共查询到20条相似文献,搜索用时 46 毫秒
1.
Li Q. Ilavarasan P. Ross J.E. Rothwell E.J. Kun-Mu Chen Nyquist D.P. 《Antennas and Propagation, IEEE Transactions on》1998,46(9):1272-1278
The E-pulse technique has been applied in the past to both the early- and the late-time components of a transient radar response. While the late-time E-pulse technique uses aspect-independent waveforms, the early-time E-pulse technique requires a separate waveform for each target aspect angle and thus significantly more storage and processing time. This paper discusses a combination of the two techniques that employs the early-time technique to remove ambiguities generated from application of the late-time method. By narrowing the possible range of aspect angles of the potential targets, the early-time technique can be employed more efficiently 相似文献
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Blanco D. Ruiz D.P. Alameda-Hernandez E. Carrion M.C. 《Antennas and Propagation, IEEE Transactions on》2006,54(5):1577-1585
The extinction pulse method has been proven to be a suitable method for radar target discrimination using the natural resonance annihilation concept. The standard procedure for extinction pulse (E-pulse) construction is based on an expansion on subsectional polynomials. In this paper it is proposed a new formalism for E-pulse construction using /spl beta/-splines. This formalism allows the E-pulse polynomial basis expansion to be treated in a unified theoretical framework and leads to a simplification of the original problem due to the linear nature of all the involved parameters. This new formulation has been also used to impose new conditions over the spectral contents of the E-pulses. These E-pulses constructed using the new conditions annihilate better the natural modes in the late-time radar target response, and provide a better discrimination rates than the classical scheme. 相似文献
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Bayard J.-P.R. Schaubert D.H. Rothwell E.J. Chen K.-M. Nyquist D.P. Sun W. 《Antennas and Propagation, IEEE Transactions on》1991,39(1):111-115
The performances of the optimization method and the extinction pulse method are evaluated for idealized data as well as experimental data from scaled-model targets. Although both methods use the late-time response to discriminate targets, the discriminant waveform is synthesized differently; from the target pole singularities in the E-pulse method, and from an energy maximization in the optimization method. Responses from waveforms synthesized using calculated wire data and laboratory measured data are presented, and the early-time energy confinements produced by the two methods are found to be generally comparable. The robustness of the optimization and E-pulse methods in the presence of noise is demonstrated by results for calculated and measured data 相似文献
5.
Baum C.E. Rothwell E.J. Chen K.-M. Nyquist D.P. 《Proceedings of the IEEE. Institute of Electrical and Electronics Engineers》1991,79(10):1481-1492
The singularity expansion method (SEM) for quantifying the transient electromagnetic (EM) scattering from targets illuminated by pulsed EM radiation is reviewed. SEM representations for both induced currents and scattered fields are presented. Natural-resonance-based target identification schemes, based upon the SEM, are described. Various techniques for the extraction of natural-resonance modes from measured transient response waveforms are reviewed. Particular attention is given to the aspect-independent (extinction) E-pulse and (single-mode) S-pulse discriminant waveforms which, when convolved with the late-time pulse response of a matched target, produce null or mono-mode responses, respectively, through natural-mode annihilation. Extensive experiment results for practical target models are included to validate the E-pulse target discrimination technique. Finally, anticipated future extensions and areas requiring additional research are identified 相似文献
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Blanco D. Ruiz D.P. Alameda E. Carrion M.C. 《Antennas and Propagation, IEEE Transactions on》2004,52(5):1348-1350
This communication proposes an E-pulse-based scheme for radar target discrimination that provides asymptotically correct results for any level of additive white noise contaminating the radar signal. After multiple sampling of the signal dispersed by the target, it is analytically shown that the cross correlation between the output signals of the E-pulse designed for the standard target, corresponding to two different sampling periods, is asymptotically , regardless of the amount of contaminating noise. The results obtained by simulation have allowed us to propose a discrimination criterion that produces better results than the original E-pulse technique at very low signal-to-noise ratio (SNR) levels. 相似文献
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《Antennas and Propagation, IEEE Transactions on》2009,57(2):444-451
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Radar target discrimination using the extinction-pulse technique 总被引:9,自引:0,他引:9
Rothwell E. Nyquist D. Kun-Mu Chen Drachman B. 《Antennas and Propagation, IEEE Transactions on》1985,33(9):929-937
An aspect independent radar target discrimination scheme based on the natural frequencies of the target is considered. An extinction-pulse waveform upon excitation of a particular conducting target results in the elimination of specified natural modal content of the scattered field. Excitation of a dissimilar target produces a noticeably different late-time response. Construction of appropriate extinction-pulse waveforms is discussed, as well as the effects of random noise on their application to thin cylinder targets. Also presented is experimental verification of this discrimination concept using simplified aircraft models. 相似文献
10.
