proposed method is evaluated using simulation data and compared with that of Cramer–Rao bounds. Full article
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23 pages, 4524 KiB  
Article
Deep Unfolded Gridless DOA Estimation Networks Based on Atomic Norm Minimization
by Hangui Zhu, Weike Feng, Cunqian Feng, Teng Ma and Bo Zou
Remote Sens. 2023, 15(1), 13; https://doi.org/10.3390/rs15010013 - 21 Dec 2022
Cited by 3 | Viewed by 2129
Abstract
Deep unfolded networks have recently been regarded as an essential way to direction of arrival (DOA) estimation due to the fast convergence speed and high interpretability. However, few consider gridless DOA estimation. This paper proposes two deep unfolded gridless DOA estimation networks to [...] Read more.
Deep unfolded networks have recently been regarded as an essential way to direction of arrival (DOA) estimation due to the fast convergence speed and high interpretability. However, few consider gridless DOA estimation. This paper proposes two deep unfolded gridless DOA estimation networks to resolve the above problem. We first consider the atomic norm-based 1D and decoupled atomic norm-based 2D gridless DOA models solved by the alternating iterative minimization of variables, respectively. Then, the corresponding deep networks are trained offline after constructing the corresponding complete training datasets. At last, the trained networks are applied to realize the 1D DOA and 2D estimation, respectively. Simulation results reveal that the proposed networks can secure higher 1D and 2D DOA estimation performances while maintaining a lower computational expenditure than typical methods. Full article
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22 pages, 855 KiB  
Article
Single-Carrier Rotation-Interleaved Space-Time Code for Frequency-Selective Fading Channels
by Benjamin K. Ng and Chan-Tong Lam
Appl. Sci. 2022, 12(24), 12803; https://doi.org/10.3390/app122412803 - 13 Dec 2022
Cited by 2 | Viewed by 1061
Abstract
A novel single-carrier-based space-time code construction scheme to exploit the advantages of a frequency-selective fading channel is investigated in this paper. The proposed construction scheme is based on multiplexing independent streams of phase-rotated space-time codes in a time-interleaved fashion. The advantage of such [...] Read more.
A novel single-carrier-based space-time code construction scheme to exploit the advantages of a frequency-selective fading channel is investigated in this paper. The proposed construction scheme is based on multiplexing independent streams of phase-rotated space-time codes in a time-interleaved fashion. The advantage of such design is that it guarantees full space-time-multipath diversity by using traditional space-time codes or MIMO signaling schemes originally designed for flat fading channels as the constituent codes. Another advantage is that this approach incurs no loss in bandwidth efficiency and it alleviates the problem of high PAPR in OFDM-based space-time codes. By employing random or algebraic rotations, the design is potentially suitable for any number of transmit antennas or multipaths. The simulation results indicate that full space-time-multipath diversity is attained using this new approach, and comparisons with some existing space-time codes designed for frequency-selective channels are made to show its performance advantage. Full article
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16 pages, 3188 KiB  
Article
A Lower Bound on the Estimation Variance of Direction-of-Arrival and Skew Angle of a Biaxial Velocity Sensor Suffering from Stochastic Loss of Perpendicularity
by Chibuzo Joseph Nnonyelu, Meng Jiang and Jan Lundgren
Sensors 2022, 22(21), 8464; https://doi.org/10.3390/s22218464 - 3 Nov 2022
Viewed by 1371
Abstract
The biaxial velocity sensor comprises two nominally perpendicular particle velocity sensors and a collocated pressure sensor. Due to real-world imperfections in manufacturing or setup errors, the two axes may suffer from perpendicularity losses. To analytically study how skewness affects its direction-finding performance, the [...] Read more.
The biaxial velocity sensor comprises two nominally perpendicular particle velocity sensors and a collocated pressure sensor. Due to real-world imperfections in manufacturing or setup errors, the two axes may suffer from perpendicularity losses. To analytically study how skewness affects its direction-finding performance, the hybrid Cramér-Rao bound (HCRB) of the directions-of-arrival for the polar angle, azimuth angle and the skew angle of a biaxial velocity sensor that suffers from stochastic loss of perpendicularity were derived in closed form. The skew angle was modeled as a zero-mean Gaussian random variable of a known variance, which was assumed to be very small, to capture the uncertainty in the orthogonality of the biaxial velocity sensor. The analysis shows that for the polar and azimuth angle, the loss of perpendicularity introduces the variation of the HCRB along the azimuth angle axis, which is independent of the skew angle, but on its variance. The dynamic range of this variation increases as the variance of the skew angle increases. For the estimation of the skew angle, the HCRB of the skew angle is bounded upwards by the variance of the skew angle and varies with the azimuth angle. The hybrid maximum likelihood- maximum a posterior (hybrid ML/MAP) estimator was used to verify the derived bounds. Full article
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15 pages, 558 KiB  
Article
A Direct Position Determination Method Based on Subspace Orthogonality in Cross-Spectra under Multipath Environments
by Kehui Zhu, Hang Jiang, Yuchong Huo, Qin Yu and Jianfeng Li
Sensors 2022, 22(19), 7245; https://doi.org/10.3390/s22197245 - 24 Sep 2022
Cited by 3 | Viewed by 1302
Abstract
Without the estimation of the intermediate parameters, the direct position determination (DPD) method can achieve higher localization accuracy than conventional two-step methods. However, multipath environments are still a key problem, and complex high-dimensional matrix operations are required in most DPD methods. In this [...] Read more.
