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Sylvie Marcos - One of the best experts on this subject based on the ideXlab platform.

  • Adaptive Processing methods for MIMO radar experimental signals
    2014
    Co-Authors: Mathieu Cattenoz, Laurent Savy, Sylvie Marcos
    Abstract:

    MIMO radar is a promising concept and many theoretical studies have demonstrated its interest. The colored transmission makes it possible to extract each waveform and form the transmission beam by digital Processing on receive.One strong limitation of this technique is that waveforms cannot be perfectly separated in practice, because of the intrinsic lack of orthogonality of the waveforms family or hardware defaults. In case of conventional radar Processing, this badly impacts the performance on target detection and localization. In this paper, we explain in which way the usual approach of adapted filter is not adapted for MIMO radar signals. Then, we introduce different approaches to estimate the target amplitude based on Adaptive Processing, and we deal with their performance and limitations when applied in the context of non perfectly orthogonal waveforms.We especially focus on Orthogonal Matching Pursuit (OMP) procedure which aims at detecting and cleaning each target, successively. We point out the problematic effects due to the granularity of the target amplitude grid and neighbor targets influence. To solve the problem, we propose, at each step of the OMP procedure, not only to clean the estimated position of the target, but also the close neighbor positions.We demonstrate that this “extended rejection” increases the robustness of OMP on realistic MIMO waveforms. Eventually, we apply and compare the classical, IAA (Iterative Adaptive Approach) and OMP approaches on experimental MIMO signals.

  • Adaptive Processing for MIMO radar realistic non perfectly orthogonal waveforms
    2014
    Co-Authors: Mathieu Cattenoz, Sylvie Marcos
    Abstract:

    MIMO radar is a promising concept and many theoretical studies have demonstrated its interest, especially for possible improvements in term of target detection and localization. The colored transmission makes it possible to extract each waveform and form the transmission beam by digital Processing on the reception side. One strong limitation of this technique is that waveforms cannot be perfectly separated in practice, because of the intrinsic lack of orthogonality of the waveforms family or hardware defaults. In case of conventional radar Processing, this badly impacts the performance on target detection.In this paper, we introduce another approach to perform the estimation of target detection and localization based on Adaptive Processing such as Capon estimation. We define the techniques especially for MIMO radar configurations and we use them on realistic signals, taking into account the properties of non perfect orthogonality of the transmitted MIMO waveforms. We compare the results of the different methods to establish to which extent the performance in target detection can be improved. In some conditions, all sidelobes can be suppressed.

  • A Riemannian approach for training data selection in space-time Adaptive Processing applications
    2013
    Co-Authors: Jean-françois Degurse, Sylvie Marcos, Laurent Savy, Jean-philippe Molinié
    Abstract:

    Heterogeneous situations are a serious problem for Space-Time Adaptive Processing (STAP) in an airborne radar context. Indeed, STAP detectors need secondary training data that have to be homogeneous with the tested data, otherwise the performances of these detectors are severely impacted when facing heterogeneous environments. Hence, training data have to be carefully selected and this is traditionally done in Euclidean geometry. We introduce a new criterion for data selection. We show that it can be viewed as an approximation of the metric distance in Riemannian geometry.

  • An extended formulation of the maximum likelihood estimation algorithm. Application to space-time Adaptive Processing
    2011
    Co-Authors: Jean-françois Degurse, R. Perenon, Laurent Savy, Sylvie Marcos
    Abstract:

    This paper proposes an extended version of the Maximum Likelihood Estimation Detector (MLED) that can operate in severe heterogeneous environment for slow moving target detection in ground clutter using space-time Adaptive Processing (STAP). Unlike the MLED, the extended version called STOP-BAND APES does not suffer from the high Doppler resolution properties of the MLED leading to severe extra computational burden. Performances are illustrated on realistic synthetic data.

  • Range recursive and Taylor series based space-time Adaptive Processing for range dependent clutter rejection
    2011
    Co-Authors: Sylvie Marcos, Sophie Beau
    Abstract:

    This paper presents a new space time Adaptive Processing (STAP) for the rejection of range dependent ground clutter in order to detect slow moving targets with an airborne radar. STAP usually requires the estimation of the clutter plus noise covariance matrix from secondary data neighboring the cell under test. However, in most radar antenna array architectures and/or configurations which are different from the conventional uniform linear antenna array and side-looking configuration the clutter is range dependent. We recently proposed the use of a Taylor series expansion of the clutter plus noise subspace in conjunction with the eigencanceler-based (EC) STAP in order to mitigate the range non-stationarity of the clutter. In this paper, the computationally costly EC is replaced by a range-recursive algorithm which is capable of tracking non stationarities with a reduced complexity compared to the EC. The performance of the proposed algorithm is satisfactorily tested and compared to other algorithms in the case of a bistatic configuration.

