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Radar and Signal Processing, IEE Proceedings F

Issue 1 • Date Feb 1992

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Displaying Results 1 - 12 of 12
  • Some aspects of array signal processing

    Page(s): 1 - 26
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (2504 KB)  

    The authors present an overview of some important aspects of array signal processing in the context of narrowband applications. Inverse methods are reviewed. Two case studies are presented. Different kinds of nonuniformly spaced linear arrays are also reviewed, with particular attention given to minimum redundancy and nonredundant arrays. The tradeoffs; namely, array span and sampling gain that decide the choice of one nonuniform configuration over another, are discussed. To aid in this study, the well known Cramer-Rao lower bound (CRLB) and the newly developed Weiss-Weinstein lower bound (WWLB) are computed for the simple and yet informative case of a single source under different conditions. A novel method for the adaptive (online) control of the measurement space (and therefore the amount of information available for parameter estimation) is described. Also included are real-time processing considerations, and a review of calibration array techniques View full abstract»

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  • Efficient computation of the split-radix FFT

    Page(s): 56 - 60
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (332 KB)  

    The authors look at the efficient computation of the one-butterfly inplace complex split-radix fast Fourier transform algorithm. The proposed approach is based on the conventional three-loop indexing structure, in which redundancies associated with the indexing scheme have been removed at the expense of memory. As a result an increase in speed of up to 10% is achieved depending on the FFT sequence length View full abstract»

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  • Improved algorithm for the deinterleaving of radar pulses

    Page(s): 98 - 104
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (576 KB)  

    The authors present an improved method for the deinterleaving of radar signals, based on a time of arrival analysis and the use of the sequential difference histogram (SDIF) for determining the pulse repetition interval (PRI). The optimal detection threshold in the SDIF histogram is derived, which greatly contributes to the efficiency of the algorithm. The algorithm is applied to classic, frequency-agile and staggered PRI radar signals. It is shown that the new method is very successful in high-pulse-density radar environments and for complex signal types. Special attention is given to an application of this method to the multiple-parameter deinterleaving algorithm View full abstract»

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  • Detection and imaging of moving objects with synthetic aperture radar. 1. Optimal detection and parameter estimation theory

    Page(s): 79 - 88
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (936 KB)  

    The author provides optimal schemes, according to the maximum likelihood criterion, for the detection of moving objects observed by airborne radars, and for the synthesis of a long aperture with respect to the moving objects, necessary to produce high-resolution images. The theoretical limits of detectability and of the accuracies achievable in the estimation of the motion parameters necessary for the synthesis of the long aperture are provided. Some simple suboptimal schemes, with limited performance losses, are then proposed View full abstract»

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  • Effect of system noise on the performance of a noncoherent monopulse processor [radar]

    Page(s): 61 - 66
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (360 KB)  

    An amplitude based angle (ABA) processor is a noncoherent monopulse processor operating at the output of a square-law detector. The performance of an ABA processor is insensitive to phase imbalances at the IF stage of a monopulse receiver and its glint performance is superior to that of the exact processor. The effect of system noise on the accuracy of the angle indicated by the ABA processor is analysed. Explicit expressions for the probability-density functions of the indicated angle are derived for steady and fluctuating (Swerling type-1) targets. The performance of the ABA processor is then compared with that of the exact processor using bias andstandard deviation in the indicated angle as the criteria. Computer simulations are presented to confirm the theoretical predictions View full abstract»

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  • Parallel adaptive rooting algorithm for general frequency estimation and direction finding

    Page(s): 43 - 48
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (448 KB)  

    An adaptive rooting algorithm, is proposed for tracking the nonstationary roots of null spectra for data from sensor arrays, or time series. Without the assumption of uniformity for linear arrays, this adaptive-rooting algorithm associated with the zero-extraction technique is further extended to construct a parallel-effective-rooting processor. The adaptive algorithm tracks all the principal roots and reduces the computational complexity from order N3 to order N2. Simulation show better resolution performance of the suggested algorithm than that of the usual of spectral-based high-resolution techniques such as minimum-norm or MUSIC, for both uniform and nonuniform cases. Simulations also reveal that its convergence speed competes with those of recent fast adaptive eigen-structure algorithms for tracking the nonstationary parameters View full abstract»

