| 1. |
- Etzlinger, B., et al.
(author)
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Cooperative simultaneous localization and synchronization: Toward a low-cost hardware implementation
- 2014
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In: Proceedings of the IEEE Sensor Array and Multichannel Signal Processing Workshop. - 2151-870X. - 9781479914814 ; , s. 33-36
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Conference paper (peer-reviewed)abstract
- Cooperative sensor self-localization (CSL) in wireless networks usually requires the nodes to be equipped with specific ranging hardware including ultra-wideband or ultrasonic distance sensors. Such designs are not suitable for application in low-cost, low-power sensor networks. Here, we demonstrate how low-cost, low-power, asynchronous sensor nodes can be used to perform CSL (and, simultaneously, distributed synchronization) by means of time-stamped communication without additional ranging hardware. Our method combines a belief propagation message passing algorithm for cooperative simultaneous localization and synchronization (CoSLAS) with a MAC-layer time stamping scheme.We validate the models underlying the CoSLAS algorithm by means of measurements, and we demonstrate that the localization accuracy achieved by our hardware implementation is far better than that corresponding to the time resolution and measurement errors of the hardware.
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| 2. |
- Panahi, Ashkan, 1986, et al.
(author)
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Basis pursuit over continuum applied to range-Doppler estimation problem
- 2014
-
In: Proceedings of the IEEE Sensor Array and Multichannel Signal Processing Workshop. - 2151-870X. - 9781479914814 ; , s. 381-384
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Conference paper (peer-reviewed)abstract
- Sparse estimation and compressive sensing techniques have been recently considered for radar estimation problems. It is frequently observed that these methods are robust to model uncertainties and substantially improve performance in scenarios with a low signal-to-noise. However, since current sparsity-based techniques are computationally costly and require a suitable discretization (grid), which strongly restricts resolution, they practically receive less attention. In this work, we present an application of a new sparsity-based technique to the specific problem of range-Doppler estimation. The method, generalizing basis pursuit, is less computationally complex and its performance is independent of the grid selection. We demonstrate that the proposed technique can improve estimation performance in difficult cases, as compared to the SAGE technique.
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| 3. |
- Ström, Marie, 1984, et al.
(author)
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Wideband waveform design for clutter suppression
- 2014
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In: Proceedings of the IEEE Sensor Array and Multichannel Signal Processing Workshop. - 2151-870X. - 9781479914814 ; :Art. no. 6882399, s. 297-300
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Conference paper (peer-reviewed)abstract
- Modern signal generators offer the capability to synthesize arbitrary wideband waveforms for radar and sonar applications. This makes it possible to optimize signals for specific purposes or scenarios. Herein, we discuss how to design a wideband waveform for clutter suppression. We formulate an optimization in terms of mainlobe and sidelobe properties of the ambiguity function, then we provide an approximate solution based on convex relaxation. Numerical evaluation shows the advantage of selecting a smart signal compared to a conventional waveform design. The advantages are shown as a lower probability of false alarm and a higher probability of correct target detection.
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| 4. |
- Andersson, Carl, 1992, et al.
(author)
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A Method for Simultaneous Creation of an Acoustic Trap and a Quiet Zone
- 2018
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In: Proceedings of the IEEE Sensor Array and Multichannel Signal Processing Workshop. - 2151-870X. ; 2018-July, s. 622-626
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Conference paper (peer-reviewed)abstract
- An acoustical levitation trap can be created by max- imizing the Laplacian of the Gor’kov potential and minimizing the pressure at a given location. Marzo et al. have successfully used Broyden-Fletcher-Goldfarb-Shanno minimization to find the phases to be imposed on the elements of an ultrasonic transducer array to create the required pressure field. We extend this method to create a field with one acoustical trap and a quiet zone at a different location. This can be used to, for example, create an independent second trap at the location of the quiet zone. We show through numerical simulations that it is possible to create such sound fields using ultrasonic arrays, and we demonstrate the advantages of the proposed approach over the direct design of a sound field with more than one trap. Our method can create a quiet zone extending almost two wavelengths without affecting the levitation trap.
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| 5. |
- Björklund, Svante, et al.
(author)
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A three-dimensional displaced phase center antenna condition for clutter cancellation
- 2014
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In: Proceedings of the IEEE Sensor Array and Multichannel Signal Processing Workshop. - : IEEE. - 9781479914814 ; , s. 305-308
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Conference paper (peer-reviewed)abstract
- In moving radar, e.g. airborne radar, the clutter from land and sea needs to be suppressed in order to detect the target. One approach to total cancellation of the clutter is Displaced Phase Center Antenna (DPCA). DPCA assumes that the antenna elements are positioned on a line parallel to the velocity vector of the radar platform so that the elements can take each others positions at different points of times. This paper theoretically investigates if it is possible with other antenna element positions, e.g. in three dimensions, for a total cancellation of the clutter. We arrive at a condition which conforms to the principle that the elements should take each others positions at different times but allows other antennas than the single line parallel to the velocity vector. Our condition could be used as constraints in an optimization problem where the target signal performance is optimized. The multipulse DPCA condition is one solution to our condition.We also give two examples of non-linear antennas fulfilling our condition.
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| 6. |
- Ciuonzo, Domenico, et al.
