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4th ieee sensor array and multichannel signal processing workshop

作者： Green, Justin W. Hale, Todd B. Temple, Michael A. Buckreis, John T. USAF Inst Technol Dept Elect & Comp Engn 2950 Hobson Way Wright Patterson AFB OH 45433 USA

ISBN: (纸本)1424403081

A technique is presented for incorporating pulse-to-pulse (inter-pulse) motion effects into side-looking array radar data models yielding a motion-sensitive space-time snapshot. Low flying, highly-maneuverable Unmanned Aerial Vehicles (UAV) represent a potential worst case application scenario given their roll, yaw, and pitch rates are primarily limited by structural integrity. High degrees of maneuverability during the Coherent processing Interval (CPI) allow clutter and target returns to change significantly. The technique presented uses M coordinate transformations to describe platform attitude variations throughout the CPI. Ward's model then is extended to incorporate maneuver-induced changes in spatial frequency and Doppler. The new motion-sensitive space-time snapshot is used to characterize Space Time Adaptive processing (STAP) performance without motion-compensation applied. Results clearly show motion-induced clutter-null broadening with measurable degradation of STAP algorithm minimal discernable velocity.

关键词： Radar systems

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sensor management with uncertain performance characteristics

Sensor management with uncertain performance characteristics

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4th ieee sensor array and multichannel signal processing workshop

作者： Kolba, Mark P. Collins, Leslie M. Duke Univ Elect & Comp Engn Dept Box 90291 Durham NC 27708 USA

ISBN: (纸本)1424403081

Previous work has presented an information-theoretic sensor management framework for the detection of static targets. This framework is based on the expected discrimination gain maximization technique of Kastella. The sensor manager searches for N targets within a grid of cells using M sensors, which may be thought of as a reconfigurable sensor array. sensor probabilities of detection and false alarm are used in the mathematical structure of the sensor manager, and these probabilities have previously been assumed to be certain. Realistic problems, however, will inevitably involve uncertainty. This paper introduces uncertain sensor P-d and P-f values into the mathematical framework and allows for their incorporation into the sequential structure of the sensor manager. The performance of the presented sensor management technique is then compared to direct search, where the sensors sweep through the grid in a predefined sampling pattern. The sensor manager is found to be superior to direct search when the uncertainty present in the problem is properly modeled. When uncertainty is present but not modeled, the performance of the sensor manager is severely degraded. This result indicates that uncertainty modeling will be important and necessary for the successful application of the presented sensor manager to real-world problems. Additional simulations examine the robustness of the sensor manager to errors in the assumed densities for P-d and P-f, and the performance of the sensor manager is found to remain strong even when the assumed P-d and P-f densities differ from the true densities.

关键词： sensor management discrimination gain uncertainty detection multimodal sensing

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Performance analysis of linear predictive super-resolution processing for antenna arrays

Performance analysis of linear predictive super-resolution p...

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4th ieee sensor array and multichannel signal processing workshop

作者： Chen, Honglei Kasilingam, Dayalan Univ Massachusetts Dept Elect & Comp Engn N Dartmouth MA 02747 USA

ISBN: (纸本)1424403081

Many applications in array processing require a high resolution beamforming method. For example, Spatial Division Multiple Access (SDMA) has been proposed to achieve higher system capacity in wireless systems. Implicit in SDMA is the ability to adaptively generate narrow antenna beam patterns, which ensures the physical separation between users and minimizes multiple user interference. However, antenna theory requires large antenna apertures to generate narrow beam patterns. This paper discusses an adaptive algorithm for extrapolating measurements from a small antenna array to a much larger virtual array. The technique utilizes linear prediction (LP) methods to perform the extrapolation. A Least Mean Square (LMS) based algorithm was used to estimate the LP coefficients. Since the algorithm is linear, it serves both as a direction-of-arrival (DoA) estimator and a matched filter for retrieving the transmitted signal. Other popular high-resolution algorithms such as MUSIC are inherently nonlinear and thus cannot be used on their own for retrieving signal information. The performance of this algorithm is studied with respect to interference suppression, noise and spatial resolution. It is shown that the IIR filter representing the LP process has poles corresponding to the DoA of the signal. The resulting LP coefficients can eliminate the interference between signals from different transmitters. However, no improvement in noise performance is seen because the receiver noise couples into the extrapolation process when two transmitters are closely located. The extrapolation algorithm is compared with the LCMV algorithm and found to produce similar results.

