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Radar, Sonar and Navigation, IEE Proceedings -

Issue 5 • Date 10 Oct. 2004

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Displaying Results 1 - 9 of 9
  • Investigation of the variability of Doppler spectra with radar frequency and grazing angle

    Publication Year: 2004 , Page(s): 291 - 298
    Cited by:  Papers (2)
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (482 KB)  

    The effect of varying grazing angle on the Doppler spectra of radar backscatter from wind waves has been investigated in a laboratory wave tank. Five different radar frequencies were used and six different wind conditions, for a range of grazing angles between 3° and 24°. The results show linear relationships between the velocity of the dominant scattering components and the grazing angle. This effect is hard to reconcile with a scattering mechanism based on Bragg resonance. Data from a cliff-top radar were also examined. View full abstract»

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  • Capon-LS for model order selection of multicomponent interferometric SAR signals

    Publication Year: 2004 , Page(s): 299 - 305
    Cited by:  Papers (2)
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (683 KB)  

    The authors address the problem of estimating the number of components in a multibaseline interferometric synthetic aperture radar (InSAR) signal, corrupted by complex correlated multiplicative noise, in the presence of the layover phenomenon. The appearance of multiplicative noise, termed 'speckle', makes this problem very atypical. In fact, all the approaches proposed in literature have been applied to constant amplitude sinusoidal signals. In particular, the information theoretic criteria (ITC) have been conceived for estimating the number of signal components embedded in additive white noise. In this case, the problem is equivalent to the estimation of the multiplicity of the smallest eigenvalues of the data covariance matrix. In the presence of multiplicative noise, the signal eigenvalues spectrum changes. Consequently, the classic ITC methods operate under model mismatch. In a previous work, the authors investigated their robustness to speckle. An ad hoc algorithm for model order selection, based on Capon and least squares methods is developed. Its performance is analysed via Monte Carlo simulation and compared with those of classic ITC. View full abstract»

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  • Low probability of intercept radar strategies

    Publication Year: 2004 , Page(s): 249 - 260
    Cited by:  Papers (11)
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (309 KB)  

    To reduce probability of intercept, in most cases, the form and magnitude of the radar transmissions are designed to spread energy over as wide a range of dimensions as possible. Equally, in response to this, designs for electronic surveillance measures (ESM) systems have been postulated that increase receiver sensitivity. Their purpose is to increase detection range beyond that of the radar (or to an adequate range if they are to be forward deployed). The authors examine the evolving nature of the relationship between advanced 'low probability of intercept' (LPI) radar designs and future trends in ESM receiving capability. This relationship is far from straightforward, being both probabilistic and dependent on environmental and operational factors. Indeed this is complicated still further by the issue of affordability. The authors compute the performance of ESM and radar systems for a number of cases, including not just simple interception, but also the extraction of information from intercepted signals. In this way the key factors influencing the detectability of LPI radar systems are determined. It is demonstrated that it is never possible to be completely certain that a radar system has not been detected and that the most appropriate way to implement an LPI radar design is always closely related to the tactical environment in which the radar system will be used. Indeed this often overrides the technical aspects of system performance. View full abstract»

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  • Migration based SAR imaging for ground penetrating radar systems

    Publication Year: 2004 , Page(s): 317 - 325
    Cited by:  Papers (9)  |  Patents (1)
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (1336 KB)  

    The authors consider migration based synthetic aperture radar (SAR) imaging of surface or shallowly buried objects using both down-looking and forward-looking ground penetrating radar (GPR). The well known migration approaches devised to image the interior of the Earth are based on wave equations and have been widely and successfully used in seismic signal processing for oil exploration for decades. They have the potential to image underground objects buried in complicated propagation media. Compared to ray-tracing based SAR imaging methods, migration based SAR imaging approaches are more suited to imaging underground objects owing to their simple and direct treatment of oblique incidence at the air-ground interface and propagation velocity variation in the soil. The authors apply the phase-shift migration approach to both constant-offset and common-shot experimental data collected by PSI GPR systems. They address the spatial aliasing problems related to the application of migration to the GPR data and the spatial zero-padding approach to circumvent the problem successfully. View full abstract»

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  • Invariant-based probabilistic target tracking and identification with GMTI/HRR measurements

    Publication Year: 2004 , Page(s): 280 - 290
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (757 KB)  

    An invariant-based algorithm is presented for ground moving-target tracking and identification using ground moving-target indicator and high-resolution range measurements. The algorithm effectively exploits coupled information between target kinematics and identification spaces by introducing the concept of local and global motion. A geometrical invariant constraint based on the target rigidity principle is built into target kinematics and measurement models, which facilitate joint information exploitation. An interacting multiple template algorithm is developed to tightly work with a traditional tracker for joint tracking and identification. Besides providing target kinematics behaviour and identity information, the algorithm is capable of reconstructing the prominent physical structure of a moving target. View full abstract»