Without the estimation of the intermediate parameters, the direct position determination (DPD) method can achieve higher localization accuracy than conventional two-step methods. However, multipath environments are still a key problem, and complex high-dimensional matrix operations are required in most DPD methods. In this paper, a time-difference-of-arrival-based (TDOA-based) DPD method is proposed based on the subspace orthogonality in the cross-spectra between the different sensors. Firstly, the cross-spectrum between the segmented received signal and reference signal is calculated and eigenvalue decomposition is performed to obtain the subspaces. Then, the cost functions are constructed by using the orthogonality of subspace. Finally, the location of the radiation source is obtained by searching the superposition of these cost functions in the target area. Compared with other DPD methods, our proposed DPD method leads to better localization accuracy with less complexity. The superiority of this method is verified by both simulated and real measured data when compared to other TDOA and DPD algorithms. Full article
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17 pages, 10105 KiB  
Article
Joint Estimation for Time Delay and Direction of Arrival in Reconfigurable Intelligent Surface with OFDM
by Jinzhi Du, Weijia Cui, Bin Ba, Chunxiao Jian and Liye Zhang
Sensors 2022, 22(18), 7083; https://doi.org/10.3390/s22187083 - 19 Sep 2022
Cited by 1 | Viewed by 1770
Abstract
Recently, the joint estimation for time delay (TD) and direction of arrival (DOA) has suffered from the high complexity of processing multi-dimensional signal models and the ineffectiveness of correlated/coherent signals. In order to improve this situation, a joint estimation method using orthogonal frequency [...] Read more.
Recently, the joint estimation for time delay (TD) and direction of arrival (DOA) has suffered from the high complexity of processing multi-dimensional signal models and the ineffectiveness of correlated/coherent signals. In order to improve this situation, a joint estimation method using orthogonal frequency division multiplexing (OFDM) and a uniform planar array composed of reconfigurable intelligent surface (RIS) is proposed. First, the time-domain coding function of the RIS is combined with the multi-carrier characteristic of the OFDM signal to construct the coded channel frequency response in tensor form. Then, the coded channel frequency response covariance matrix is decomposed by CANDECOMP/PARAFAC (CPD) to separate the signal subspaces of TD and DOA. Finally, we perform a one-dimensional (1D) spectral search for TD values and a two-dimensional (2D) spectral search for DOA values. Compared to previous efforts, this algorithm not only enhances the adaptability of coherent signals, but also greatly decreases the complexity. Simulation results indicate the robustness and effectiveness for the proposed algorithm in independent, coherent, and mixed multipath environments and low signal-to-noise ratio (SNR) conditions. Full article
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12 pages, 1586 KiB  
Article
Flexible Null Broadening Robust Beamforming Based on JADE
by Yulong Liu, Yingzeng Yin, Ruilong Li and Ru Fang
Appl. Sci. 2022, 12(18), 9329; https://doi.org/10.3390/app12189329 - 17 Sep 2022
Cited by 2 | Viewed by 1185
Abstract
In order to flexibly and completely suppress dynamic interference, a flexible and robust beamforming based on JADE is proposed in this paper. In addition, it is insensitive to the gain–phase errors of the array. Firstly, the actual steering vector with gain–phase errors is [...] Read more.
In order to flexibly and completely suppress dynamic interference, a flexible and robust beamforming based on JADE is proposed in this paper. In addition, it is insensitive to the gain–phase errors of the array. Firstly, the actual steering vector with gain–phase errors is separated from the received snapshot data by the joint approximate diagonalization of eigenmatrix (JADE) algorithm. Secondly, the direction of arrival (DOA) of interference can be estimated from the separated actual steering vector by the correlation coefficient method. Thus, the actual interference steering vector with gain–phase errors can be selected by the correlation coefficient with the nominal steering vector constructed by the estimated DOA. Then, the interference covariance matrix can be reconstructed by the actual interference steering vector, and the interference power estimated by the Capon power spectral. Finally, according to the prior information of the interference, only the dynamic interference covariance matrix is tapered by the novel covariance matrix trap (CMT), which can flexibly broaden and deepen the null. Simulation results show that the depth of the proposed beamformer is more than 10 dB deeper than that of the traditional algorithm in the non-stationary interference. In addition, it can save at least 2 degrees of freedom compared to the traditional method. Full article
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11 pages, 1658 KiB  
Article
Deep Neural Network for 3D Shape Classification Based on Mesh Feature
by Mengran Gao, Ningjun Ruan, Junpeng Shi and Wanli Zhou
Sensors 2022, 22(18), 7040; https://doi.org/10.3390/s22187040 - 17 Sep 2022
Cited by 5 | Viewed by 7566
Abstract
Virtual reality, driverless cars, and robotics all make extensive use of 3D shape classification. One of the most popular ways to represent 3D data is with polygonal meshes. In particular, triangular mesh is frequently employed. A triangular mesh has more features than 3D [...] Read more.