关键词： array processing

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Extreme beam broadening using phase only pattern synthesis

Extreme beam broadening using phase only pattern synthesis

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4th ieee sensor array and multichannel signal processing workshop

作者： Brown, George C. Kerce, J. Clayton Mitchell, Mark A. Georgia Inst Technol Georgia Tech Res Inst Sensors & Electromagnet Applicat Lab Atlanta GA 30332 USA

ISBN: (纸本)1424403081

This paper describes methods for broadening the beam of a phased array antenna using phase-only element weights. This type of broadening can be valuable for improving the search occupancy and/or reducing the search frame time for large phased arrays, when transmit beam broadening is combined with multiple simultaneous receive beams. Phase-only broadening is required for typical solid-state (active phased) arrays because control of the transmit amplitude at each element is not practical. A notable result is that there is a relationship between the amount of beam broadening and the efficiency (directivity) of the resulting beam. In particular it is shown that broadening less than similar to 2.5:1 results in reduced beam efficiency for both linear and circular arrays, while a broadening of greater than similar to 2.5:1 results in improved beam efficiency, and that, therefore, certain broadening configurations will be preferable to the radar designer (e.g. 4:1 in one plane rather than 2:1 in two planes, due to a large difference in efficiency). The algorithms used to achieve the broadening patterns presented here are based on a combination of homotopy from known optimality with a stochastic gradient descent approach using a carefully constructed one parameter family of penalty functions.

关键词： pattern synthesis wideband array processing transmit spoiling null control

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Model for a smart network monitoring a wired sensor matrix

Model for a smart network monitoring a wired sensor matrix

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4th ieee sensor array and multichannel signal processing workshop

作者： Magagni, Luca Gennaretti, Davide Nicolini, Matteo Sergio, Maximilian Guerrieri, Roberto Canegallo, Roberto Univ Bologna ARCES I-40126 Bologna Italy STMicroelect FTM Agrate Brianza Italy

ISBN: (纸本)1424403081

Monitoring harsh environments such as underwater scenarios or aircraft external surfaces pertains to important applications like assisted navigation and tactical surveillance;nevertheless, it poses additional challenges compared with standard applications. At Transducers2005 we presented a wired addressing architecture of distributed sensors for monitoring real-time in-situ pressure variations in underwater environment that faces the above-mentioned issues. This architecture consists in a double array of identical and interconnected smart nodes monitoring a matrix of passive sensors. I n this paper, we present an analysis of the delay model related to the presented architecture and a calculation of the overall frame-rate of the system as a function of the geometrical topology of the arrays. The topology of the network, i.e. the length of each bus and the number of nodes, can be chosen according to the application, and directly affects the global capacitive load on the serial lines. Each serial line can be schematized with a distributed RC model for the flat cable plus a lumped capacitance for each smart node. Then, a 3(rd)-order pi-segmented model of O'Brien-Savarino [4] is calculated for a 16-block fine with block length equal to 0.3m. Thanks to that, the global time per iteration is calculated on each bus as well as the scanning time of the whole matrix and the frame rate for the system as a function of sensor distribution and of the aspect ratio of the matrix. This model can be employed to identify the optimal arrangement for the sensor matrix and smart node arrays.

关键词： Intelligent networks

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Forward-looking planar array 3D-STAP using space time illumination patterns (STIP)

Forward-looking planar array 3D-STAP using space time illumi...

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4th ieee sensor array and multichannel signal processing workshop

作者： Corbell, Phillip M. Temple, Michael A. Hale, Todd B. SNHE Air Force Res Lab Hanscom AFB MA 01731 USA ENG Air Force Inst Technol Wright Patterson AFB OH USA

ISBN: (纸本)1424403081

Close-in sensing is needed for urban warfare operations, where Ground Moving Target Indication (GMTI) could be provided via forward or rear-facing multi-function array radars mounted on small highly-maneuverable airborne platforms. However, airborne radar arrays oriented any direction other than side-looking cause an elevation dependent angle-Doppler relationship in the clutter returns. This non-stationarity is acute in close-in sensing geometries where elevation diversity exists over the scene of interest. However, planar arrays have an inherent advantage over linear arrays due to their ability to observe clutter statistics as a function of elevation. This paper demonstrates the utility of elevation diversity by synthesizing a single 3D-STAP filter that exhibits an elevation dependent azimuth-Doppler response which is tailored to null the clutter "bowl" which characterizes the forward-looking clutter spectrum. Such a capability is particularly exploitable on transmit, where all elevation angles are simultaneously illuminated. To demonstrate potential benefits, this paper proposes the use of recently developed Space Time Illumination Patterns (STIP) from a planar AESA to invoke elevation diverse space-time illumination in a forward-looking clutter scenario. It is shown that 3D-STIP (azimuth-elevation-Doppler) facilitates elevation specific space-time beamforming which removes the clutter energy from a given Doppler frequency across all ranges, potentially simplifying processing on receive. Simulations using synthesized training data and clairvoyant covariance knowledge are conducted to demonstrate proof-of-concept.