Michael C Wicks - One of the best experts on this subject based on the ideXlab platform.

  • Knowledge based Adaptive Processing for ground moving target indication
    Digital Signal Processing, 2007
    Co-Authors: Raviraj S Adve, T.b. Hale, Michael C Wicks
    Abstract:

    This paper presents a preliminary knowledge based approach to space-time Adaptive Processing (STAP) for ground moving target indication from an airborne platform. The KB-processor accounts for practical aspects of Adaptive Processing, including detection and Processing of non-homogeneous data, appropriate selection of training data, and accounting for array effects such as mutual coupling and channel mismatch. In combining these hitherto separate STAP issues into a unified approach, this paper furthers the move of STAP from theory to practice. The KB-approach is tested using measured data from the multi-channel airborne radar measurements (MCARM) program.

  • space time Adaptive Processing a knowledge based perspective for airborne radar
    IEEE Signal Processing Magazine, 2006
    Co-Authors: Michael C Wicks, Raviraj S Adve, Muralidhar Rangaswamy, T.b. Hale
    Abstract:

    This article provides a brief review of radar space-time Adaptive Processing (STAP) from its inception to state-of-the art developments. The topic is treated from both intuitive and theoretical aspects. A key requirement of STAP is knowledge of the spectral characteristics underlying the interference scenario of interest. Additional issues of importance in STAP include the computational cost of the Adaptive algorithm as well as the ability to maintain a constant false alarm rate (CFAR) over widely varying interference statistics. This article addresses these topics, developing the need for a knowledge-based (KB) perspective. The focus here is on signal Processing for radar systems using multiple antenna elements that coherently process multiple pulses. An Adaptive array of spatially distributed sensors, which processes multiple temporal snapshots, overcomes the directivity and resolution limitations of a single sensor.

  • Demonstration of knowledge-aided space-time Adaptive Processing using measured airborne data
    IEE Proceedings - Radar Sonar and Navigation, 2006
    Co-Authors: C.t. Capraro, Gerard T. Capraro, A. De Maio, Alfonso Farina, Michael C Wicks
    Abstract:

    The design and analysis of a knowledge-aided detector for airborne space-time Adaptive Processing (STAP) applications are addressed. The proposed processor is composed of a training data selector, which chooses secondary cells best representing the clutter statistics in the cell under test, and an Adaptive processor for detection Processing. The data selector is a hybrid algorithm, which pre-screens training data through the use of terrain information from the United States Geological Survey. Then, in the second stage, a data-driven selector attempts to eliminate residual non-homogeneities. The performance of this new approach is analysed using measured airborne radar data, obtained from the multi-channel airborne radar measurements program, and is compared with alternative STAP detectors proposed in the open literature.

  • Pre-filtering for clutter rejection in beamspace STAP
    IEEE International Radar Conference 2005., 2005
    Co-Authors: M. Khanpour-ardestani, Raviraj S Adve, Michael C Wicks
    Abstract:

    Several space-time Adaptive Processing algorithms have been proposed to detect weak targets in the presence of strong interference, especially clutter and jamming. Except for displaced phase center array (DPCA) Processing, radar signal Processing algorithms ignore the fact that the location of the clutter ridge in angle-Doppler space is known, given the platform speed and direction. This paper introduces our attempt to exploit this a priori knowledge in conjunction with the joint domain localized Processing algorithm. Using a two-dimensional filter, clutter is rejected in a first, non-Adaptive stage, followed by Adaptive Processing in the angle-Doppler domain.

  • A Comprehensive Multidisciplinary Program for Space-Time Adaptive Processing (STAP)
    2005
    Co-Authors: Tapan K. Sarkar, Michael C Wicks
    Abstract:

    Abstract : The purpose of this effort was to perform focused research in the theory and strategies for space-time Adaptive Processing (STAP) in radar systems. The objective was to detect low flying targets in a severe clutter and jamming environment in real time. This was accomplished for Air Borne Radars by implementing two-dimensional Adaptive filtering techniques in space (angle domain) and in time (Doppler domain) on High Performance Parallel computers. The initial simulations were carried out on the Maui HPCC.

Sophie Beau - One of the best experts on this subject based on the ideXlab platform.