Virtual reality, driverless cars, and robotics all make extensive use of 3D shape classification. One of the most popular ways to represent 3D data is with polygonal meshes. In particular, triangular mesh is frequently employed. A triangular mesh has more features than 3D data formats such as voxels, multi-views, and point clouds. The current challenge is to fully utilize and extract useful information from mesh data. In this paper, a 3D shape classification network based on triangular mesh and graph convolutional neural networks was suggested. The triangular face of this model was viewed as a unit. By obtaining an adjacency matrix from mesh data, graph convolutional neural networks can be utilized to process mesh data. The studies were performed on the ModelNet40 dataset with an accuracy of 91.0%, demonstrating that the classification network in this research may produce effective results. Full article
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18 pages, 3673 KiB  
Article
Null Broadening Robust Adaptive Beamforming Algorithm Based on Power Estimation
by Zhenhua Yu, Weijia Cui, Yuxi Du, Bin Ba and Mengjiao Quan
Sensors 2022, 22(18), 6984; https://doi.org/10.3390/s22186984 - 15 Sep 2022
Cited by 2 | Viewed by 1436
Abstract
In order to solve the problem of severely decreased performance under the situation of rapid moving sources and unstable array platforms, a null broadening robust adaptive beamforming algorithm based on power estimation is proposed in this paper. First of all, we estimate the [...] Read more.
In order to solve the problem of severely decreased performance under the situation of rapid moving sources and unstable array platforms, a null broadening robust adaptive beamforming algorithm based on power estimation is proposed in this paper. First of all, we estimate the interference signal power according to the characteristic subspace theory. Then, the correspondence between the signal power and steering vector (SV) is obtained based on the orthogonal property, and the interference covariance matrix (ICM) is reconstructed. Finally, with the aim of setting virtual interference sources, null broadening can be carried out. The proposed algorithm results in a deeper null, lower side lobes and higher tolerance of the desired signal steering vector mismatch under the condition of low complexity. The simulation results show that the algorithm also has stronger robustness. Full article
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21 pages, 5608 KiB  
Article
Distributed Satellite Relay Cooperative Communication with Optimized Signal Space Dimension
by Yong Wang, Xiyuan Wang, Qiao Liu and Hui Li
Remote Sens. 2022, 14(18), 4474; https://doi.org/10.3390/rs14184474 - 8 Sep 2022
Cited by 1 | Viewed by 1571
Abstract
With the increasingly obvious trend of satellite communication and network integration, especially the emergence of inter satellite links, the interconnection between space nodes has become the development trend and inevitable requirement of future space communication. However, problems, such as long communication distance, large [...] Read more.
With the increasingly obvious trend of satellite communication and network integration, especially the emergence of inter satellite links, the interconnection between space nodes has become the development trend and inevitable requirement of future space communication. However, problems, such as long communication distance, large transmission delay and loss, limited network resources and frequent switching of transmission links, limit the ability of spatial information transmission. Firstly, based on the idea of ring planning and design, this paper uses the joint design of beamforming between nodes to design the physical layer network coding in the relay to realize the reliable transmission of information. Secondly, according to the diversity of relay signal space resources and network node information exchange, a joint design method of relay compression matrix and node precoding vector is studied, which breaks through the existing configuration constraints. In this scheme, the computational complexity is reduced by compressing and precoding the matrix to ensure reliable decoding while obtaining spatial alignment gain and degrees of freedom. Simulated and real data results demonstrate the superiority and effectiveness of the proposed method. Full article
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23 pages, 4302 KiB  
Article
A Dynamic Self-Tuning Maximum Correntropy Kalman Filter for Wireless Sensors Networks Positioning Systems
by Tianrui Liao, Kaoru Hirota, Xiangdong Wu, Shuai Shao and Yaping Dai
Remote Sens. 2022, 14(17), 4345; https://doi.org/10.3390/rs14174345 - 1 Sep 2022
Cited by 4 | Viewed by 1637
Abstract
To improve the accuracy of the maximum correntropy Kalman filter (MCKF) in wireless sensors networks (WSNs) positioning, a dynamic self-tuning maximum correntropy Kalman filter (DSTMCKF) is proposed, where innovation and the sensors information of the WSNs are used to adjust the noise covariance [...] Read more.
