Online ISSN
1751-9683
Print ISSN
1751-9675
IET Signal Processing
Volume 4, Issue 1, February 2010
Volumes & issues:
Volume 4, Issue 1
February 2010
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- Author(s): T. Hasan and Md.K. Hasan
- Source: IET Signal Processing, Volume 4, Issue 1, p. 1 –11
- DOI: 10.1049/iet-spr.2008.0114
- Type: Article
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A new minimum mean square error (MMSE) estimator for discrete cosine transform (DCT) domain speech enhancement considering the two state possibilities of signal and noise DCT coefficients, the constructive and destructive interference, is proposed. Given proper identification of these events are possible, an optimum non-linear MMSE estimator can be derived considering the conditional events. Compared to the previously reported dual-gain multiplicative filters, the proposed estimator demonstrates superior theoretical and experimental performance with respect to mean square error (MSE) improvement and other objective quality measures. - Author(s): M.F. Flanagan ; M. McLaughlin ; A.D. Fagan
- Source: IET Signal Processing, Volume 4, Issue 1, p. 12 –21
- DOI: 10.1049/iet-spr.2008.0141
- Type: Article
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Adaptive algorithms which perform minimum-phase–all-pass (MP–AP) decomposition of a finite impulse response system are proposed. The first algorithm models the MP component of the system as a lattice filter cascaded with a gain stage. The algorithm has a low misconvergence probability, and is capable of detecting misconvergence during or after adaptation. Two further algorithms are proposed based on the theory of the bicepstrum. One adaptively solves a finite linear system of equations and the other an augmented nonlinear system. The first has an error sensitive to the proximity of the system zeros to the unit circle, whereas the second, although more computationally intensive, may approach the exact MP–AP decomposition given a sufficient number of iterations. These real-time MP–AP decomposition algorithms have applications in the stabilisation of compound precoding, which is a pre-equalisation technique included as an option in the V.92 high-speed modem standard. - Author(s): G. Jovanovic Dolecek and S.K. Mitra
- Source: IET Signal Processing, Volume 4, Issue 1, p. 22 –29
- DOI: 10.1049/iet-spr.2008.0160
- Type: Article
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A simple two-stage multiplierless cascaded–integrator–comb (CIC)-based decimator is presented. The first stage is a cascaded CIC filter whereas the second stage is a cascaded CIC filter and a second-order multiplierless compensator. The proposed decimator can be realised without filtering at high input rate by making use of the polyphase decomposition of the comb filter in the first stage. The proposed filter exhibits high aliasing attenuation and a low passband droop. The design parameters are the decimation factors, M1 and M2, numbers of cascaded CIC filters L and K, and parameter b of the compensator. - Author(s): A.Y. Kibangou and G. Favier
- Source: IET Signal Processing, Volume 4, Issue 1, p. 30 –44
- DOI: 10.1049/iet-spr.2008.0138
- Type: Article
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In this study, we show that the minimum mean square estimate (MMSE) of the parameters of a fifth-order Volterra model can be obtained in closed-form when the input is independent and identically distributed (i.i.d). The derived closed-form expressions of the kernel coefficients can be used for identifying Volterra systems with arbitrary memory. Some simulation results are presented to illustrate the proposed identification method. - Author(s): H.-J. Liu ; Z. Liu ; W.-L. Jiang ; Y.-Y. Zhou
- Source: IET Signal Processing, Volume 4, Issue 1, p. 45 –54
- DOI: 10.1049/iet-spr.2008.0240
- Type: Article
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To deal with the problem of emitter identification (EID) caused by the measurement uncertainty of emitter feature parameters and to realise the automatic updating of the emitter database, which is usually used as emitter templates in identification processing, a vector neural network based incremental learning (VNNIL) approach for EID is proposed. This method combines the vector neural networks (VNNs) and the ensemble-based incremental learning (Learn++) algorithm. The VNN is adopted to construct a weak classifier and the Learn++ is used to generate ensembles of the weak classifiers. Considering that the VNN can realise the non-linear mapping between the interval-value input data and the interval-value output emitter types, and that the Learn++ can update the emitter database automatically, the VNNIL treats the two mentioned problems above as a single one and realises EID and parameters updating at the same time. A number of simulations are presented to demonstrate the identification and updating capability of the VNNIL algorithm. As shown in the simulation results, the VNNIL algorithm not only possesses a better learning and identification capability, but also achieves a better noise adaptability. - Author(s): N. Kalyanasundaram and P. Palanisamy
- Source: IET Signal Processing, Volume 4, Issue 1, p. 55 –68
- DOI: 10.1049/iet-spr.2008.0258
- Type: Article