关键词： Radar systems

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signal strength localization bounds in ad hoc & sensor networks when transmit powers are random

Signal strength localization bounds in ad hoc & sensor netwo...

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4th ieee sensor array and multichannel signal processing workshop Proceedings, SAM 2006

作者： Patwari, Neal Hero III, Alfred O. Department of Electrical Engineering and Computer Science University of Michigan Ann Arbor MI United States

ISBN: (纸本)1424403081

sensor localization bounds have been derived assuming that received signal strength (RSS) measurements are performed with perfectly known sensor transmit powers. In this paper the Bayesian Cramér-Rao bound is derived assuming transmit powers are random with known prior distribution. Further, both directional measurements on each link, from i to j and from j to i, and their correlation, are explicitly considered. Results show that random transmit powers have a small (5-13%) impact on coordinate estimation bounds. However, using only the average of the directional measurements can significantly increase these bounds. © 2006 ieee.

关键词： signal analysis

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Improved Direction-of-Arrival estimation using wavelet based denoising techniques

Improved Direction-of-Arrival estimation using wavelet based...

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14th ieee International workshop on Machine Learning for signal processing

作者： Sathish, R. Anand, G. V. EPFL Biomed Imaging Grp STI LIB ECUBLENS CH-1015 Lausanne Switzerland Indian Inst Sci Dept Elect Commun Engn Bangalore 560012 Karnataka India

In this paper, we explore the use of wavelet based denoising techniques to improve the Direction-of-Arrival (DOA) estimation performance of array processors at low SNR. Traditional single sensor wavelet denoising techniques are not suitable for this application since they fail to preserve the intersensor signal correlation. We propose two correlation preserving techniques for denoising multi-sensor signals: (1) the Temporal Wavelet array Denoising (TWAD) technique developed by Rao and Jones [ieee Trans. signal processing, vol. 48, pp. 1225-1234, 2000], and (2) a new Spatial Wavelet array Denoising (SWAD) technique. It is shown that SWAD offers the advantage of a significant reduction in computational complexity at the cost of a slight reduction in SNR gain. The denoised array data is used for DOA estimation by the MUSIC algorithm. Simulation results are presented for MUSIC (without denoising), TWAD-MUSIC, and SWAD-MUSIC, to illustrate the improvement in DOA estimation performance brought about by denoising.

关键词： Direction-of-Arrival (DOA) estimation Temporal Wavelet array Denoising (TWAD) Spatial Wavelet array Denoising (SWAD)

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2006 ieee SAM - workshop Committees

2006 IEEE SAM - Workshop Committees

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sensor array and multichannel signal processing workshop

Provides a listing of current committee members.

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Noncooperative iterative MMSE beamforming algorithms for ad hoc networks

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ieee TRANSACTIONS ON COMMUNICATIONS 2006年第4期54卷 748-759页

作者： Iltis, RA Kim, SJ Hoang, DA Univ Calif Santa Barbara Dept Elect & Comp Engn Santa Barbara CA 93106 USA

An asynchronous unicast ad hoc network is considered, where each node i is equipped with a receive/transmit beamformer pair (w(i), g(i)) designed under a quality-of-service (QoS) SNR constraint. It is first shown that the minimum sum-power beamformers for the network satisfy a weak duality condition, in which the pairs ((g(i)(opt))*, (w(i)(opt))*) achieve the same sum power as the primal network. However, the optimum receive beamformer w(i)(opt) is not in general equal to (g(i)(opt))*, in contrast to the case of cellular and time-division duplexing networks. Iterative minimum mean-square error (IMMSE) beamforming algorithms are then proposed in which w(i) = g(i)* is enforced. These algorithms are shown to be instances of the Power Algorithm in which gi is the maximizing eigenvector of an SNR-related objective matrix. The IMMSE algorithm can also be viewed as a noncooperative beamforming game, in which the payoff includes normalized SNR, and the tax is related to interference caused at other nodes. The existence of fixed points (Nash equilibria) is proved for IMMSE. Furthermore, fixed points of IMMSE are shown to satisfy the first-order necessary conditions for optimization using a network Lagrangian. The IMMSE game is modified to yield a sequential distortionless-response beamforming algorithm, which is shown to be convergent using a Total Interference Function. Extensive simulation results illustrate that IMMSE yields better power efficiency than a greedy noncooperative SNR-maximizing game.

关键词： array signal processing game theory least-mean-square (LMS) methods networks

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