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Radar Conference, 2003. Proceedings of the 2003 IEEE

Date 5-8 May 2003

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Displaying Results 1 - 25 of 74
  • FOPEN scene generation using numerical electromagnetic analysis

    Page(s): 362 - 369
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (479 KB) |  | HTML iconHTML  

    This work develops the high-fidelity simulation capability for foliage penetration (FOPEN) synthetic aperture radar (SAR). The simulation is based on a method of moments (MOM) numerical electromagnetic analysis of target scenes including foliage. The ability to accurately model the interaction of foliage and target is crucial for an accurate simulation. Example scenes for isolated metal targets are provided in addition to scenes with dielectric and combined metal and dielectric targets. As expected, the effect of the surrounding foliage is shown to have a significant impact on the reconstructed target image. This approach will be useful in FOPEN applications for the prediction of target signatures under various conditions of concealment. View full abstract»

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  • High fidelity modeling of space-based radar

    Page(s): 185 - 191
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (648 KB) |  | HTML iconHTML  

    Space based radar design are becoming more affordable given new technologies of solid state active apertures and advanced digital signal processing. However, it is important to be able to synthesize the design of the system with sufficient detail to anticipate the radar system's operation and interference effects expected in a space environment. This includes simulation of site specific clutter with realistic Earth rotation and statistical variation, wideband propagation of the signal from multiple phase center aperture, and impact of channel match and errors on adaptive processing for detecting targets. The research laboratory space time adaptive processing (RLSTAP) has been developed as a variable fidelity radar simulation tool to captures these effects. The paper will describe results of modeling an L-band multimode space based radar, including effective of ambiguities from antenna subarrays, and range and Doppler waveforms on adaptive processing. View full abstract»

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  • Design of large space based radar for multimode surveillance

    Page(s): 1 - 6
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (465 KB) |  | HTML iconHTML  

    Space based radars have been under consideration for several years [Skolnik, MI, 1997], and have only been made commercially available for synthetic aperture radar modes. This is due to the limited availability of space based microwave technologies and the high cost of manufacturing large space systems. Several technology programs have promised significant advances in affordable phased array radar designs. However, the design of true multimode radars require aperture sizes and average power significantly larger than previously considered. This paper outlines a design approach that anticipates future developments of ultra lightweight antenna manufacturing techniques. Based on a notional design, the performance predictions and challenges to radar signal processing is presented. View full abstract»

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  • Multi-channel signal subspace processing methods for SAR-MTI

    Page(s): 126 - 132
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (467 KB) |  | HTML iconHTML  

    This paper examines coherent signal processing methods for combining the data that are collected via multi-channel airborne radar system for MTI/GMTI. We study the methods that convert multi-channel radar data into dual along-track monopulse SAR signals of the radiated scene. A 2D adaptive filtering method, that projects the data in one synthesized SAR channel into the signal subspace of the other, is used for blind calibration of the monopulse SAR signals and generation of the MTI statistic. The merits of these algorithms are studied using the data from the multi-channel airborne radar measurement (MCARM) system that has been developed by the Air Force Research Laboratory at Rome, New York. View full abstract»

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  • Beam control using the parametric adaptive matched filter STAP approach

    Page(s): 405 - 412
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (466 KB) |  | HTML iconHTML  

    This paper evaluates the performance of a vector autoregressive space-time adaptive processing method, the parametric adaptive matched filter (PAMF), in the presence of airborne radar clutter and white noise interference. Performance metrics are derived from a PAMF weight vector representation and include the detection test statistic, the signal-to-interference-plus-noise ratio, and the adapted angle-Doppler beam pattern. Results are shown for the latter metric in the presence of mainbeam and closely spaced sidelobe interference. View full abstract»

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  • Exploiting persymmetry for CFAR detection in compound-Gaussian clutter

    Page(s): 110 - 115
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (427 KB) |  | HTML iconHTML  