To improve the accuracy of the maximum correntropy Kalman filter (MCKF) in wireless sensors networks (WSNs) positioning, a dynamic self-tuning maximum correntropy Kalman filter (DSTMCKF) is proposed, where innovation and the sensors information of the WSNs are used to adjust the noise covariance matrices, and the maximum correntropy criterion is the criterion for the filter’s optimality. By dynamically adjusting the noise covariance matrices, the DSTMCKF ensures that the correntropy distribution is accurate in the presence of non-Gaussian noise (NGN), thus improving its ability to handle the NGN. In simulation and real environment positioning experiments, the DSTMCKF is used to compare with the MCKF, variable kernel width–maximum correntropy Kalman filter (VKW-MCKF) and robust minimum error entropy Kalman filter (R-MEEKF). Among the four filters, the DSTMCKF has the highest accuracy, and the error of the DSTMCKF is reduced by 34.5, 42.9 and 40.0%, respectively, compared with the MCKF, VKW-MCKF and R-MEEKF in the real-world environment positioning experiment. The application of the DSTMCKF in WSNs positioning systems improves the stability of the control systems because of the rising positioning accuracy, which makes WSNs positioning systems more widely used in scenarios requiring high stability, such as automatic parking. Full article
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14 pages, 6047 KiB  
Communication
Coherent Targets Parameter Estimation for EVS-MIMO Radar
by Xueke Ding, Ying Hu, Changming Liu and Qun Wan
Remote Sens. 2022, 14(17), 4331; https://doi.org/10.3390/rs14174331 - 1 Sep 2022
Cited by 5 | Viewed by 1257
Abstract
As an emerging technique for detection, electromagnetic vector sensor multiple-input multiple-output (EVS-MIMO) radar has attracted extensive interest recently. This paper focuses on the coherent targets issue in EVS-MIMO radar, and a spatial smoothing estimator is developed to estimate the multiple parameters. It first [...] Read more.
As an emerging technique for detection, electromagnetic vector sensor multiple-input multiple-output (EVS-MIMO) radar has attracted extensive interest recently. This paper focuses on the coherent targets issue in EVS-MIMO radar, and a spatial smoothing estimator is developed to estimate the multiple parameters. It first recovers the rank of the array data via forward spatial smoothing. Then, it estimates the elevation angles via the rotational invariance technique. Combined with the vector cross-product method, the azimuth angles are obtained. Thereafter, with the previously achieved direction angles, the polarized parameters are acquired by using the least squares technique. Unlike the existing polarization smoothing techniques, the proposed estimator is able to estimate the two-dimensional direction parameter. Furthermore, it can provide a polarized parameter of the target. In addition, the proposed estimator is computationally efficient, since it offers closed-form and automatically paired solutions to all the parameters. Numerical experiments are carried out to show its superiority and effectiveness. Full article
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18 pages, 8003 KiB  
Article
Joint Satellite-Transmitter and Ground-Receiver Digital Pre-Distortion for Active Phased Arrays in LEO Satellite Communications
by Qingyue Chen, Zhugang Wang, Gert Frølund Pedersen and Ming Shen
Remote Sens. 2022, 14(17), 4319; https://doi.org/10.3390/rs14174319 - 1 Sep 2022
Cited by 8 | Viewed by 2750
Abstract
A novel joint satellite-transmitter and ground-receiver (JSG) digital pre-distortion (DPD) (JSG-DPD) technique is proposed to improve the linearity and power efficiency of the space-borne active phased arrays (APAs) in low Earth orbit (LEO) satellite communications. Different from the conventional DPD technique that requires [...] Read more.
A novel joint satellite-transmitter and ground-receiver (JSG) digital pre-distortion (DPD) (JSG-DPD) technique is proposed to improve the linearity and power efficiency of the space-borne active phased arrays (APAs) in low Earth orbit (LEO) satellite communications. Different from the conventional DPD technique that requires a complex RF feedback loop, the DPD coefficients based on a generalized memory polynomial (GMP) model are extracted at the ground-receiver and then transmitted to the digital baseband front-end of the LEO satellite-transmitter via a satellite–ground bi-directional transmission link. The issue of the additive white Gaussian noise (AWGN) of the satellite–ground channel affecting the extraction of DPD coefficients is tackled using a superimposing training sequences (STS) method. The proposed technique has been experimentally verified using a 28 GHz phased array. The performance improvements in terms of error vector amplitude (EVM) and adjacent channel power ratio (ACPR) are 7.5% and 3.6 dB, respectively. Requiring limited space-borne resources, this technique offers a promising solution to achieve APA DPD for LEO satellite communications. Full article
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10 pages, 1869 KiB  
Communication
Real Valued MUSIC Method for Height Measurement of Meter Wave Polarimetric MIMO Radar Based on Matrix Reconstruction
by Guimei Zheng, Chen Chen and Yuwei Song
Remote Sens. 2022, 14(16), 4121; https://doi.org/10.3390/rs14164121 - 22 Aug 2022
Cited by 2 | Viewed by 1462
Abstract
Combining the advantages of diversity provided by polarization MIMO radar and good decoherence ability of matrix reconstruction technology, a method for height measurements based on matrix reconstruction after real valued processing is developed. To solve height measurement problem in meter wave polarization MIMO [...] Read more.
