By Topic

Radar and Signal Processing, IEE Proceedings F

Issue 5 • Date Oct 1989

Filter Results

Displaying Results 1 - 5 of 5
  • CFAR detection for multiple target situations

    Page(s): 193 - 209
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (832 KB)  

    Three detectors are proposed and studied in the presence of interfering targets in the reference cells. In the weighted cell-averaged constant false-alarm rate (WCA-CFAR) detector the means generated by the leading and the lagging range cells are weighted in accordance with the level of the interference. Optimum weights that maintain CFAR are obtained while the probability of detection is maximised. The censored mean level detector (CMLD) is considered next, this requires exact knowledge of the number of interfering targets. The detection performance of the CMLD is studied for Swerling IV targets and compared to that with Swerling II targets. Then, the generalised censored mean-level detector (GCMLD) is proposed. The GCMLD does not require a priori knowledge of the number of interfering targets and achieves robust performance. The number of interfering targets is determined and their corresponding samples are then censored. Exact expressions for the probability of censoring the interfering targets and the overall probability of detection are derived. A comparison of the performance of the GCMLD with that of a recently proposed CFAR detector is also presented to demonstrate the robustness of the GCMLD. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Fractal modelling in image texture analysis

    Page(s): 227 - 235
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (772 KB)  

    A fractal analysis procedure for the processing of visual textures is investigated. The method uses second-order spatial statistics to calculate the rate of change of a local estimate of the fractal dimension over different scales and orientations. Possible deficiencies caused by aliasing within a known technique are examined, together with the performance of a modified version which incorporates appropriate filtering. Results with the modified technique show that it is able to test the validity of the fractal model for real visual textures. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Comparison of techniques for measuring cloud texture in remotely sensed satellite meteorological image data

    Page(s): 236 - 248
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (1316 KB)  

    The investigation has attempted to discover appropriate texture descriptors and to reveal more clearly the importance of texture analysis techniques for multispectral cloud classification. The textural features considered in the study include both spatial and frequency features. The spatial features were mainly those based on spatial grey-level difference statistics and circular Moran autocorrelation measures. The frequency features were those based on summed energies of polar coordinate Fourier power spectra and entropy-based measures of the spatial distribution of frequency entries in the polar spectra. Some other textural features, such as the Roberts gradient measure, were also investigated. The work was performed with TIROS-N AVHRR image data acquired in the late spring of 1979 over areas near the British Isles. The results of the evaluation and corresponding conclusions show which individual, and group of textural features, appear the most appropriate for aiding multispectral cloud classification. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Elliptical boundary arrays for coherent and incoherent imaging

    Page(s): 210 - 220
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (656 KB)  

    In the imaging of far-field source distributions by a planar array of antenna elements, the quality of the image is determined by the beam pattern of the array. The physical size of the aperture ultimately determines its resolution capability, and the excitation or weighting imparted to the aperture controls the sidelobe characteristics. For a given number and spacing of antenna elements, the largest physical apertures are formed if the elements are distributed only around the boundaries of the apertures. This, however, results in beam patterns with rather high sidelobes. Thus it is of clear practical advantage to have available a technique for effectively filling in the interior of such a boundary aperture through appropriate signal processing applied to the boundary element signals. The paper builds on early results concerning such a technique, which made use of incoherent (receive-only) imaging systems. It is shown that for both incoherent imaging, the latter implemented using a transmit/receive scheme, it is possible to obtain such a filling-in or interpolation effect when imaging with an array composed of an elliptical (or circular) arrangement of array elements. Explicit synthesis theorems which give a specific constructive approach to implementing this effective interpolation to any desired degree of accuracy are given, and this approach is illustrated by giving the results of simulations, both with and without element location errors. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Fast automatic registration for satellite imagery by using heuristic planning

    Page(s): 221 - 225
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (404 KB)  

    A fast algorithm for the automatic registration of remotely sensed images obtained from satellites has been developed. The automatic section is based on an orbital model and a library of ground control points. The real problem of an excessive searching requirement for similarity measure is tackled by using heuristic planning. This method reduces the search space to a less detailed compact size, which is later used as a plan for finding the exact coordinates and which confines the search window to a small region. The improved procedure has achieved subpixel accuracy with a substantially reduced registration time. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.

Aims & Scope

The latest version of this title is Radar, Sonar & Navigation, IET.

Full Aims & Scope