    This paper deals with the problem of estimating the covariance structure of a compound-Gaussian process and of its application to adaptive radar detection in clutter-dominated disturbance. The proposed estimator exploits the persymmetry property typical of Toeplitz covariance matrices and is based on secondary data, free of signal components, and with the same covariance structure of the cell under test. We prove that, plugging the proposed covariance estimator into the normalized matched filter (NMF) [E. Conte, M. Lops, and G. Ricci, 1995], leads to an adaptive detector which, irrespective of the shape of the clutter power spectral density (psd), ensures the constant false alarm rate (CFAR) property with respect to both the clutter covariance matrix as well as the statistics of the texture. Finally, we show that this adaptive receiver has an acceptable loss with respect to its non-adaptive counterpart and outperforms the previously proposed CFAR adaptive NMF (ANMF) [E. Conte, A de Maio, and G. Ricci, 2002]. View full abstract»

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  • Medium PRF radar PRF optimisation using evolutionary algorithms

    Page(s): 192 - 197
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (748 KB) |  | HTML iconHTML  

    In this paper we employ evolutionary algorithms for the selection of optimal pulse repetition frequency (PRF) sets to minimise range-Doppler blindness in a model of a medium PRF radar. Both eight and nine PRF schedules are considered and the algorithm ensures that all the solutions produced are fully decodable and have no blind velocities. We consider the detailed effects of side-lobe clutter and the many technical factors affecting the choice of radar PRF in a medium PRF mode of operation of a practical airborne fire control radar. View full abstract»

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  • A novel method for improving the real-time of multitarget-multisensor tracking system

    Page(s): 223 - 227
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (301 KB) |  | HTML iconHTML  

    Since multitarget-multisensor tracking system can effectively fuse all kinds of information came from all kinds of sensors, this tracking system can more correctly track targets and widely interpret their state than any single tracking system does. But the real-time the multitarget-multisensor tracking system is not very good. In this paper, a novel method is presented, which is to improve the real-time of the multitarget-multisensor tracking system by optimizing the performance of the tracking gate method. Finally, the simulation shows that this method can effectively improve the real-time of multitarget-multisensor tracking system, especially in a heavy clutter and/or false alarm environment. View full abstract»

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  • Hovering helicopter measured by bi-/multistatic CW radar

    Page(s): 165 - 170
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (582 KB) |  | HTML iconHTML  

    The use of bi-/multistatic radar to detect and extract parameters for classification of a hovering helicopter has been studied. An experimental continuous wave bistatic radar has been used in a series of measurements covering a range of bistatic geometries. Variations in detection of rotor tip velocity, number of blades of main and tail rotor and direction of Doppler shift is observed. The use of a series of bistatic receiver pairs (multistatic radar) will increase the ability to extract characteristic parameters that would enhance classification. View full abstract»

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  • Detection improvements with CFARs having expanded amplitude inputs

    Page(s): 116 - 120
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (347 KB)  

    This paper addresses some differences in performance of cell averaging, constant false alarm rate (CA-CFAR) processors as a function of whether the input signal has linear, square-law, or a higher order response relative to the output of a linear receiver. For brevity, these CFAR inputs are herein referred to as A, A2, A4, etc., signals. Specifically, the CFAR input voltage is assumed to be of amplitude AN, where A is the amplitude of a linearly received signal. When using conventional in-phase (I) and quadrature (Q) channels, A = (I2 + Q2)12/. Emphasis is on CA-CFAR performance when the threshold is set for rejecting very spiky clutter which, for this study, is defined as having Weibull statistics with the parameter a = 5. Under these conditions, analyses indicate that for detecting a target in noise, a square-law (N=2)CA-CFAR input signal may provide 9.3 dB better detection sensitivity than does a linear (N=1) CFAR input. Also for targets in noise and a Weibull a = 5 clutter threshold setting, it appears that fourth order (N = 4) CFAR input may yield nearly 20 dB improvement over linear input. View full abstract»

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  • Feasibility analysis of GSM signal for passive radar

    Page(s): 425 - 430
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (506 KB) |  | HTML iconHTML  

