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Radar and Signal Processing, IEE Proceedings F

Issue 3 • Date Jun 1991

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Displaying Results 1 - 14 of 14
  • Design of contiguous RF filterbanks with application in channelised receivers

    Page(s): 289 - 292
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (260 KB)  

    Design techniques for miniature contiguous filterbanks for use in channelised receivers operating in high pulse density environments are presented. These devices use a new prototype transfer function with a maximally flat impulse response which minimises ringing in the time domain caused by pulsed signals. The devices are designed to combine small size with high performance and good manufacturing tolerances. The devices are constructed using a hybrid of printed circuit and lumped element techniques. Measured results for 10 channel and 27 channel devices operating at a 1 GHz centre frequency with channel bandwidths of 20 MHz are presented View full abstract»

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  • Suboptimal real-time frequency/incident-angle estimator for multiple radar pulses

    Page(s): 247 - 254
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (508 KB)  

    A method is presented that provides numerical estimates of properly paired frequency and incident angles for an arbitrary number of sinusoidal radar pulses incident on a linear array. The key element of the method is a two-stage suboptimal technique that estimates the angle of arrival of a pulse by using the output of two antenna elements and a previously calculated value of paired frequency. A method of extending the two-element method to multiple elements, by using a noise protected modification of the Chinese remainder theorem (CRT) is also advanced. Owing to its simplicity, the algorithm is appropriate to real-time processing View full abstract»

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  • Radar absorbers: better by design

    Page(s): 223 - 228
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (356 KB)  

    The radar cross section of a structure can be controlled by shaping it and either covering it with radar absorbing materials (RAM) or manufacturing the structure from absorbent engineering materials. A radar absorbing layer can be designed from a knowledge of the complex permeabilities and permittivities of the constituent materials and their frequency dependence. Constrained (in waveguide), and free field (open resonator) techniques for measuring these properties are described and results presented for a ferromagnetic material at microwave frequencies. A computer design methodology is discussed and results are compared with practical absorbers View full abstract»

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  • Target tracking algorithms for phased array radar

    Page(s): 255 - 262
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (572 KB)  

    Phased array radar have an additional degree of freedom compared with track-while-scan radar, in that a variable update time may be used in the former. On detection of a manoeuvre, the update time may be reduced leading to an improved tracking accuracy. It has been shown how a variable update time may be incorporated into the αβ filter, the value of this update time being dependent on the magnitude of the residual. The algorithm of Cohen (1986) is tested by application of Monte-Carlo simulations to a wide variety of target tracks. Additional strategies in choosing the update time are also examined. The dependence of the mean square estimation errors and the mean update times are investigated for a range of parameters of the algorithm. It is concluded that in choosing the parameters of the algorithm, there is a trade-off between keeping the estimation errors low and restricting the mean update time from becoming excessively small View full abstract»

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  • Processing of signum coded SAR signal: theory and experiments

    Page(s): 192 - 198
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (468 KB)  

    A synthetic aperture radar raw signal which is passed through an ideal limiter is considered. Only the information about the zero crossings is provided because of this process. The output signal is processed in the conventional way. It is then sampled at a rate consistent with the original bandwidth. The image does not exhibit any applicable degradation. The full theory of the operation of this signum coded synthetic aperture radar is provided, as well as a number of confirming experiments View full abstract»

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  • Generation and properties of synthetic aperture polar diagrams for use in DF systems

    Page(s): 229 - 240
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (928 KB)  

    A synthetic aperture method of generating polar diagrams with shapes which conform to Bessel functions rather than the more familiar sin x/x form is described. The method can be used to generate, using a circular array, polar diagrams for use in Doppler DF and VOR beacon systems. This generation avoids the amplitude limiting employed in conventional forms of these systems. The method is applicable to linear arrays and can be used in microwave landing aids. In this application, a very good side lobe performance superior to the (sin x)/x form is obtainable. The site error suppression performance of a Doppler DF having a synthetic aperture is compared with a conventional Doppler system. Both are compared with a standard based on utilisation of a (sin x)/x lobe structure. No practical work on a DF system has been undertaken, although the generation has been used in another project; some measured results are given in this respect. The main conclusion is that the generation will enable the Doppler DF concept to eliminate the disadvantage of being prone to considerable inaccuracies, as caused by abnormally strong reflections View full abstract»

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  • Recursive SMLR deconvolution algorithm for Bernoulli-Gaussian signals

    Page(s): 263 - 266
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (216 KB)  

    In the past decade, many detection and estimation algorithms have been reported for estimating a desired Bernoulli-Gaussian signal which was distorted by a linear time-invariant system. The well known Kormylo and Mendel's (1982) single most likely replacement (SMLR) algorithm, which works well and has been successfully used to process real seismic data, is an offline signal processing algorithm. The paper proposes a recursive SMLR algorithm which has online data processing capabilities and requires much less computational effort than Chi and Mendel's (1984) recursive algorithm and Goussard and Demoment's (1989) recursive algorithm. Simulation results show good performance View full abstract»