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  • Automatic seabed classification by the analysis of sidescan sonar and bathymetric imagery

    Publication Year: 2004 , Page(s): 327 - 336
    Cited by:  Papers (2)
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (1546 KB)  

    The authors present a technique for making use of both sidescan amplitude and bathymetric data provided from sidescan bathymetric sonars for the classification of underwater seabeds. Sidescan amplitude is corrected for physical factors and used to plot 'processed' sidescan images. Both amplitude and textural features are derived from these images. Textural features are obtained using 2-D discrete wavelet transforms. Bathymetric images are used to derive features indicating seafloor variability. These features are combined together and the most relevant ones are selected by feature selection algorithms. If grab samples are available, the areas around them are used as training data in a supervised approach. The backpropagation elimination algorithm is used on the training dataset to select relevant features. If training data are not available, an unsupervised approach can be used. The dimensions of the whole dataset are reduced using principal component analysis in this case, and the principal components are used as features. In both cases, clustering techniques are used to cluster the data into sediment classes. The classified points are then plotted against their GIS position in the survey. Classification results correlate with grab sample types from the areas considered (in the supervised case) and with expert observation of sidescan images, where training data is not available. View full abstract»

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  • Super-fast scanning technique for phased array weather radar applications

    Publication Year: 2004 , Page(s): 271 - 279
    Cited by:  Papers (4)
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (1348 KB)  

    The authors present a super-fast scanning (SFS) technique for phased array weather radar applications. The fast scanning feature of the SFS technique is described and its drawbacks identified. Techniques which combat these drawbacks are also presented. A concept design phased array radar system (CDPAR) is used as a benchmark to compare the performance of a conventional scanning phased array radar system with the SFS technique. It is shown that the SFS technique, in association with suitable waveform processing, can realise four times the scanning speed and achieve similar accuracy compared to the conventional phased array benchmark. View full abstract»

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  • Target fluctuation models and their application to radar performance prediction

    Publication Year: 2004 , Page(s): 261 - 269
    Cited by:  Papers (10)
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (336 KB)  

    The authors address the design, analysis, and experimental validation of statistical models for the description of targets fluctuations. First some classical distributions commonly employed for the statistical characterisation of the target amplitude returns are reviewed. Then, the authors focus on the shadowed Rice and the two-state Rayleigh-chi target models, discussing their physical justification and relevant analytical properties. The capabilities of the considered models to fit real target data collected by the McMaster IPIX radar in 1993 are also studied. Finally, the performance of the optimum detector (in the Neyman-Pearson sense) for targets with uniformly distributed phases in the presence of shadowed Rice and two-state Rayleigh-chi fluctuations is studied and analytical expressions are provided for the detection probability. View full abstract»

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  • Detection of land-mines using ultra-wideband radar data and time-frequency signal analysis

    Publication Year: 2004 , Page(s): 307 - 316
    Cited by:  Papers (1)  |  Patents (8)
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (2012 KB)  

    The authors present a study of the backscattered signatures from various types of land-mines placed either on the Earth's surface or buried underground, and their time-frequency (t-ν) distributions. A BoomSAR designed by the Army Research Laboratory (ARL) transmits ultra-wideband (UWB) signals to a test area to be inspected. The backscattered signals are used to form synthetic aperture radar (SAR) imagery and also the corresponding time-frequency distributions. The t-ν plots are generated of the distributions of several mines and 'confusers' (i.e. undesirable debris that are similar to mines in terms of amplitude and shape). For both metal and plastic mines, SAR images are generated and the t-ν distributions are obtained using the backscattered signals generated by an electromagnetic (EM) numerical model and are compared against the measured data. Time-frequency characteristics of mines and confusers that may be useful for demining purposes are investigated. Although measurements and EM predictions show good agreement in most cases, the main purpose of the work is to obtain the characteristics of the t-ν distributions of the actual (dielectric and conducting) mines used, as well as those of the 'confusers' so that they can be distinguished from the true mines. This has been achieved in all cases shown, and many distinctive features of each have been identified. These could later be used for the development of automated algorithms for in-situ mine detection and could be combined with alternative approaches that have also shown promise for classification purposes, as planned for future research. View full abstract»

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Aims & Scope

IEE Proceedings Radar, Sonar and Navigation covers the theory and practice of systems involving the processing of signals for radar, radio location, radio navigation and surveillance purposes.

Full Aims & Scope