An automated E-pulse scheme for target discrimination was initially presented by Ilavarasan et al. (1993) without an analytic performance evaluation. Assuming that target responses are contaminated with white Gaussian noise, an automated E-pulse scheme is rigorously analyzed to yield a reliable measure of performance. The discrimination performance of this automated E-pulse scheme is determined quantitatively through the use of energy discrimination numbers (EDNs). Statistics of the EDNs are evaluated analytically to derive the probability of correct identification. The probability of identification as a function of signal-to-noise ratio (SNR) is evaluated using the theoretical scattering data for all potential targets to predict the performance of the automated E-pulse scheme. These theoretical results are corroborated by direct simulation of the discrimination scheme. In addition, the probability density functions of the EDNs are presented providing new physical insights into E-pulse performance as a function of target geometries and SNR 相似文献
11.
Kun-Mu Chen Nyquist D. Rothwell E. Webb L. Drachman B. 《Antennas and Propagation, IEEE Transactions on》1986,34(7):896-904
A new method of radar target discrimination and identification is presented. This new method is based on the natural frequencies of the target. It consists of synthesizing aspect-independent discriminant signals, called extinction-pulses (E-pulses) and single-mode extraction signals which, when convolved numerically with the late-time transient response of an expected target, lead to zero or single-mode responses. When the synthesized, discriminant signals for an expected target are convolved with the radar return from a different target, the resulting signal will be significantly different from the expected zero or single-mode responses, thus, the differing targets can be discriminated. Theoretical synthesis of discriminant signals from known target natural frequencies and experimental synthesis of them for a complex target from its measured pulse response are presented. The scheme has been tested with measured responses of various targets in the laboratory. 相似文献
12.
In-Sik Choi Joon-Ho Lee Hyo-Tae Kim Rothwell E.J. 《Antennas and Propagation, IEEE Transactions on》2003,51(12):3285-3292
In this paper, we present a novel method for natural frequency extraction. Our algorithm is called late-time evolutionary programming (EP)-based CLEAN, and has many advantages compared to conventional methods. The accuracy of our algorithm is not affected by the false estimation of the number of natural resonance modes. Furthermore, our method is insensitive to random noise. Insensitivity is a very important characteristic in the resonance extraction algorithm since the late-time response usually has small energy. Using synthetic data, we show these characteristics by comparing them to Prony's method and the E-pulse technique. We also applied our method to the numerical data and B-52 measured data which is obtained at Michigan State University (MSU) arch range. 相似文献
13.
Savelyev T. G. van Kempen L. Sahli H. Sachs J. Sato M. 《Geoscience and Remote Sensing, IEEE Transactions on》2007,45(1):118-129
Ground-penetrating radar (GPR) is capable to detect plastic antipersonnel landmines as well as other subsurface targets. In order to reduce false alarms, an option of automatic landmine discrimination from neutral minelike targets would be very useful. This paper presents a possibility for such discrimination and analyzes it experimentally. The authors investigate time-frequency features of an ultrawideband (UWB) target response for the discrimination between buried landmines and other objects. The discrimination method includes the extraction of an early-time target impulse response, its time-frequency transformation, and the extraction of time-frequency features based on a singular value decomposition of the transformed image. In order to take into account the changes in the UWB target signals, the experimental conditions are completely controlled to focus on the behavior of the target's response with respect to its depth and the horizontal position of the GPR above it. The dependence of the features on the GPR bandwidth is analyzed as well. The Mahalanobis distance is used as a criterion for optimal discrimination. The obtained results define the best features and conditions when the landmine discrimination is successful. For comparison, the discriminant power of the proposed features has been tested on a dataset, acquired during a field campaign in Angola 相似文献
14.
