IEE Proceedings - Radar, Sonar and Navigation
Volume 153, Issue 5, October 2006
Volumes & issues:
Volume 153, Issue 5
October 2006
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- Author(s): Z.-T. Huang and Y.-Y. Zhou
- Source: IEE Proceedings - Radar, Sonar and Navigation, Volume 153, Issue 5, p. 381 –388
- DOI: 10.1049/ip-rsn:20045049
- Type: Article
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p.
381
–388
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Single-cycle time-difference-of-arrival estimator utilises signal's cyclostationarity property of only one cycle frequency. A new approach exploiting the signal's cyclostationarity property of more than one cycle frequency is introduced. Compared with the single-cycle estimator, the method can reduce more estimation variance. The qualitative discussion of the performance of multi-cycle estimator is given and the performances of different estimators in various environments are quantitatively measured in terms of root-mean-squared errors from Monte Carlo simulations. Simulation results demonstrate the effectiveness and superiority of multi-cycle estimator in comparison with the single-cycle estimator and the conventional cross-correlation one. - Author(s): T. Jin ; Z. Zhou ; W. Chang
- Source: IEE Proceedings - Radar, Sonar and Navigation, Volume 153, Issue 5, p. 389 –395
- DOI: 10.1049/ip-rsn:20045050
- Type: Article
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p.
389
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In ultra-wideband synthetic aperture radar (UWB SAR) imaging, scatterers often perform the frequency- and aspect angle-dependent reflectivity characteristic, which is usually neglected in traditional imaging processing. A novel UWB SAR time-frequency representation image formation (TFRIF) is proposed to retrieve the frequency- and aspect angle-dependent information, which is valuable in target detection. Based on the TFRIF, two fusion schemes are studied: pixel level fusion (PLF) and decision level fusion (DLF). Based on the analytical expressions, it is concluded that TFRIF can extract the reflectivity pattern information with high precision and little sacrifice of the spatial resolutions. Quantitative analyses of spatial resolutions and detectability improvement of the proposed fusion schemes are tested on airborne UWB SAR data. The real data results validate the proposed TFRIF and its associated PLF and DLF schemes. - Author(s): M. Shinriki ; H. Takase ; R. Sato ; H. Susaki
- Source: IEE Proceedings - Radar, Sonar and Navigation, Volume 153, Issue 5, p. 396 –402
- DOI: 10.1049/ip-rsn:20050094
- Type: Article
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p.
396
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A radar range resolution is generally determined by its transmitted pulse width and is thus a constant parameter unrelated to the detection range. However, a method has been proposed for greatly improving a radar range resolution by using signal-processing techniques to reduce the received pulse width at the expense of a high target signal-to-noise ratio. In this method, an autocorrelation output is first obtained from a time-series representation of the received signal, and this autocorrelation output is then processed using a least-squares error-shaping filter. This creates a corresponding increase in the bandwidth of the principal frequency spectrum, thereby improving the range resolution. The relationship between this spectral distribution and the range side-lobes in cases where the transmitted signal is a simple pulse or a plain phase-modulated wave is investigated. The interference cancelling effect achieved when a radar based on the proposed scheme receives interference is also investigated. - Author(s): E.S. Lohan ; A. Lakhzouri ; M. Renfors
- Source: IEE Proceedings - Radar, Sonar and Navigation, Volume 153, Issue 5, p. 403 –408
- DOI: 10.1049/ip-rsn:20060005
- Type: Article
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p.
403
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The authors introduce a new class of modulation, the complex double-binary-offset-carrier (CDBOC) modulation class, which covers most of the modulation types proposed so far for Galileo and GPS signals, namely the binary and quaternary phase shift keying, sine BOC, cosine BOC and alternate BOC modulations. At the same time, the CDBOC class provides a more general framework, with the potential for new applications of wide-band code division multiple access systems and/or future satellite navigation systems. The theoretical derivations of the power spectral density and the auto-correlation function of the CDBOC-modulated signals are introduced, and the theoretical analysis is compared with the results obtained via simulations. The advantage of our method in the context of Galileo and GPS signals is its simplicity and the fact that it provides unified analytical formulas for most of the existent GPS/Galileo signals. - Author(s): D. Bourgeois ; C. Morisseau ; M. Flécheux
- Source: IEE Proceedings - Radar, Sonar and Navigation, Volume 153, Issue 5, p. 409 –416
- DOI: 10.1049/ip-rsn:20050100
- Type: Article
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p.
