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Radar, Sonar and Navigation, IEE Proceedings -

Issue 4 • Date Aug 2000

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Displaying Results 1 - 8 of 8
  • Complexity-reduced direction-of-arrival estimation method for highly correlated sources

    Page(s): 157 - 161
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (404 KB)  

    The paper presents an approach based on a preprocessing technique that allows previously known methods of reducing the complexity of subspace-based methods to be adapted to the case of highly correlated signals. Snapshot vectors are first preprocessed, and then used to compute the signal subspace of the spatially smoothed correlation matrix. The proposed method is a complexity-reduced version of the DEESE algorithm (Grenier et al., 1993). It gives better resolution in noisy environments than the common spatial-smoothing method with a relatively small increase in computational cost View full abstract»

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  • Triple-threshold radar-to-ESM correlation algorithm when each radar track is specified by different number of measurements

    Page(s): 177 - 181
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (408 KB)  

    Radar-to-ESM (electronic support measurement) correlation is one of the key subjects in military multisensor data fusion. Based on fuzzy synthetic function and statistical theory, a triple-threshold radar-to-ESM correlation algorithm is presented, which is suited for the situations where each radar track is specified by different number of measurements. The analytic expressions of the three thresholds are derived. Since the middle and low thresholds depend on the azimuth difference between the true ESM track and radar track, which varies with situations, and it is time-consuming to obtain the values of the two thresholds, the approximate solutions to the middle and high thresholds are also obtained. Simulation results show the feasibility of the algorithm View full abstract»

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  • Calculation of moments of complex Wishart and complex inverse Wishart distributed matrices

    Page(s): 162 - 168
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (428 KB)  

    The calculation of moments of complex Wishart and complex inverse Wishart distributed random matrices is addressed. In applications such as radar, sonar or seismics, complex Wishart and complex inverse Wishart distributed random matrices are used to model the statistical properties of complex sample covariance matrices and complex inverse sample covariance matrices. respectively. Moments of these random matrices are often needed, for example, in studies of the asymptotic properties of parameter estimates. A derivation of the probability density function of complex inverse Wishart distributed random matrices is given. Furthermore, strategies are outlined for the calculation of the moments of both complex Wishart and complex inverse Wishart distributed matrices View full abstract»

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  • Moving target feature extraction with polarisation diversity in the presence of arbitrary range migration and phase errors

    Page(s): 208 - 216
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (700 KB)  

    High range resolution (HRR) moving target indication (MTI) is increasingly important in many military and civilian applications such as the detection and classification of moving targets in strong clutter backgrounds. Meanwhile using polarisation diversity in radar systems has been shown to result in improved performance as compared with using only a single polarisation channel. The authors extract HRR moving target features with polarisation diversity in the presence of strong stationary clutter. The problem considered takes into account arbitrary range migration and phase errors, which may be induced by unknown target and platform motions as well as atmosphere turbulence and/or system instability. A relaxation-based algorithm is presented for the joint clutter suppression and super resolution target feature extraction and its performance is compared to the Cramer-Rao bound, the best performance bound an unbiased estimator can achieve. Numerical results are also provided to demonstrate the performance of the proposed algorithm View full abstract»

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  • Fractal approach for sea clutter generation

    Page(s): 189 - 198
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (844 KB)  

    Clutter is obtained by applying physical optics to a sea surface described by a fractal model. This approach gives two interesting advantages. It is possible to control sea, radar and geometry parameters so reproducing a realistic scenario in which the clutter signal is generated. The main drawback of the clutter stochastic models which generate statistical clutter-like random sequences without directly accounting for the operating conditions in which this clutter is expected, is overcome. Secondly, the fractal nature of the sea clutter is intrinsically taken into account through the fractal characterisation of the sea surface. This aspect leads to a rigorous theoretical study on the fractal nature of the sea clutter and is also useful in new remote sensing research concerning fractal analysis of clutter for classification and detection purposes. The clutter generator was finally validated by statistical analysis of the output data. The results show a statistical behaviour comparable with that obtained from experimental data in the literature View full abstract»

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  • Ambiguity elimination in HF FMCW radar systems

    Page(s): 182 - 188
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (796 KB)  

    Multiple waveform repetition frequency (WRF) is introduced as a solution to the range/Doppler ambiguity usually associated with high-frequency frequency-modulated continuous wave radars. The proposed pattern requires switching of WRFs while the target is being illuminated. The combination of WRFs is chosen to have a common multiple frequency greater than the expected target Doppler shift to resolve any Doppler shift ambiguities. An algorithm for the calculation of the Doppler shift of ambiguous targets is described. The performance of the new technique is evaluated by simulation. The results show that this technique can be used for ambiguity elimination of wideband ionospheric clutter View full abstract»

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  • Modulation identification of digital signals by the wavelet transform

    Page(s): 169 - 176
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (744 KB)  

    There is a need, for example in electronic surveillance, to determine the modulation type of an incoming signal. The use of the wavelet transform for modulation identification of digital signals is described. The wavelet transform can effectively extract the transient characteristics in a digital communication signal, yielding distinct patterns for simple identification. Three identifiers for classifying PSK and FSK, M-ary PSK and M-ary FSK are considered. Statistics for hypothesis testing are derived. When the carrier-to-noise ratio is low, the symbol period and synchronisation time are needed to improve identification accuracy. A method for estimating them from the wavelet transform coefficients is included. The performance of the identifier is investigated through simulations View full abstract»

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  • Design of SLB systems in the presence of correlated ground clutter

    Page(s): 199 - 207
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (716 KB)  

    Impulsive interference might increase the number of false alarms in a surveillance radar. The sidelobe-blanking (SLB) device, used in connection with the radar system, reduces the number of false alarms when the interference impinges on the antenna sidelobes. The paper describes how to design an SLB system operating in correlated Gaussian clutter with known Doppler spectrum plus white Gaussian thermal noise and impulsive interference. Closed-form expressions of the probability of false alarm, the probability of blanking a target received in the main lobe, and the probability of blanking a coherent repeater interference (CRT) are also derived for two statistical models of target/CRI, namely: Swerling-0 (known amplitude and random phase), and Swerling-I (random amplitude and random phase) 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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