  • Range recursive and Taylor series based space-time Adaptive Processing for range dependent clutter rejection
    2011
    Co-Authors: Sylvie Marcos, Sophie Beau
    Abstract:

    This paper presents a new space time Adaptive Processing (STAP) for the rejection of range dependent ground clutter in order to detect slow moving targets with an airborne radar. STAP usually requires the estimation of the clutter plus noise covariance matrix from secondary data neighboring the cell under test. However, in most radar antenna array architectures and/or configurations which are different from the conventional uniform linear antenna array and side-looking configuration the clutter is range dependent. We recently proposed the use of a Taylor series expansion of the clutter plus noise subspace in conjunction with the eigencanceler-based (EC) STAP in order to mitigate the range non-stationarity of the clutter. In this paper, the computationally costly EC is replaced by a range-recursive algorithm which is capable of tracking non stationarities with a reduced complexity compared to the EC. The performance of the proposed algorithm is satisfactorily tested and compared to other algorithms in the case of a bistatic configuration.

  • Taylor series expansions for airborne radar space-time Adaptive Processing
    IET Radar Sonar and Navigation, 2011
    Co-Authors: Sophie Beau, Sylvie Marcos
    Abstract:

    Space time Adaptive Processing (STAP) for range dependent clutter rejection in airborne radar is considered. Indeed, radar antenna architectures or configurations which are different from the conventional uniform linear antenna array (ULA) and side-looking configuration have consequences on the clutter properties. We here investigate the use of Taylor series expansions of the space-time covariance matrix in the classical sample matrix inversion (SMI) STAP method in order to mitigate the range non-stationarity of the clutter and we compare it to the Derivative Based Updating (DBU) already proposed in the literature. We also propose a new algorithm based on a Taylor series expansion of the interference plus noise subspace in conjunction with the eigencanceler-based (EC) STAP, which improves the performance in term of SINR loss, compared to the DBU method. In this paper, the particular cases of a ULA in a non side-looking configuration and a uniform circularly curved antenna (UCCA) array in side-looking and non side-looking configurations are considered for the test and the comparison of the presented algorithms.

  • Range dependent clutter rejection using range recursive space-time Adaptive Processing (STAP)
    Signal Processing, 2010
    Co-Authors: Sophie Beau, Sylvie Marcos
    Abstract:

    This paper adresses the issue of ground clutter rejection for the detection of slowly moving targets in a non side looking (NSL) array configuration airborne radar. The optimum Space Time Adaptive Processing (STAP) filter needs the knowledge of the inverse of the space-time covariance matrix. In practice, it is unknown and has to be estimated. The most popular approximated method is the Sample Matrix Inversion (SMI) method which consists in inverting the covariance matrix estimated by an average of the sample matrix over the secondary range cells. This estimator is unbiased in case of i.i.d. data. In a NSL configuration, the clutter power spectrum is range dependent and the data are consequently not i.i.d.. We here present a solution to mitigate this range dependency of the data : the range recursive subspace-based algorithms. They are used in two architectures: a fully and a partially Adaptive ones. Then a new range recursive algorithm using Taylor series expansion is investigated. The performance of these algorithms are compared with that of the conventional STAP algorithms in term of SINR loss.

Raviraj S Adve - One of the best experts on this subject based on the ideXlab platform.

  • Two-dimensional Adaptive Processing for ionospheric clutter mitigation in High Frequency Surface Wave Radar
    2009 IEEE Radar Conference, 2009
    Co-Authors: Ryan J. Riddolls, Raviraj S Adve
    Abstract:

    High Frequency Surface Wave Radar (HFSWR) is a technology used for over-the-horizon detection of ocean vessels. This radar exploits the diffraction of electromagnetic waves around the curved surface of the Earth. To minimize the attenuation of the diffracted waves, the radar must operate at frequencies in the lower part of the high frequency (HF) band. However, radar signals at these frequencies also reflect from the Earth's ionosphere, which leads to radar clutter at ranges beyond 200 km. The linear broadside receive arrays used by conventional HFSWR systems cannot filter out this clutter as the arrays do not have any resolving power in elevation angle. Reported here are experimental investigations of the clutter suppression capability of one- and two-dimensional HFSWR Adaptive processors. Three configurations are compared: one-dimensional spatial Adaptive Processing, two-dimensional spatial Adaptive Processing, and space-time Adaptive Processing. In all cases the number of Adaptive degrees of freedom is 16. It is found that the best results are achieved by two-dimensional spatial Adaptive Processing, where a Processing gain of up to about 20 dB can be achieved.

