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Radar, Sonar and Navigation, IEE Proceedings -

Issue 1 • Date Feb 2002

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Displaying Results 1 - 8 of 8
  • Radar angle-tracking system for multiple moving targets

    Page(s): 23 - 28
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (537 KB)  

    A radar angle-tracking system for tracking multiple moving targets is proposed which generates the instantaneous optimal estimates of angles regardless of angle dynamics, reducing the computational burden and eliminating the effect of the time-varying parameters on the angle estimation. However, it is shown that the angle data generated by the angle-tracking system are sufficient to construct the optimal estimator of the time-varying angles of multiple targets in any dynamic motions View full abstract»

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  • High resolution 3-D imaging via multi-pass SAR

    Page(s): 45 - 50
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (767 KB)  

    Spaceborne/airborne synthetic aperture radar (SAR) systems provide high resolution two-dimensional terrain imagery. The paper proposes a technique for combining multiple SAR images, acquired on flight paths slightly separated in the elevation direction, to generate high resolution three-dimensional imagery. The technique could be viewed as an extension to interferometric SAR (InSAR) in that it generates topographic imagery with an additional dimension of resolution. The 3-D multi-pass SAR imaging system is typically characterised by a relatively short ambiguity length in the elevation direction. To minimise the associated ambiguities we exploit the relative phase information within the set of images to track the terrain landscape. The SAR images are then coherently combined, via a nonuniform DFT, over a narrow (in elevation) volume centred on the 'dominant' terrain ground plane. The paper includes a detailed description of the technique, background theory, including achievable resolution, and the results of an experimental study View full abstract»

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  • Air target detection via bistatic radar based on LEOs communication signals

    Page(s): 33 - 38
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (699 KB)  

    The paper discusses the bistatic radar parameters for the case when the transmitter is a satellite emitting communication signals. The model utilises signals from an Iridium-like low Earth orbiting satellite system. The maximum detection range, when thermal noise-limited, is discussed at the theoretical level and these results are compared with experimentation. Satellite-radar signal levels and the power of ground reflections are evaluated View full abstract»

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  • Application of the generalised radiance function for prediction of the mean RCS of bent chaotic ducts with apertures not normal to the duct axis

    Page(s): 9 - 15
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (637 KB)  

    A method is proposed to approximate the mean radar cross-section (RCS) of a chaotic electrically large bent duct with an aperture not necessarily normal to the duct axis. This is based on a ray mapping of the generalised radiance function (GRF) associated with a random field. The field within the duct is assumed to be represented by a scalar function and a homogenous Schell model is assumed to describe the backscattered transverse field at some cross-section within the duct. The GRF associated with this field may then be mapped to a general aperture where the mean RCS can be determined. An analytic example is provided where a chaotic bent duct is terminated by a prism-shaped precursor structure View full abstract»

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  • New approach to target identification by use of a robust algorithm for optimal matching of wideband radar signal to target

    Page(s): 16 - 22
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (587 KB)  

    Using an array of coupled oscillators, a novel broadband radar signalling scheme is introduced. It is shown that the collective output of the oscillator array is a flexible signal that can be matched to a target at a specific aspect. Also, a new robust algorithm based on eigenvectors of the correlation matrix is introduced, by which the generated signal can be matched to the target over a limited range of aspects. This capability is important, because radars are unable to estimate the aspect of a real target precisely. In this new approach to radar target identification, after estimation of the approximate aspect of an unknown target, a variety of waveforms matched to different potential targets are synthesised and transmitted to the target in turn. The maximum peak power of the backscattered signals will then specify the identity of the target. Computer simulations have shown that this technique is robust to both additive noise and aspect angle uncertainty View full abstract»

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  • Target track extraction procedure for OLPI antenna data on the basis of Hough transforms

    Page(s): 29 - 32
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (566 KB)  

    Hough (1962) transformations were developed in order to recognise automatically geometrically describable patterns (especially straight lines) in pictures. This happens by transforming the picture points onto pattern parameters, discretising the parameter space into cells, and registering the number of votes in individual cells. The application of Hough transformations to radar data processing (track extraction) is impeded by the fact that target tracks possess a time-dependent evolution (target velocity). When processing real antenna data, the pure existence of a target track cannot be assumed, and the point of time of its appearance and endurance cannot be predicted. A procedure of recursive radar data processing on the basis of Hough transformations is described. The known partitioned Hough parameter space is, therefore, supplemented by another discretised dimension: the time. Instead of transforming the radar plots themselves, segments of straight lines constructed from two radar plots (eventually belonging to a target track) are transformed onto the extended Hough parameter space. The procedure is able to recognise straight line target tracks. It is applied to real antenna data of the omnidirectional low probability of intercept (OLPI) experimental radar system View full abstract»

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  • Stochastic Cramer-Rao bound for direction estimation in unknown noise fields

    Page(s): 2 - 8
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (615 KB)  

    The stochastic Cramer-Rao bound (CRB) plays an important role in array processing because several advanced high-resolution direction-of-arrival (DOA) estimation methods are known to achieve this bound asymptotically. In the paper, the stochastic CRB on the DOA estimation accuracy is studied in the general case of an arbitrary unknown noise field parameterised by a vector of unknowns. Explicit closed-form expressions for the CRB are derived and its properties are examined theoretically and by practically relevant numerical examples View full abstract»

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  • Suppression of sea clutter with orthogonal weighting for target detection in shipborne HFSWR

    Page(s): 39 - 44
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (565 KB)  

    It is difficult to detect a target submerged in the spread spectrum of the first-order sea clutter in shipborne HFSWR (high frequency surface wave radar). Based on the space-time distribution of the first-order sea clutter, a technique for the detection of a ship in the spread-clutter spectrum is presented, which can completely suppress interference coming from a known incident direction. The influence of orthogonal weighting on the mainbeam directed at the target is slight when interference is outside the mainbeam. Angle measurement can then be accomplished as for an onshore HFSWR. However, suppression of interference coming from within the main target beam would result in this mainbeam splitting into two beams. It is shown that amplitude comparison of the two split beams can be used to determine the azimuth of the target. Processing the results from the experimental data demonstrate reliable ship detection and estimation on the Yellow Sea of China 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.

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