    Passive radar makes use of an 'illuminator of opportunity' already present in the environment for other purposes (TV transmission, broadcast systems, etc) to detect targets as well as estimating target parameters. This radar has the merit of being a completely covert radar system, which does not advertise the presence of either the receivers or transmitting stations. One such existing radio transmission that may be utilize for this purpose is that of the GSM system. This paper is intended to access the feasibility and suitability of using the GSM downlink signals from the GSM base station as the 'transmissions of opportunity' in an experimental passive radar system. The analysis of the GSM signal as a radar waveform for the passive radar systems design and its associate signal processing scheme is investigated. Simulations and preliminary experimental results demonstrate that the detection of ground moving targets can be indeed be achieved, affirming that this system is indeed viable and for certain does offer a novel and unique kind of passive detection that is outside the scope of other current approaches. View full abstract»

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  • Adaptive space/frequency processing for distributed aperture radars

    Page(s): 160 - 164
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (369 KB) |  | HTML iconHTML  

    This paper deals a preliminary investigation into space-time-waveform adaptive processing for waveform diverse distributed apertures. The large baseline of such a distributed radar results in angular resolution that is orders of magnitude better than resolution of a monolithic system (single large radar) with the same power-aperture. This capability comes at the cost of grating lobes (multistatics with evenly spaced apertures) or high sidelobes (multistatics with randomly spaced apertures). This paper develops some preliminary solutions to these drawbacks associated with distributed apertures. In particular, the use of approximately logarithmic spacing with each aperture transmitting orthogonal waveforms provides excellent detection performance. View full abstract»

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  • A chirp signal parameter estimation algorithm and its application to SAR imaging of moving targets

    Page(s): 228 - 231
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (306 KB) |  | HTML iconHTML  

    This paper provides a novel method for estimating the parameters of linear frequency modulated (LMF) signals, or the so called chirp signals, based on a modification to the filter bank approach of the maximum likelihood estimation. This method reduces the computational complexity of the ML method. By using numerical simulations, the performance of the new approach is verified. Also we apply the algorithm to the raw data of an X-band airborne SAR with 3 m × 3 m resolution. Moving targets are successfully focused. View full abstract»

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  • Doubly adaptive bistatic clutter filtering

    Page(s): 171 - 178
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (558 KB) |  | HTML iconHTML  

    Bistatic aerospace radar systems offer certain operational advantages over their monostatic counterparts. However, bistatic radar must contend with spectrally severe ground clutter returns. Effective adaptive filtering is necessary to improve detection performance, but the non-stationary nature of bistatic clutter degrades performance. As a result, bistatic STAP techniques must incorporate modifications accommodating the unique aspects of the clutter returns. This paper introduces a new bistatic STAP technique based on a doubly adaptive process. The method offers substantial improvement over traditionally applied STAP methods. We also compare this method against some other recently proposed bistatic STAP approaches. View full abstract»

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  • Target detection in sea clutter using convolutional neural networks

    Page(s): 321 - 328
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (456 KB) |  | HTML iconHTML  

    A detector based on convolutional neural networks is proposed for radar detection of floating targets in highly complex and nonstationary cluttered environments. This detector is coherent and monocell, i.e. it works with the complex envelope of the echoes from the same range cell. It includes a pre-processing time-frequency block implemented by the Wigner-Ville distribution, which provides a constant false alarm rate (CFAR) behavior regarding the clutter power when normalization is utilized. Simple theoretical models for the clutter and targets were allowed to study the impact of the correlation and Doppler of both target and clutter on its performance. This detector has also been tested with real-life sea clutter with an improved performance compared to classic detectors. View full abstract»

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  • Non-linear STAP filters based on adaptive 2D-FIR filters

    Page(s): 51 - 58
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (503 KB) |  | HTML iconHTML  