Combining the advantages of diversity provided by polarization MIMO radar and good decoherence ability of matrix reconstruction technology, a method for height measurements based on matrix reconstruction after real valued processing is developed. To solve height measurement problem in meter wave polarization MIMO radar, we first derive the corresponding flat ground signal model; then, the received data matrix is reconstructed to eliminate the influence of multipath coherent signal on height measurements. Then, the reconstructed data matrix is transformed into a real valued matrix using a unitary matrix. In order to reduce the influence of noise on the signal subspace and reduce the data dimension, singular value decomposition technology is applied to receive the signal data. Finally, the elevation and height of the target are estimated according to the principle that the signal subspace is orthogonal to the noise subspace. The proposed method does not require prior knowledge, such as the reflection coefficient, wave path difference and polarization information. Simulation experiments show that the proposed algorithm has better estimation performance and less computational complexity than conventional algorithms. Full article
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23 pages, 2265 KiB  
Article
Identifiability Analysis for Configuration Calibration in Distributed Sensor Networks
by Xiaoyu Liu, Tong Wang and Jinming Chen
Remote Sens. 2022, 14(16), 3920; https://doi.org/10.3390/rs14163920 - 12 Aug 2022
Cited by 3 | Viewed by 1209
Abstract
In this work, the parameter identifiability of sensor position perturbations in a distributed network is analyzed through establishing the link between rank of the Jacobian matrix and parameter identifiability under Gaussian noise. Here, the calibration is classified as either external or internal, dependent [...] Read more.
In this work, the parameter identifiability of sensor position perturbations in a distributed network is analyzed through establishing the link between rank of the Jacobian matrix and parameter identifiability under Gaussian noise. Here, the calibration is classified as either external or internal, dependent on whether auxiliary sources are exploited. It states that, in the case of internal calibration, sensor position perturbations can be precisely calibrated when the position of a sensor and orientation to a second sensor along with the coordinate of a third sensor along some axis, are known. In the case of external calibration where auxiliary sources are introduced to support the process, the identifiability condition for configuration calibration is to have at least three noncollinear auxiliary sources with the distributed sensor network avoiding the collinear and coplanar geometries. As the assumption of small perturbations is considered, the parameter identifiability is capable of being measured by virtue of the Bayesian Cramer–Rao lower bound (BCRLB), after asymptotical tightness of the BCRLB is verified. Simulations corroborate well with the theoretical development. Full article
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20 pages, 1328 KiB  
Article
Enhanced Multiscale Principal Component Analysis for Improved Sensor Fault Detection and Isolation
by Byanne Malluhi, Hazem Nounou and Mohamed Nounou
Sensors 2022, 22(15), 5564; https://doi.org/10.3390/s22155564 - 26 Jul 2022
Cited by 4 | Viewed by 1978
Abstract
Multiscale PCA (MSPCA) is a well-established fault-detection and isolation (FDI) technique. It utilizes wavelet analysis and PCA to extract important features from process data. This study demonstrates limitations in the conventional MSPCA fault detection algorithm, thereby proposing an enhanced MSPCA (EMSPCA) FDI algorithm [...] Read more.
Multiscale PCA (MSPCA) is a well-established fault-detection and isolation (FDI) technique. It utilizes wavelet analysis and PCA to extract important features from process data. This study demonstrates limitations in the conventional MSPCA fault detection algorithm, thereby proposing an enhanced MSPCA (EMSPCA) FDI algorithm that uses a new wavelet thresholding criterion. As such, it improves the projection of faults in the residual space and the threshold estimation of the fault detection statistic. When tested with a synthetic model, EMSPCA resulted in a 30% improvement in detection rate with equal false alarm rates. The EMSPCA algorithm also relies on the novel application of reconstruction-based fault isolation at multiple scales. The proposed algorithm reduces fault smearing and consequently improves fault isolation performance. The paper will further investigate the use of soft vs. hard wavelet thresholding, decimated vs. undecimated wavelet transforms, the choice of wavelet decomposition depth, and their implications on FDI performance.The FDI performance of the developed EMSPCA method was illustrated for sensor faults. This undertaking considered synthetic data, the simulated data of a continuously stirred reactor (CSTR), and experimental data from a packed-bed pilot plant. The results of these examples show the advantages of EMSPCA over existing techniques. Full article
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19 pages, 797 KiB  
Article
Low-Elevation Target DOA Estimation Based on Multi-Scattering Center Equivalent Model
by Jianjun Ma, Hongwei Liu and Hui Ma
Remote Sens. 2022, 14(15), 3533; https://doi.org/10.3390/rs14153533 - 23 Jul 2022
Cited by 1 | Viewed by 1429
Abstract
In very-high-frequency (VHF) radar, the direction-of-arrival (DOA) estimation performance of low-angle targets tracking is strongly affected by the multipath phenomenon. Especially in the complex terrain conditions, the multipath echo comes from a region where the different scattering media make the multipath echo show [...] Read more.