The extinction pulse (E-pulse) technique has been widely applied to the problem of free-space radar target identification. In this paper, the possibility of applying the same E-pulse technique to a subsurface target recognition scheme is investigated. In particular, the detection of depth changes of a metallic target is considered with numerical examples that determine the depth of a hip prosthesis model buried inside representative human tissue. 相似文献
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Wavelet analysis of radar echo from finite-size targets 总被引:7,自引:0,他引:7
The wavelet analysis technique is applied to analyze the frequency-domain electromagnetic backscattered signal from finite-size targets. Since the frequency-domain radar echo consists of both small-scale natural resonances and large-scale scattering center information, the multiresolution property of the wavelet transform is well suited for analyzing such multiscale signals. Wavelet analysis examples of backscattered data from an open-ended waveguide cavity and a plasma cylinder are presented. Compared with the conventional short-time Fourier transform, the wavelet transform provides a more efficient representation of both the early-time scattering center data and the late-time resonances. The different scattering mechanisms are clearly resolved in the time-frequency representation 相似文献
16.
Morales J.D. Blanco D.. Ruiz D.P. Carrion M.C. 《Antennas and Propagation, IEEE Transactions on》2007,55(7):2064-2072
New contributions to noncooperative radar-target discrimination using only the scattered response of conductive objects are presented in this paper. The technique studied is the extinction-pulse (E-pulse), which makes use of natural resonances as discrimination features. The E-pulse expansion using complex exponential functions as basis functions is proposed, obtaining new E-pulses with characteristics completely different from those in the literature. Specifically, a weighting factor is added to modulate the exponential frequency, providing E-pulses with better discrimination capability. Numerical results achieved in the discrimination between thin straight wires of different lengths show that the proposed exponential E-pulses improve the discrimination results with respect to other types of E-pulses in the literature. 相似文献
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Adaptive arrays with main beam constraints 总被引:7,自引:0,他引:7
Initial applications of adaptive array theory to the radar sidelobe jamming problem ignored the problem of incidental cancellation of the desired signal returns. In more recent applications, longer transmitted waveforms have combined with returns from extended clutter and/or strong targets to create a more serious signal cancellation problem. There are several ways in which the adaptive processor can be constrained from responding to desired main lobe target returns while maintaining good cancellation of interference in the sidelobes. This paper examines the major techniques for constraining the response of the adaptive processor, including methods of controlling the response of the array in the absence of external interference. Time domain and frequency domain techniques are discussed. The majority of the discussion is devoted to angle domain techniques such as pilot signals, preadaption spacial filtering, and control loop spatial filtering. Analysis is presented showing the relationship between these techniques. Finally, examples are given showing the effects of these constraints as well as control of the quiescent array pattern. 相似文献
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S. P. Gavrilov A. A. Vertiy S. Samedov M. E. Özel 《Journal of Infrared, Millimeter and Terahertz Waves》1997,18(10):1967-1989
Time-domain response of a one-mode resonator is investigated by using a complex-exponential representation of the time-domain impulse response. The transient response of a resonator has calculated for a short incident pulse which has rectangular form and the radio frequency filling. The convolution integral has been analytically carried out and two solutions for the time histories of the transient response of the resonator have been found. They are the early-time and late-time portions of the signal. The behaviour of amplitude and frequency of the transient response of the electrodynamical structure under consideration is studied. 相似文献