    This paper presents a non-linear adaptive approach to the cancellation of clutter echoes in modern AEW radar systems equipped with digital beamforming. Two new STAP schemes are conceived by using different non-linear functions that are applied to the output of a bank of adaptive 2D FIR filters. The STAP schemes are shown to yield better detection performance than previously known schemes when operating in a non-stationary clutter background containing interfering targets. Since they require a limited increase of the computational load, compared to the single 2D-FIR filters, the proposed schemes can be regarded as practical solutions for robust and effective STAP of radar data. View full abstract»

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  • Target detection in heterogeneous airborne radar interference using 3D STAP

    Page(s): 252 - 257
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (453 KB) |  | HTML iconHTML  

    Heterogeneous interference is common-place in the airborne radar problem. Space-time adaptive processing fundamentals have struggled in the presence of such data. Originally, the solution involved simply increasing secondary data support, essentially "drowning" out heterogeneous interference effects. Research then progressed into identifying specific range cells containing heterogeneous interference and excising these cells from interference estimates. Yet, the target detection problem within heterogeneous interference remained. Therefore, research efforts abandoned statistical techniques and shifted towards deterministic methods with some success. Finally, the advent of a two-dimensional hybrid approach combined the diverse statistical and deterministic techniques into a single framework. This research effort continues in this vein by expanding the method into three-dimensions: azimuth, Doppler, and elevation. A 23 dB improvement over the three-dimensional joint domain localized method (3D-JDL) is shown for a specific heterogeneous interference case. View full abstract»

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  • The use of passive radar for mapping lightning channels in a thunderstorm

    Page(s): 28 - 33
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (504 KB) |  | HTML iconHTML  

    The state of Georgia has experienced a number of tornadoes that occur without warning and in several cases have caused fatalities. Researchers at the Severe Storms Research Center (SSRC) of the Georgia Tech Research Institute (GTRI), Georgia Institute of Technology are attempting to detect tornado formation within severe thunderstorms occurring in the vicinity of Atlanta, Georgia using non-radar sensors that may provide early tornado warning and provide cueing to existing national weather service (NWS) radars. The goal of these studies is to increase the warning time of tornado formation within the parent thunderstorm. GTRI researchers use real time S-band Doppler weather radar data from three national weather service (NWS) WSR-88D NEXRAD radars to complement the development of the non-radar tornado sensors. Three NWS Doppler radars provide severe weather surveillance coverage of the north Georgia area to determine if a thunderstorm contains the Doppler signature that indicates tornado formation. The radar data, displayed on a work station developed and optimized for tornado detection by the National Severe Storms Laboratory (NSSL), serves as ground truth data for the non-radar sensor development. GTRI can display cloud to ground (CG) lightning strikes, a capability provided by overlaying data from a national monitoring network onto the radar reflectivity map. GTRI also uses a local lightning direction finder (DF) system that supplies azimuth and range to the lightning strike. This paper discusses the early lightning channel research and the passive parasitic radar system being operated by the SSRC. View full abstract»

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  • High-efficiency L-band transmit/receive module for synthetic aperture radar

    Page(s): 238 - 243
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (478 KB) |  | HTML iconHTML  

    Space-based radar places significant demands on the spacecraft resources (mass, power, data rate) and is therefore very expensive to implement. These systems typically require active phased-array antennas with hundreds or thousands of transmit/receive (T/R) modules distributed on the array. High-efficiency is a vitally important figure of merit for the radar T/R module because it reduces the power consumption and therefore makes best possible use of the limited power available. High efficiency also improves the thermal design and reliability. In this paper, we describe the design and preliminary results of a novel L-band (1250 MHz) T/R module technology to achieve ultra-high efficiencies. We will show that a dramatic improvement in overall T/R module efficiency is possible using high-efficiency class-E/F amplifiers. The T/R module performance goals are to achieve an overall module efficiency greater than 70% with a minimum of 30-W output power at L-band frequencies. View full abstract»

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  • Three dimensional image reconstruction procedure over Barcer's code modulated ISAR signals

    Page(s): 210 - 215
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (434 KB) |  | HTML iconHTML  