In very-high-frequency (VHF) radar, the direction-of-arrival (DOA) estimation performance of low-angle targets tracking is strongly affected by the multipath phenomenon. Especially in the complex terrain conditions, the multipath echo comes from a region where the different scattering media make the multipath echo show the characteristics of multi-channel and uneven energy distribution. In this case, the received signal mismatches with the signal model, which leads to performance degradation and even failure of the traditional DOA algorithm. To deal with this problem, the authors propose a new signal model based on multiple scattering center. A multipath signal equivalent model is deduced and analyzed using multipath vector synthesis. Subsequently, the fitness function is established based on the equivalent model, and the target elevation angle is estimated by particle swarm optimization (PSO) algorithm. Simulation results and real data analysis show that the proposed model and algorithm can effectively improve the DOA estimation accuracy of low elevation target under complex terrain and less snapshot condition. Full article
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14 pages, 2286 KiB  
Communication
DOA Estimation in B5G/6G: Trends and Challenges
by Ningjun Ruan, Han Wang, Fangqing Wen and Junpeng Shi
Sensors 2022, 22(14), 5125; https://doi.org/10.3390/s22145125 - 8 Jul 2022
Cited by 15 | Viewed by 3572
Abstract
Direction-of-arrival (DOA) estimation is the preliminary stage of communication, localization, and sensing. Hence, it is a canonical task for next-generation wireless communications, namely beyond 5G (B5G) or 6G communication networks. Both massive multiple-input multiple-output (MIMO) and millimeter wave (mmW) bands are emerging technologies [...] Read more.
Direction-of-arrival (DOA) estimation is the preliminary stage of communication, localization, and sensing. Hence, it is a canonical task for next-generation wireless communications, namely beyond 5G (B5G) or 6G communication networks. Both massive multiple-input multiple-output (MIMO) and millimeter wave (mmW) bands are emerging technologies that can be implemented to increase the spectral efficiency of an area, and a number of expectations have been placed on them for future-generation wireless communications. Meanwhile, they also create new challenges for DOA estimation, for instance, through extremely large-scale array data, the coexistence of far-field and near-field sources, mutual coupling effects, and complicated spatial-temporal signal sampling. This article discusses various open issues related to DOA estimation for B5G/6G communication networks. Moreover, some insights on current advances, including arrays, models, sampling, and algorithms, are provided. Finally, directions for future work on the development of DOA estimation are addressed. Full article
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17 pages, 1569 KiB  
Article
Target Height Measurement under Complex Multipath Interferences without Exact Knowledge on the Propagation Environment
by Yuan Liu and Hongwei Liu
Remote Sens. 2022, 14(13), 3099; https://doi.org/10.3390/rs14133099 - 28 Jun 2022
Cited by 5 | Viewed by 2697
Abstract
This paper investigates the direction-of-arrival (DOA) estimation-based target localization problem using an array radar under complex multipath propagation scenarios. Prevalent methods may suffer from performance degradation due to the deterministic signal model mismatch, especially when the exact knowledge of a propagation environment is [...] Read more.
This paper investigates the direction-of-arrival (DOA) estimation-based target localization problem using an array radar under complex multipath propagation scenarios. Prevalent methods may suffer from performance degradation due to the deterministic signal model mismatch, especially when the exact knowledge of a propagation environment is unavailable. To cope with this problem, we first establish an improved signal model of multipath propagation for low-angle target localization scenarios, where the dynamic nature of convoluted interferences induced by complex terrain reflections is taken into account. Subsequently, an iterative implementation-based target localization algorithm with the improved propagation model is proposed to eliminate the detrimental effect of coherent interferences on target localization performance. Compared to existing works, the proposed algorithm can maintain satisfactory estimation performance in terms of target location parameters, even in severe multipath interference conditions, where the decorrelation preprocessing and accurate knowledge about the multipath propagation environment are not required. Both simulation and experimental results demonstrate the effectiveness of the proposed propagation model and localization algorithm. Full article
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20 pages, 509 KiB  
Article
A Fast PARAFAC Algorithm for Parameter Estimation in Monostatic FDA-MIMO Radar
by Wenshuai Wang, Xiang Lan, Jinmei Shi and Xianpeng Wang
Remote Sens. 2022, 14(13), 3093; https://doi.org/10.3390/rs14133093 - 27 Jun 2022
Cited by 3 | Viewed by 1524
Abstract
This paper studies the joint range and angle estimation of monostatic frequency diverse array multiple-input multiple-output (FDA-MIMO) radar and proposes a joint estimation algorithm. First, the transmit direction matrix is converted into real values by unitary transformation, and the Vandermonde-like matrix structure is [...] Read more.