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  • Nonuniform sampling and study of transient systems response

    Page(s): 49 - 55
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (492 KB)  

    Nonuniform sampling where sampling intervals are chosen by various criteria of the noisy signal is investigated. In this context, the minimum-variance polynomial approximation is used to reconstruct the signal values at uniform spacings. The statistical characterisation of error in the reconstructed signal values, and use of that property in an approximate maximum likelihood estimator, lead to very accurate results related to the study of transient system-response in noise. In the special case of uniform sampling, it is explained why the performance of the proposed method, which first preprocesses data by polynomial approximation, is superior to the performances of the existing methods based on singular value decomposition. Simulation results are presented to substantiate the theory View full abstract»

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  • Electromagnetic geophysical tomography

    Page(s): 27 - 35
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (824 KB)  

    An electromagnetic tomographic method for subsurface imaging is described. It reconstructs the electrical conductivity and dielectric permittivity profiles of the medium under investigation from phase-shift measurements of the received signals. Ray-optic approximations are made so that the problem reduces to solving two linear systems of equations. This is accomplished by a stable algebraic reconstruction algorithm. The method is tested with the cross-hole geometry using synthetic data. This geometry leads to an incomplete-data problem because the region of interest is investigated only from its lateral boundaries. Computer simulations show that the features of the host medium can be reliably reconstructed even in the presence of noisy data. The tomographic algorithm described has the very desirable characteristic of being self-correcting View full abstract»

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  • Alternative signal processor arithmetic for modified implementation of a normalised adaptive channel equaliser

    Page(s): 36 - 42
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (536 KB)  

    A signal processor arithmetic based on a CORDIC and an array-multiplier/accumulator unit is proposed and an efficient implementation of an adaptive equaliser is given as an example. The concept combines the normalised lattice gradient and the well known LMS algorithm. The advantage of this approach is that the gradient lattice algorithm is less complex than the normalised least-squares lattice algorithm and only slightly slower, yet is still much faster than the gradient transversal LMS algorithm. It is shown that the modified CORDIC algorithm with the proposed arithmetic can reduce the computational complexity. To corroborate this point the computational efficiency and the amount of hardware needed for the proposed implementation are investigated View full abstract»

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  • Analogue-to-digital convertor effects on airborne radar performance

    Page(s): 73 - 78
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (520 KB)  

    Detection of low cross-section targets in strong and varying clutter requires linear radar signal processing with a wide dynamic range. Analogue-to-digital (A/D) convertor characteristics are critical to achieving this dynamic range. A/D convertors generate internal noise and spurious harmonics due to nonlinearities, in addition to the theoretical quantisation noise. To evaluate A/D convertor effects on airborne radar performance, a model has been developed, based on the measured harmonic levels of a 14-bit A/D convertor, and is included in an airborne radar simulation. The authors describe the details of the model and the radar simulation, and compare the performance of the high pulse repetition frequency (PRF) radar system using an ideal A/D convertor with that of the A/D convertor model View full abstract»

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  • Detection and imaging of moving objects with synthetic aperture radar. 2. Joint time-frequency analysis by Wigner-Ville distribution

    Page(s): 89 - 97
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (788 KB)  

    For pt.1 see ibid., vol.139, no.1, p.79-88 (1992). The authors show how time-frequency representation by Wigner-Ville distribution of the echoes received by a synthetic aperture radar provides a useful tool for detection of moving objects and the estimation of the instantaneous phase shift induced by relative radar-object motion. The phase history is then used to compensate the received signal and to form a synthetic aperture with respect to the moving object, necessary to produce a high resolution image View full abstract»

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  • Analytic comparison of four robust algorithms for post-detection integration [radar detection]

    Page(s): 67 - 72
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (392 KB)  

    Four radar integration algorithms are compared with the basic moving window integrator. The algorithms are robust in the sense of immunity against strong interfering spikes. Very strong spikes can appear if several radars operate in close proximity. The algorithms have been previously suggested for integration or are borrowed from CFAR thresholding methods. The author provides an analytic performance analysis for a simple signal (Swerling II), noise and interference model. The comparison of the four algorithms, in the situation covered by this model, may be indicative of their relative performances in more realistic models, for which it is more difficult to obtain closed-form results View full abstract»

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Aims & Scope

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

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