(author)
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Massive MIMO meets decision fusion : Decode-and-fuse vs. decode-then-fuse
- 2014
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In: 2014 IEEE 8TH Sensor Array and Multichannel Signal Processing Workshop (SAM). - 9781479914814 ; , s. 265-268
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Conference paper (peer-reviewed)abstract
- We study channel-aware decision fusion over a multiple-input multiple-output (MIMO) channel in the large-array regime at the decision-fusion center (DFC). Inhomogeneous large-scale fading between the sensors and the DFC is consider in addition to the small-scale fading, and pilot-based channel estimation is performed at the DFC. Linear processing techniques are analyzed in order to design low-complexity alternatives to the optimum log-likelihood ratio test (LLRT). Performance evaluation based on Monte Carlo simulations are presented.
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| 7. |
- Klintberg, Jacob, 1994, et al.
(author)
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Mitigation of Ground Clutter in Airborne Bistatic Radar Systems
- 2020
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In: Proceedings of the IEEE Sensor Array and Multichannel Signal Processing Workshop. - 2151-870X. ; 2020-June
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Conference paper (peer-reviewed)abstract
- Space-Time Adaptive Processing is a commonly used technique to mitigate ground clutter reflections from an airborne radar system. It estimates a covariance matrix based on spatial and temporal information, and the estimate is thereafter used to suppress the ground clutter. In a side-looking monostatic radar system, the estimate is rather straight forward based on radar observations. However, in this paper, we consider bistatic systems where the power of adaptivity is limited due to nonstationarity of the ground clutter reflections over the range dimension. To overcome this, scenario dependent transformations are commonly used when forming the sample covariance matrix. In this contribution we instead investigate a detector where the clutter covariance matrix is determined from the geometry of the bistatic scenario. Using a Monte-Carlo simulation, we investigate how sensitive the detector is to errors in the assumed geometry, and compare this with state-of-the-art adaptive methods. The results indicates that a good clutter rejection is obtained for errors of order 103 m for assumed transmitter position and 100km/h for assumed transmitter velocity.
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| 8. |
- Kylin, Carl, 1996, et al.
(author)
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Over-The-Air Identification of Coupled Nonlinear Distortion in a MIMO Radar
- 2022
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In: Proceedings of the IEEE Sensor Array and Multichannel Signal Processing Workshop. - 2151-870X. ; 2022-June, s. 121-125
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Conference paper (peer-reviewed)abstract
- Compensation for nonlinear distortion caused by power amplifiers being driven into compression is a field that has been extensively explored by a number of authors. More complex models describing the coupled nonlinear distortion that can occur in an active antenna array also exist. To identify these models most authors assume that the output of each power amplifier can be measured directly. For a system with many antennas over-the-air identification might be favorable. The problem of identifying a system describing the joint effects of coupled nonlinear distortion over-the-air has been solved by other authors assuming model or setup simplifications. To tackle the problem with a more accurate model, an algorithm for identifying parameters of a Volterra series model describing coupled non-linear distortion in a digital radar is explored and illustrated with simulated data.
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| 9. |
- Ma, Xiaohui, et al.
(author)
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Listener-Position Adaptive Crosstalk Cancelation Using A Parameterized Superdirective Beamformer
- 2018
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In: Proceedings of the IEEE Sensor Array and Multichannel Signal Processing Workshop. - 2151-870X. ; 2018-July, s. 114-118
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Conference paper (peer-reviewed)abstract
- We present a method for cancelation of the acoustic crosstalk between the ears of a listener using a linear loudspeaker array. This allows for controlling the signals that arise at listener's ear independently of each other so that binaural cues can be imposed. We employ superdirective near-field beamforming (SDB) over the vast part of the frequency range. Allowing the listener to move in front of the array requires the computation of a new SDB solution for each possible position of the listener, which is a computationally expensive procedure. We show that the beamformer weights exhibit a very smooth evolution for listening positions along a line parallel to the array. This makes it straightforward to parameterize pre-computed beamformer weights with a few parameters for each frequency. Upon realtime execution, the beamformer weights can be determined efficiently for any arbitrary position along the listener contour from the parameters with negligible error. Simulation results show that the proposed beamformer provides a higher channel separation than previously published solutions while maintaining robustness.
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| 10. |
- Malek Mohammadi, Mohammadreza, et al.
(author)
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DOA estimation in partially correlated noise using low-rank/sparse matrix decomposition
- 2014
-
In: 2014 IEEE 8th Sensor Array and Multichannel Signal Processing Workshop (SAM). - : IEEE Computer Society. - 9781479914814 ; , s. 373-376
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Conference paper (peer-reviewed)abstract
- We consider the problem of direction-of-arrival (DOA) estimation in unknown partially correlated noise environments where the noise covariance matrix is sparse. A sparse noise covariance matrix is a common model for a sparse array of sensors consisted of several widely separated subarrays. Since interelement spacing among sensors in a subarray is small, the noise in the subarray is in general spatially correlated, while, due to large distances between subarrays, the noise between them is uncorrelated. Consequently, the noise covariance matrix of such an array has a block diagonal structure which is indeed sparse. Moreover, in an ordinary nonsparse array, because of small distance between adjacent sensors, there is noise coupling between neighboring sensors, whereas one can assume that non-adjacent sensors have spatially uncorrelated noise which makes again the array noise covariance matrix sparse. Utilizing some recently available tools in low-rank/sparse matrix decomposition, matrix completion, and sparse representation, we propose a novel method which can resolve possibly correlated or even coherent sources in the aforementioned partly correlated noise. In particular, when the sources are uncorrelated, our approach involves solving a second-order cone programming (SOCP), and if they are correlated or coherent, one needs to solve a computationally harder convex program. We demonstrate the effectiveness of the proposed algorithm by numerical simulations and comparison to the Cramer-Rao bound (CRB).
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