This paper studies the joint range and angle estimation of monostatic frequency diverse array multiple-input multiple-output (FDA-MIMO) radar and proposes a joint estimation algorithm. First, the transmit direction matrix is converted into real values by unitary transformation, and the Vandermonde-like matrix structure is used to construct an augmented output that doubles the aperture of the receive array. Then the augmented output is combined into a third-order tensor. Next, the factor matrices are initially estimated. Finally, the direction matrices are estimated utilizing parallel factor (PARAFAC) decomposition, and the range and angle are calculated by employing least square fitting. As contrasted with the classic PARAFAC method, the proposed method can estimate more targets and provide better estimation performance, and requires less computational complexity. The availability and excellence of the proposed method are reflected by numerical simulations and complexity analysis. Full article
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17 pages, 3230 KiB  
Article
Low-Complexity 2D DOA Estimation and Self-Calibration for Uniform Rectangle Array with Gain-Phase Error
by Yiduo Guo, Xiaowei Hu, Weike Feng and Jian Gong
Remote Sens. 2022, 14(13), 3064; https://doi.org/10.3390/rs14133064 - 26 Jun 2022
Cited by 6 | Viewed by 1942
Abstract
Most subspace-based algorithms need exact array manifold for direction of arrival (DOA) estimation, while, in practical applications, the gain-phases of different array elements are usually inconsistent, degrading their estimation performance. In this paper, a novel low-complexity 2D DOA and gain-phase error estimation algorithm [...] Read more.
Most subspace-based algorithms need exact array manifold for direction of arrival (DOA) estimation, while, in practical applications, the gain-phases of different array elements are usually inconsistent, degrading their estimation performance. In this paper, a novel low-complexity 2D DOA and gain-phase error estimation algorithm is proposed by adding auxiliary array elements in a uniform rectangular array (URA). Firstly, the URA is modeled as the Kronecker product of two uniform linear arrays (ULAs) to decouple the 2D DOA estimation. Then, several well-calibrated auxiliary array elements are added in the two ULAs, based on which the rotation invariant factor of the URA destroyed by the gain-phase error is reconstructed by solving constrained optimization problems. Lastly, ESPRIT is used to estimate the 2-D DOA and the gain-phase error coefficients. The closed-form expressions of the estimation CRBs are also derived, providing insight into the impact of gain-phase error on DOA estimation. Simulation results are used to validate the effectiveness of the proposed algorithm and the correctness of the theoretical analysis. Full article
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17 pages, 5651 KiB  
Article
Spatial Spectral Enhancement of Broadband Signals in a Towed Array Using Deconvolved Subband Peak Energy Detection
by Anbang Zhao, Keren Wang, Juan Hui, Caigao Zeng and Kaiyu Tang
Remote Sens. 2022, 14(13), 3008; https://doi.org/10.3390/rs14133008 - 23 Jun 2022
Cited by 2 | Viewed by 1860
Abstract
Conventional energy detection is a robust method that is usually applied to underwater broadband acoustic signal processing for towed arrays. Due to its low resolution, the weak target detection performance of conventional energy detection is severely degraded in shallow sea environments with strong [...] Read more.
Conventional energy detection is a robust method that is usually applied to underwater broadband acoustic signal processing for towed arrays. Due to its low resolution, the weak target detection performance of conventional energy detection is severely degraded in shallow sea environments with strong acoustical reverberation. Subband peak energy detection is an effective method to improve the display resolution of conventional energy detection. However, subband peak energy detection produces false alarms due to the presence of high sidelobe levels. In order to improve the underwater target detection performance, a deconvolved subband peak energy detection method for towed arrays is proposed in this paper. Compared with conventional beamforming, minimum-variance distortionless response with forward–backward averaging and diagonal loading algorithm and subband peak energy detection, the proposed method could robustly provide higher-resolution results and suppress the fake peaks induced by subband peak energy detection. The performance of the proposed method was evaluated with simulation results, and the sea experimental data processing results show that the proposed method is effective in engineering applications. Full article
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26 pages, 8266 KiB  
Article
Lightweight Self-Detection and Self-Calibration Strategy for MEMS Gas Sensor Arrays
by Bing Liu, Yanzhen Zhou, Hongshuo Fu, Ping Fu and Lei Feng
Sensors 2022, 22(12), 4315; https://doi.org/10.3390/s22124315 - 7 Jun 2022
Cited by 7 | Viewed by 2219
Abstract
With the development of Internet of Things (IoT) and edge computing technology, gas sensor arrays based on Micro-Electro-Mechanical System (MEMS) fabrication technique have broad application prospects in intelligent integrated systems, portable devices, and other fields. In such complex scenarios, the normal operation of [...] Read more.
