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Radar, Sonar and Navigation, IEE Proceedings -

Issue 1 • Date Feb 1996

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Displaying Results 1 - 8 of 8
  • MVDR vectorial lattice applied to space-time processing for AEW radar with large instantaneous bandwidth

    Page(s): 41 - 46
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (628 KB)  

    The problem of space-time processing is described for a generic airborne early warning radar with large instantaneous bandwidth. The mathematical models of target, clutter, directional EM interference, and receiver noise are introduced together with the scheme of the optimum detection processor. The performance of the processor is determined for a number of operational situations as a function of the radar and processor parameters; performance curves provide guidelines for the selection of the radar parameters. When the interference covariance matrix is not known a priori, the MVDR (minimum variance distortionless response) algorithm is applied to determine a numerically robust and efficient adaptive processor. This leads to a so-called vectorial lattice computational flow graph which can be mapped on to a fine grain parallel systolic computing architecture. The performance of the adaptive vectorial lattice scheme is compared to that of the optimum scheme to evaluate the adaptivity loss. A perspective to further theoretical and practical investigations concludes the paper View full abstract»

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  • Automated propagation advice for OTHR ship detection

    Page(s): 53 - 63
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (1652 KB)  

    The ability of an over-the-horizon radar to detect ships is critically dependent on the choice of operating frequency. The author describes an automated surface mode propagation advice system which has been installed into the Jindalee Over-the-Horizon Radar Facility at Alice Springs (23.5S, 133.7E). The advice is chiefly derived from backscatter measurements performed by the Jindalee Frequency Management System's Doppler `miniradar' and includes the optimum operating frequency and a predicted performance indicator for each specific operational radar mission. Global displays of predicted performance, covering the entire surveillance region, are also provided to allow the system to nominate areas where ship detection would be viable with the operational radar. Details on the function, input and output of component modules of the system are included, as well as the basic input data requirements. A sample of the output and diagnostic displays are presented. A few limitations to the system performance have been found. These limitations are described along with the future effort that is required to overcome them View full abstract»

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  • Estimation of the directions of arrival of spatially dispersed signals in array processing

    Page(s): 1 - 9
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (868 KB)  

    The problem of estimating the DOA of spatially distributed signals is examined. A mathematical model is first established by making some reasonable assumptions. The correlation matrix of a distributed signal is then derived. The important properties of the correlation matrix are studied, revealing that even if the matrix is of full rank (being equal to the number of sensors), which renders conventional high resolution array processing methods inapplicable, the dimensionality of the signal subspace can be approximated to a number usually much smaller than the number of sensors. From the observation, the quasi-signal and noise subspaces are identified, and, utilising the orthogonality of the signal and noise subspaces, an algorithm (DISPARE) has been developed. Analytic studies and numerical evaluations are carried out to examine the performance of the algorithm under various environments and show that it is indeed effective View full abstract»

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  • Advances in aircraft-height estimation using distance-measuring equipment

    Page(s): 47 - 52
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (548 KB)  

    The authors address the subject of aircraft geometric-height estimation, based on measurements from three distance-measuring equipment (DME) stations. A new improved height computation algorithm is presented, which is computationally efficient and mathematically tractable. The simple form of the new algorithm leads to easy derivation of analytic expressions for both the standard deviation and inherent systematic errors. Evaluation results are presented for representative conditions. The appropriate form of filtering algorithm is proposed for producing bias-free and more accurate height estimates View full abstract»

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  • Adaptive probabilistic data-association algorithm for tracking in cluttered environment

    Page(s): 17 - 22
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (528 KB)  

    A probabilistic data-association filter which uses adaptive update times, for tracking a target in a cluttered environment and in an environment where the probability of detection (Pd) is less than the unity, is presented and compared with the probabilistic data-association filter which uses a constant update time. The tracking performance of the algorithm is assessed by Monte Carlo simulation on different target trajectories. A comparison is made using the percentage of tracks lost, the mean-square errors, the mean update times and mean number of updates View full abstract»

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  • Enhanced forward/backward spatial filtering method for DOA estimation of narrowband coherent sources

    Page(s): 10 - 16
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (600 KB)  

    The forward-only filtering approach first suggested by A. Moghaddamjoo (1991) to estimate the direction of arrival (DOA) of narrowband coherent sources is further investigated. The authors propose and analyse an improved method based on the application of a suggested forward/backward spatial filtering scheme of an array vector. They show that this method significantly improves the signal resolution and they prove that their method requires fewer sensor elements than the other filtering approaches. The effectiveness of the proposed algorithm is also proved in the general case of a mixed source scene consisting of fully correlated (coherent) and partially correlated signals. Monte-Carlo simulation experimental results that confirm the analysis are presented as well View full abstract»

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  • Optimum edge detection in SAR

    Page(s): 31 - 40
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (956 KB)  

    Different window configurations and measures for detecting edges between regions of different mean in synthetic-aperture radar (SAR) images are compared. Two criteria for optimisation are considered: (i) maximising the total probability of detecting an edge within a window; and (ii) maximising the accuracy with which the edge position can be determined. Clearly, an ideal edge detector would combine both properties. Maximum-likelihood solutions to the two criteria are discussed and it is shown how they determine the choice of both window configuration and the measure adopted. The performance degradation encountered when the tests are applied to the scenario for which they are not optimised is compared and the test which best meets both original criteria is identified. Combination of the good features of each to yield the best overall performance in a two-stage edge-detection scheme is discussed View full abstract»

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  • Optimised design of Jaumann radar absorbing materials using a genetic algorithm

    Page(s): 23 - 30
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (744 KB)  

    The design of wideband, multilayer radar absorbing materials involves the solution of an N-dimensional optimisation problem. Genetic algorithms appear to offer significant advantages over conventional optimisation techniques for this type of problem owing to their robustness and independence of performance function derivatives. To illustrate their use, the paper considers two problems: first the optimum design of wideband, multilayer, passive Jaumann radar absorbers with or without an outer high-permittivity skin; and secondly, an examination of the potential of such absorbers when configured as active, i.e. frequency agile, dynamic structures 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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