409
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As over-the-horizon radar (OTHR) uses ionosphere reflection to detect and track targets, they are faced with a possible appearance of multi-paths and difficulties in estimating the target's ground location. The multi-quasi-parabolic (MQP) model is a sophisticated ionosphere model from which the electromagnetic waves' propagation can be deduced, as long as the measurement of the elevation angle is known. As the French OTHR Nostradamus measures this angle, the use of this model is proposed to improve target-tracking. This model is directly taken into account in the tracking algorithm equations. Here, the target's ground location estimation is specifically tackled and a method is proposed to handle MQP parameters even if elevation angle measurement resolution is poor. The proposed algorithm, based on a particle filter, enables the estimated model parameters to be dealt with and is able, in some circumstances, to ameliorate their estimations. This approach, applied to OTHR Nostradamus, is compared to a geometric one with numerical simulations and a real data example. - Author(s): A.R. Runnalls
- Source: IEE Proceedings - Radar, Sonar and Navigation, Volume 153, Issue 5, p. 417 –426
- DOI: 10.1049/ip-rsn:20045107
- Type: Article
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p.
417
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A common sonobuoy configuration comprises two horizontal dipoles mounted orthogonally together with an omnidirectional sensor. Under the assumption that, within a narrow frequency band of interest, the acoustic power impinging on the sonobuoy consists of uncorrelated Gaussian noise processes, the author examines how data collected by the sensor can be used to infer the directional distribution of the incident power, as characterised by its spherical harmonic coefficients. The results cover arbitrary directional distributions and are applicable to small, as well as large, sample sizes. The form of the likelihood function for the spherical harmonic coefficients, as required for Bayesian inference methods such as particle filtering, is particularly examined. Specific attention is given to the case of a single point source superimposed on azimuthally isotropic noise. In this case it is shown that the maximum likelihood estimator for target bearing differs from, and can be considerably more efficient than, the bearing estimator traditionally used for this sensor configuration. - Author(s): M. Cherniakov ; R.S.A.R. Abdullah ; P. Jančovič ; M. Salous ; V. Chapursky
- Source: IEE Proceedings - Radar, Sonar and Navigation, Volume 153, Issue 5, p. 427 –437
- DOI: 10.1049/ip-rsn:20050028
- Type: Article
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p.
427
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Experimental study is undertaken of the feasibility of forward scattering radar (FSR) and its application to automatic ground target classification. The radar itself, fundamental theoretical analysis, target recognition algorithm and the target's classification subsystem are introduced. For target recognition, the effect of shadow inverse synthetic aperture radar is used. The radar experimental set-up and experimentation results are discussed. For classification, a system is proposed, which extracts features from the radar measurements by using Fourier transform and principle component analysis and uses a nearest neighbour classifier. Speed estimation in FSR is also introduced. By analysing 850 experimentally obtained car signatures, the performance of the system is evaluated and the effectiveness of the system is confirmed. The limitations of the work and its future are also discussed. - Author(s): L. Øyehaug and R. Skartlien
- Source: IEE Proceedings - Radar, Sonar and Navigation, Volume 153, Issue 5, p. 438 –444
- DOI: 10.1049/ip-rsn:20050104
- Type: Article
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p.