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  • Tracking technique for manoeuvring target with correlated measurement noises and unknown parameters

    Page(s): 278 - 288
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (576 KB)  

    The problem of tracking a manoeuvring target with sequentially correlated measurement noise is considered in the paper. Using Singer's method to model the manoeuvring target, the correlated measurement noise can be decorrelated by reformulating the measurement equation such that the conventional Kalman filter can be directly applied in this tracking problem. An analytical error analysis for this processing is derived. If some of the parameters are unknown, the conventional innovation correlation method can usually be employed to estimate these parameters adaptively. This method assumes that the measurement noise is white. If the measurement noise is sequentially correlated, this technique is not valid and the parameters can not be estimated with sufficient accuracy to obtain the desired tracking performance. By considering the effect of noise correlation, a modified computationally efficient method known as a multiple-level estimator is presented to improve the performance in estimating the unknown parameters in the presence of correlated measurement noise View full abstract»

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  • High resolution RCS measurements of boats

    Page(s): 218 - 222
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (268 KB)  

    The radar cross-sections (RCS) at I-band for two boats were measured as a function of range and aspect angle by illuminating the boats with 9.3 GHz horizontally polarised microwaves using a purpose built coherent pulsed radar. The total RCS of a mean profile was determined for each aspect angle at which RCS profiles were obtained. The mean of these total RCS values, over all aspect angles, was 33 dBm 2 for the water/fuel lighter HMAS Warrigal, and 37 dBm2 for the torpedo recovery boat HMAS Tuna View full abstract»

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  • Optimised array antenna nulling with phase-only control

    Page(s): 241 - 246
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (276 KB)  

    The pointing direction gain of a linear phased array antenna is maximised with the constraints of phase-only control at the N antenna elements and the imposition of J nulls at angles θ1, θ2. . ., θJ from the array normal. The specification of J nulling angles requires the a priori knowledge of the directions of the emitter sources. This maximisation problem with constraints is reduced to 2J +2 nonlinear equations which can be solved via a vector Newton algorithm to yield the N complex antenna weights in terms of the 2J+2 unknowns. Examples are given for a 20 element array with uniform and Hamming amplitude weighting and the imposition of as many as five nulling angles. Examples of mainbeam nulling are also given View full abstract»

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  • Use of difference channel information for detection in monopulse radars

    Page(s): 199 - 210
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (888 KB)  

    The problem of target detection and acquisition by a monopulse tracking radar is considered. This problem is conventionally addressed using only information in the sum beam. The additional information available in the difference channels may be utilised to give improved performance. Two possible realisations of this concept are presented and analysed in some detail, namely linear combinations of the sum and difference channels, and detection based on the complex indicated angle. Other possibilities are also mentioned as possible areas for future work View full abstract»

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  • Polarisation behaviour of ground clutter during dwell time

    Page(s): 211 - 217
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (452 KB)  

    Analyses the behaviour of ground clutter during dwell time in a low-resolution radar. The analysis is made with reference to measurements made through a pulse radar using right-handed circular polarisation at transmit and two orthogonally circularly polarised channels on reception. Symmetric and asymmetric distribution of polarisation with respect to its average is pointed out for two different types of ground clutter, the `clustered clutter' and the `distributed clutter.' Suitable parameters are defined and evaluated for statistical analysis of the experimental data to characterise and classify the observed phenomena. Frequent scan-to-scan stationarity of ground clutter polarisation is highlighted, which makes the statistical analysis meaningful for the application of suitable adaptive polarisation filtering techniques for ground clutter rejection View full abstract»

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  • Multipolarisation FM-CW Doppler radar signal processing for nondistributed targets

    Page(s): 185 - 191
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (452 KB)  

    The Delft FM-CW radar is used to characterise radar targets based on their polarisation parameters and Doppler velocity. Dedicated polarisers allow the radar system to have one receiver only. The domain of the polarisation information interferes with the domain of the Doppler-velocity information. To split these domains and to retrieve the target parameters, a specific processing approach has been developed. The method has been implemented to run on one or more array processors, which are used as preprocessing units on a host computer. Besides the mathematical outlines of the method, the structure and organisation of the processing units are discussed in the paper. Finally, some preliminary results of real-time performance measurements are shown View full abstract»

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  • Adaptive signal parameter estimation and classification technique

    Page(s): 267 - 277
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (696 KB)  

    A new technique, adaptive signal parameter estimation and classification technique (ASPECT), is presented for use in both coherent and noncoherent signal environments. Unlike superresolution techniques employing spatial smoothing preprocessing schemes, ASPECT is not restricted to linear arrays. ASPECT is based on an adaptive rotation of an initial subspace up to the point at which the rotated subspace coincides with the true signal subspace. The number of incident signals together with information relating to their position, etc., is provided by the algorithm. Computer simulations in support of the theory are presented View full abstract»

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Aims & Scope

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

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