  • Knowledge based Adaptive Processing for ground moving target indication
    Digital Signal Processing, 2007
    Co-Authors: Raviraj S Adve, T.b. Hale, Michael C Wicks
    Abstract:

    This paper presents a preliminary knowledge based approach to space-time Adaptive Processing (STAP) for ground moving target indication from an airborne platform. The KB-processor accounts for practical aspects of Adaptive Processing, including detection and Processing of non-homogeneous data, appropriate selection of training data, and accounting for array effects such as mutual coupling and channel mismatch. In combining these hitherto separate STAP issues into a unified approach, this paper furthers the move of STAP from theory to practice. The KB-approach is tested using measured data from the multi-channel airborne radar measurements (MCARM) program.

  • space time Adaptive Processing a knowledge based perspective for airborne radar
    IEEE Signal Processing Magazine, 2006
    Co-Authors: Michael C Wicks, Raviraj S Adve, Muralidhar Rangaswamy, T.b. Hale
    Abstract:

    This article provides a brief review of radar space-time Adaptive Processing (STAP) from its inception to state-of-the art developments. The topic is treated from both intuitive and theoretical aspects. A key requirement of STAP is knowledge of the spectral characteristics underlying the interference scenario of interest. Additional issues of importance in STAP include the computational cost of the Adaptive algorithm as well as the ability to maintain a constant false alarm rate (CFAR) over widely varying interference statistics. This article addresses these topics, developing the need for a knowledge-based (KB) perspective. The focus here is on signal Processing for radar systems using multiple antenna elements that coherently process multiple pulses. An Adaptive array of spatially distributed sensors, which processes multiple temporal snapshots, overcomes the directivity and resolution limitations of a single sensor.

  • Pre-filtering for clutter rejection in beamspace STAP
    IEEE International Radar Conference 2005., 2005
    Co-Authors: M. Khanpour-ardestani, Raviraj S Adve, Michael C Wicks
    Abstract:

    Several space-time Adaptive Processing algorithms have been proposed to detect weak targets in the presence of strong interference, especially clutter and jamming. Except for displaced phase center array (DPCA) Processing, radar signal Processing algorithms ignore the fact that the location of the clutter ridge in angle-Doppler space is known, given the platform speed and direction. This paper introduces our attempt to exploit this a priori knowledge in conjunction with the joint domain localized Processing algorithm. Using a two-dimensional filter, clutter is rejected in a first, non-Adaptive stage, followed by Adaptive Processing in the angle-Doppler domain.

  • Joint domain localized Adaptive Processing for CDMA systems
    2004 IEEE 59th Vehicular Technology Conference. VTC 2004-Spring (IEEE Cat. No.04CH37514), 2004
    Co-Authors: R Wong, Raviraj S Adve
    Abstract:

    An effective approach to increase system capacity would be combining space division multiple access (SDMA) with other multiple access approaches such as code division multiple access (CDMA). However, implementing such a system requires interference cancellation to separate users' signals spatially and/or temporally. In this regard, an integrated beamforming (spatial Processing) and multiuser detection (temporal Processing) scheme outperforms all linear Processing schemes, but is also impractical due to the high computational costs. Other researchers have proposed some more practical reduced-rank or iterative schemes. This paper introduces a joint domain Adaptive algorithm which processes spatial and temporal data within a localized region in beamspace. This new algorithm is developed for uplink CDMA systems with multiple receive antennas. The simulations show that this approach is more effective than the reduced rank and iterative schemes in suppressing interference at significantly lower computational cost.

Zhengguang Zhou - One of the best experts on this subject based on the ideXlab platform.

  • ICASSP - Space-time-range three dimensional Adaptive Processing
    2009 IEEE International Conference on Acoustics Speech and Signal Processing, 2009
    Co-Authors: Shengqi Zhu, Guisheng Liao, Zhengguang Zhou
    Abstract:

    Space-time Adaptive Processing (STAP) is an effective tool for moving target detection. Conventional STAP methodologies process the angular and Doppler two dimensional data vector. In practical applications, adjacent range cells are statistically dependent due to filtering, since the point spreading function of a target is not an ideal delta function. In this paper, a novel approach incorporating range (fast time) information in STAP is presented for clutter rejection, which we term space-time-range Adaptive Processing (STRAP). This method takes advantage of the correlation information of neighboring range cells. Therefore, the stationary clutter can be suppressed better compared with traditional STAP algorithms ignoring fast time information, resulting in more effective moving target detection. The validity of the STRAP algorithm is verified by the experiments of Processing the real measured data of the three-channel X-band radar and MCARM radar systems.