438
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Ensemble-averaged randomly scaled radar or sonar pulses are considered and the statistical theory for the corresponding phase and amplitude modulations are developed. Random scaling expresses varying radar cross-sections for scattering objects or varying antenna gain of a sweeping emitter. The noise variance of the modulations depends on the distribution function of the scaling, and how to minimise the variance by rejecting pulses below a certain amplitude threshold is shown. The theory is asymptotic in the sense that it is more accurate for increasing signal-to-noise ratios (SNRs). In a test case with uniformly distributed scaling, sufficient accuracy is reached for an average SNR larger than ∼5 for the phase average and ∼15 for the amplitude average. - Author(s): H. Su ; H. Liu ; P. Shui ; S. Zhang ; Z. Bao
- Source: IEE Proceedings - Radar, Sonar and Navigation, Volume 153, Issue 5, p. 445 –453
- DOI: 10.1049/ip-rsn:20050069
- Type: Article
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p.
445
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A novel high-frequency surface wave radar (HFSWR) has been proposed, which is based on the principles of synthetic impulse and aperture processing. It uses multiple omnidirectional transmit antennae to simultaneously transmit a set of orthogonal waveforms, and the echoed signals are received and processed by one or multiple reception arrays. Although the transmit beam pattern is omnidirectional, by proper processing, the received signal multiple equivalent directional transmit beam patterns can be simultaneously formed. The signal processing scheme to obtain equivalent directional transmit beam pattern is investigated in detail. Considerations for system parameter selection to achieve an overall best system performance are proposed and discussed. In particular, for the novel HFSWR, target range and angle estimates are coupled together due to the orthogonality of the transmitted waveforms. A necessary and sufficient condition on the transmit antenna array geometry and transmit frequencies, which ensures that target range and angle estimates are uncoupled, is presented. - Author(s): M. Greco ; F. Gini ; A. Farina ; V. Ravenni
- Source: IEE Proceedings - Radar, Sonar and Navigation, Volume 153, Issue 5, p. 454 –459
- DOI: 10.1049/ip-rsn:20050080
- Type: Article
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p.
454
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The analysis of jamming signals emitted by electronic countermeasure (ECM) systems after phase quantisation, performed by radio frequency digital memory devices, and after introduction of increasing time delay, is approached. The analysis shows the exact expression of the spectrum of a phase-quantised jamming signal when the quantisation levels are equally spaced. The spectrum of the signal presents a main term that is simply an attenuated version of the signal received by the ECM system, and spurious terms whose amplitude and position depend on the number of quantisation levels. The effect of time delay quantisation introduced by range gate pull-off devices is analytically evaluated, in combination to the phase quantisation. Results show that this second distortion can be generally neglected with respect to the spurious terms because of the phase quantisation, particularly when the number of phase quantisation bits is low. - Author(s): K. Cheikh and F. Soltani
- Source: IEE Proceedings - Radar, Sonar and Navigation, Volume 153, Issue 5, p. 460 –466
- DOI: 10.1049/ip-rsn:20050103
- Type: Article
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p.
460
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Radar signal detection is a complex task that is generally based on conventional statistical methods. In real applications, these methods require a lot of computing to estimate the clutter parameters and that they are optimal only for one type of clutter distribution. Recently, artificial neural networks (ANNs) have been used as a means of signal detection. Following on from this work, the authors consider the problem of radar signal detection using ANNs in a K-distributed environment. Two training algorithms are tested, namely, the back-propagation algorithm, and genetic algorithms for a multi-layer perceptron (MLP) architecture and also for the radial basis function architecture. The simulation results show that the MLP architecture outperforms the classical cell-averaging constant false alarm rate and order statistics constant false alarm rate detectors.
Multi-cycle estimator for time-difference-of-arrival (TDOA) and its performance
Ultra-wideband synthetic aperture radar time-frequency representation image formation
Multi-range-resolution radar using sideband spectrum energy
Complex double-binary-offset-carrier modulation for a unitary characterisation of Galileo and GPS signals
Over-the-horizon radar target tracking using multi-quasi-parabolic ionospheric modelling
Likelihood function for a simple cardioid sonobuoy
Automatic ground target classification using forward scattering radar
Reducing the noise variance in ensemble-averaged randomly scaled sonar or radar signals
HFSWR based on synthetic impulse and aperture processing
Effect of phase and range gate pull-off delay quantisation on jammer signal
Application of neural networks to radar signal detection in K-distributed clutter
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