With the development of Internet of Things (IoT) and edge computing technology, gas sensor arrays based on Micro-Electro-Mechanical System (MEMS) fabrication technique have broad application prospects in intelligent integrated systems, portable devices, and other fields. In such complex scenarios, the normal operation of a gas sensing system depends heavily on the accuracy of the sensor output. Therefore, a lightweight Self-Detection and Self-Calibration strategy for MEMS gas sensor arrays is proposed in this paper to monitor the working status of sensor arrays and correct the abnormal data in real time. Evaluations on real-world datasets indicate that the strategy has high performance of fault detection, isolation, and data recovery. Furthermore, our method has low computation complexity and low storage resource occupation. The board-level verification on CC1350 shows that the average calculation time and running power consumption of the algorithm are 0.28 ms and 9.884 mW. The proposed strategy can be deployed on most resource-limited IoT devices to improve the reliability of gas sensing systems. Full article
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24 pages, 5125 KiB  
Article
Robust Space–Time Joint Sparse Processing Method with Airborne Active Array for Severely Inhomogeneous Clutter Suppression
by Qiang Wang, Bin Xue, Xiaowei Hu, Guangen Wu and Weihu Zhao
Remote Sens. 2022, 14(11), 2647; https://doi.org/10.3390/rs14112647 - 1 Jun 2022
Cited by 1 | Viewed by 1553
Abstract
Due to clutter inhomogeneity, the clutter suppression ability of space–time adaptive processing (STAP) is usually constrained by the insufficient number of independent and identically distributed (IID) clutter training samples and, as a result, is sacrificed to achieve the demanded sample reduction. Moreover, since [...] Read more.
Due to clutter inhomogeneity, the clutter suppression ability of space–time adaptive processing (STAP) is usually constrained by the insufficient number of independent and identically distributed (IID) clutter training samples and, as a result, is sacrificed to achieve the demanded sample reduction. Moreover, since clutter heterogeneity is exacerbated in the real environment, the IID training sample size can be heavily reduced, leading to the deterioration in clutter suppression. To solve this problem, a novel robust space–time joint sparse processing method with airborne active array is proposed. This method has several outstanding advantages: (1) only the single snapshot cell under test (CUT) data is used for the superior clutter suppression performance; and (2) the proposed method completely removes the dependence of the system processing ability on IID training samples. In this paper, the signal model of uniform transmitting subarray diversity is first established to obtain the single snapshot echo observed CUT data. Then, with the matched reconstruction, the single snapshot data are equivalently converted into multi-frame echo data. Finally, a fast multi-frame echo data joint sparse Bayesian algorithm is used to achieve heterogeneous clutter suppression. Numerous experiments were performed to verify the advantages of the proposed method. Full article
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18 pages, 3500 KiB  
Article
Acoustic Estimation of the Direction of Arrival of an Unmanned Aerial Vehicle Based on Frequency Tracking in the Time-Frequency Plane
by Nathan Itare, Jean-Hugh Thomas, Kosai Raoof and Torea Blanchard
Sensors 2022, 22(11), 4021; https://doi.org/10.3390/s22114021 - 26 May 2022
Cited by 4 | Viewed by 1889
Abstract
The development of unmanned aerial vehicles (UAVs) opens up a lot of opportunities but also brings some threats. Dealing with these threats is not easy and requires some good techniques. Knowing the location of the threat is essential to deal with an UAV [...] Read more.
The development of unmanned aerial vehicles (UAVs) opens up a lot of opportunities but also brings some threats. Dealing with these threats is not easy and requires some good techniques. Knowing the location of the threat is essential to deal with an UAV that is displaying disturbing behavior. Many methods exist but can be very limited due to the size of UAVs or due to technological improvements over the years. However, the noise produced by the UAVs is still predominant, so it gives a good opening for the development of acoustic methods. The method presented here takes advantage of a microphone array with a processing based on time domain Delay and Sum Beamforming. In order to obtain a better signal to noise ratio, the UAV’s acoustic signature is taken into account in the processing by using a time-frequency representation of the beamformer’s output. Then, only the content related to this signature is considered to calculate the energy in one direction. This method enables to have a good robustness to noise and to localize an UAV with a poor spectral content or to separate two UAVs with different spectral contents. Simulation results and those of a real flight experiment are reported. Full article
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