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Radar, Sonar and Navigation, IEE Proceedings -

Issue 6 • Date 9 Dec. 2005

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Displaying Results 1 - 8 of 8
  • Cross-correlation of long binary signals with longer mismatched filters

    Page(s): 377 - 382
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (495 KB)  

    Mismatched processing of long binary signals is revisited. The filter is optimised for minimum integrated or peak sidelobes. The importance of choosing a signal with favourable autocorrelation is demonstrated using a few examples. View full abstract»

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  • Adaptive array beamforming with robust capabilities under random sensor position errors

    Page(s): 383 - 390
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (645 KB)  

    The problem of adaptive array beamforming with multiple-beam constraints in the presence of steering error caused by random sensor position errors is considered. First the statistical relationship between the random sensor position errors and the induced random phase perturbation is derived. Based on the result, a cost function consisting of terms which utilise a posteriori information owing to the received array data and a priori information owing to the probabilistic distribution of the resulting phase perturbation, respectively, is constructed. Then, an appropriate estimate of the actual phase angle vector associated with each of the desired signals can be obtained by performing a nonlinear optimisation problem. An implementation algorithm is further presented to solve iteratively the problem. Theoretical analysis regarding the convergence property of the iterative procedure is also investigated. Finally, several computer simulation examples are provided for demonstrating the effectiveness of the proposed technique View full abstract»

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  • Three-dimensional bistatic synthetic aperture radar imaging system: spatial resolution analysis

    Page(s): 391 - 394
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (149 KB)  

    A mathematical framework for analysing the spatial resolving capability of a general three-dimensional bistatic synthetic aperture radar imaging system, in which the transmitter, receiver and imaged object (or region of interest) may be non-coplanar and in which the transmitter and/or receiver may be moving, is presented. With Earth observation applications in mind, this framework is used to characterise quantitatively the two-dimensional ground-plane resolving capability of the three-dimensional imaging system. The theoretical results are confirmed via simulations. View full abstract»

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  • Use of dynamic radar signature for multistatic passive localisation of helicopter

    Page(s): 395 - 403
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (506 KB)  

    The passive radar concept is very attractive with regard to the covertness and detectability of a low-altitude flying target by use of low-frequency opportunistic signals. Detection performances are described in a large number of published papers showing the feasibility of passive detection. Accurate localisation of a target is more problematic, because it requires appropriate opportunistic signals for range compression as well as a large receiving antenna for accurate angular measurement. The introduced concept considers the exploitation of the dynamic signatures returned by helicopters to facilitate their localisation. A multistatic configuration with at least three receivers is considered. Flash echoes observed on each of the bistatic radars are detected and processed in a coherent manner to derive a set of angles used to triangulate the target position. Simulations are described including an approximate modelling of the bistatic radar cross-section. Analysis of different multistatic configurations is carried out. Further possible improvements of the concept are also introduced. View full abstract»

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  • Polarimetric classification of land cover for Glen Affric radar project

    Page(s): 404 - 412
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (2538 KB)  

    In recent years two polarimetric decompositions methods, the A/E method (Cloude and Pottier, 1997) and the three-component decomposition method (Freeman and Durden, 1998) have become the main methods of the polarimetric synthetic aperture radar data classification in radar imagery applications. In both methods the structural composition of the land cover is modelled using the main backscatter responses, as a function of the polarised channels, the level of energy received and the associated backscatter angles. To enhance the coherence in the polarimetric decompositions, data are generally multi-looked and de-speckled. The authors have applied and compared the 'Freeman' three-component decomposition followed by the Wishart complex classifier with the A/E decomposition algorithms to the de-speckled and edge-enhanced Glen Affric, fully polarimetric L-band radar data. The Glen Affric radar site was chosen for its extensive and diverse semi-natural woodlands of native Scots Pine, and its varied topography. The application results demonstrate the response of the radar classification from a semi-natural land cover on a rapid topography. View full abstract»

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  • Change detection for low-frequency SAR ground surveillance

    Page(s): 413 - 420
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (393 KB)  

    Change detection using ultra-wideband synthetic aperture radar (SAR) images in the low end of the VHF band is shown to provide excellent performance for detection of vehicle-sized objects in forest concealment. Two different change detection algorithms are discussed and their performance evaluated. The two algorithms are based on similar statistical hypothesis testing, but differ in that one operates on complex (coherent change detection) whereas the other uses magnitude (incoherent change detection) image data. Algorithm evaluation is performed using radar data acquired with the airborne CARABAS-II SAR in northern Sweden. The data were collected during a change detection experiment with concealed vehicles in boreal forests (stand volume ca. 100 m3/ha). Results show that coherent change detection gives slightly better performance using full spatial resolution of the images, whereas the incoherent change detection gives better performance when spatial averaging (2×2 resolution cells) is included. A comparison with detecting vehicles using only single-pass images shows an increase of false alarms of one to two orders of magnitude at the same probability of detection. View full abstract»

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  • KB-GLRT: exploiting knowledge of the clutter ridge in airborne radar

    Page(s): 421 - 428
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (165 KB)  

    Knowledge-based radar detection for space-time adaptive processing applications is addressed. At the design stage, the characteristic structure of the clutter ridge was taken account of and two decision rules were devised according to the generalised likelihood ratio test (GLRT) and the two-step GLRT criteria. The authors first deal with the case of a clutter ridge with integer slope and then discuss the more general framework of a non-integer slope. For the latter case only approximate GLRT detectors are provided due to the analytical difficulties connected with the exact solution of the problem. Analysis shows that the new knowledge-based systems can outperform some previously proposed adaptive schemes and can achieve a performance level very close to the optimum detector, which assumes the perfect knowledge of the clutter covariance matrix. View full abstract»

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  • Fast versus slow scan radar operation for coherent small target detection in sea clutter

    Page(s): 429 - 435
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (242 KB)  

    Small maritime surface targets can be difficult to distinguish from sea clutter in radar backscattered signals, but discrimination may be improved by using coherent detectors within the dwell time of a scanning radar. Non-coherent integration, coherent integration, the Kelly detector and the adaptive linear quadratic detector are considered. Target detectability may also be improved by combining the results of a single dwell across multiple scans. Overall target detection times of 2, 5 and 10 s are considered and the trade-off between within-scan dwell time and multiple scan processing gain is investigated. Analysis of high-range-resolution coherent X-band data of small boats reveals that faster scan rates with corresponding shorter dwell times provide improved target detection performance over slower scan rates and longer dwell times. 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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