    In the present paper a three-dimensional model of inverse synthetic aperture radar (ISAR) signal with Barcer's phase code modulation (BPCM) is created. A correlation image reconstruction procedure over three-dimensional ISAR data is developed. Numerical experiment over the simulated ISAR data with Barcer's phase code modulation is accomplished to demonstrate the validity of the proposed ISAR signal model and correlation image reconstruction procedure. View full abstract»

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  • Configuring a sparse aperture antenna for spaceborne MTI radar

    Page(s): 139 - 146
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (535 KB) |  | HTML iconHTML  

    Sparse arrays provide potential for improving the minimum detectable velocity (over 3 m/s improvement for sidelooking radar) of spaceborne moving target indication radar for a given physical aperture. This paper examines the benefits and some of the challenges resulting from employing sparse arrays: grating lobes introduce ambiguities that may create Doppler blind zones; area coverage rate may reduce due to a narrower antenna main beam for coherent transmission; and intrinsic clutter motion may reduce the usable fraction of the Doppler space. We consider the application of orthogonal transmit waveforms to increase area coverage rate, as well as frequency diversity and aperiodic subarray spacings to mitigate Doppler blind zones. View full abstract»

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  • Blind adaptive detection of distributed targets in compound-Gaussian clutter

    Page(s): 291 - 297
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (474 KB) |  | HTML iconHTML  

    This paper considers the problem of detecting distributed targets in the presence of compound-Gaussian noise with unknown statistics. At the design stage, in order to cope with the a priori uncertainty, we model clutter returns as Gaussian vectors with the same structure of the covariance matrix, but possibly different power levels. Hence, resorting to the method of sieves, we devise a fully blind detector, which ensures the constant false alarm rate (CFAR) property with respect to the disturbance power levels. Moreover the performance analysis confirms the capability of the novel receiver to operate in scenarios of practical interest for radar systems. Finally the comparison with the plain modified generalized likelihood ratio test (MGLRT), devised assuming Gaussian disturbance, and shows that even in the presence of Gaussian clutter, the newly proposed detector achieves satisfactory performance. View full abstract»

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  • Measurement extents and sampling intervals for multiple-bounce SAR image formation

    Page(s): 298 - 301
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (331 KB) |  | HTML iconHTML  

    Recent analysis has resulted in an innovative technique for forming spotlight synthetic aperture radar (SAR) images without the multiple-bounce (MB) ghosting artifacts that arise in traditional methods. This paper develops expressions for the measurement extents and sampling intervals in both frequency and aperture angle, which are required for a desired image resolution and extent in terms of the down-range coordinate, the cross-range coordinate, and the multiple-bounce or "delay" coordinate. The resulting analysis is validated via simulated frequency response data that includes the effects of multiple-bounce scattering. View full abstract»

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  • High frequency radar astronomy with HAARP

    Page(s): 154 - 159
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (394 KB) |  | HTML iconHTML  

    At high frequency, radio waves will interact with space plasmas and surfaces of local astronomical objects, producing an echo that can provide new diagnostic data. The availability at high power radars operating at high frequencies opens a window for the remote investigation of our surrounding space environment. We discuss and illustrate this technique with some specific examples. View full abstract»

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  • Maximum likelihood angle extractor in the presence of sea-surface multipath

    Page(s): 337 - 344
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (491 KB) |  | HTML iconHTML  

    In the presence of sea-surface multipath, the standard monopulse ratio technique to extract elevation angle of target produces large bias. In this paper we propose a maximum likelihood (ML) angle extraction technique for low elevation targets above the sea surface, of known average signal strength having a Rayleigh fluctuation. The procedure is then modified for targets having unknown average signal strength. The resulting modified angle extractor has only a small performance degradation compared with the known average signal strength case, but it performs much better than the monopulse ratio based estimator. This angle extractor reduces the root mean square error (RMSE) by more than 50% in the signal processing stage when used for low flying target tracking scenarios. Further improvement is achieved by using the predicted average target signal power in dynamic scenarios where a significant reduction in the tracker RMSE performance can be achieved, as shown in the simulations presented. View full abstract»

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