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A new approach for active-sonar target detection and bearing estimation from a mobile two-dimensional array of sensors operating in a predominantly noisy environment is presented. Sensor-level adaptive noise cancellation featuring an unconventional method for reference-noise estimation is the key preprocessing step in the proposed approach. A signal-subspace algorithm resulting from two-stage optimisation based on a generalised eigendecomposition of the signal plus (residual) noise covariance matrix is employed to estimate the bearing of the detected target. Simulation results conclusively demonstrate that the proposed scheme is capable of performing target detection and the subsequent two-dimensional bearing estimation with a high degree of reliability at signal-to-noise power ratios as low as −70 and −40 dB, respectively. - Author(s): H. Song ; W.-A. Zhang ; L. Yu
- Source: IET Signal Processing, Volume 4, Issue 1, p. 69 –77
- DOI: 10.1049/iet-spr.2008.0112
- Type: Article
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This work studies the H∞ filtering problem for a class of discrete-time network-based systems with communication constraints. The considered plant has multiple outputs and only one of them can be sent to the filter at each transmission instant because of the communication constraints. A new compensation scheme is proposed, upon which the filtering error system is modelled as a switched system by considering mode-dependent filters. Sufficient conditions are derived for the filtering error system to be exponentially stable and ensure a prescribed H∞ disturbance attenuation level bound by using the average dwell-time method. Based on the derived conditions, a design procedure for the H∞ filter is also presented. An illustrative example is given to show the effectiveness of the proposed method. - Author(s): P.Y. Qiu ; Z.T. Huang ; W.L. Jiang ; C. Zhang
- Source: IET Signal Processing, Volume 4, Issue 1, p. 78 –88
- DOI: 10.1049/iet-spr.2009.0033
- Type: Article
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Direct sequence spread spectrum (DSSS) signals are now widely used for communications. According to the relationship between spreading factor and code length, the DSSS signals can be divided into two types: the short-code (SC) and the long-code (LC) DSSS. For the cooperative receivers, the above type information is known in advance. However, under the non-cooperative contexts, such information becomes one of the unknown parameters of interest. To extract this information, a blind algorithm that is based on the second-order statistics of the matrix norms of the signal correlation matrices is proposed in this study. A set of correlation matrices is constructed from the received signal samples following which the matrix norm of each correlation matrix is computed and normalised by the maximum. Then, by comparing the variance of the normalised matrix norms with a preset threshold, the type of the received DSSS signal can be identified. Simulation results verify the capability of the proposed method in various scenarios, such as multipath fading channel and multiple access interference. - Author(s): A.E. El-Mahdy
- Source: IET Signal Processing, Volume 4, Issue 1, p. 89 –101
- DOI: 10.1049/iet-spr.2009.0038
- Type: Article
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The performance of a multicarrier direct sequence code division multiple access (MC-DS-CDMA) system in fading environment has been extensively analysed in the literatures. The analysis that is available in the literatures did not take into account the impact of jamming and channel estimation errors on the performance of the system. In this study, closed-form expressions of the average bit error probability (BEP) of the MC-DS-CDMA system with channel estimation errors in the presence of partial band, broadband and multitone jamming are derived in a Rayleigh fading channel. The analysis shows that the magnitude of the normalised correlation between the actual and the estimated complex fading channel gain, A, greatly affects the performance of the MC-DS-CDMA system. For large signal-to-noise ratio, the average BEP with A=1 and without multiple access interference (MAI) tends to zero. When A≠1, the BEP of the system exhibits an error floor even without MAI. This error floor increases as the number of users increases. It is also shown that increasing the number of the system subcarriers enhances the system performance against jamming. - Author(s): T.-B. Deng
- Source: IET Signal Processing, Volume 4, Issue 1, p. 102 –111
- DOI: 10.1049/iet-spr.2008.0125
- Type: Article
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p.
102
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Existing finite-support interpolators are derived from continuities in the time-domain. In this study, the authors optimally design a quadratic interpolator using two second-degree piecewise polynomials in the frequency-domain. The optimal coefficients of the piecewise polynomials are found by minimising the weighted least-squares error between the ideal and actual frequency responses of the quadratic interpolator subject to a few constraints. Adjusting the weighting functions in different frequency bands can yield accurate frequency response in a specified passband and even can ignore ‘don't care’ bands so that various quadratic interpolators can be designed for interpolating various discrete signals containing different frequency components. One-dimensional and two-dimensional examples have shown that the quadratic interpolator can achieve much higher interpolation accuracy than the existing interpolators for wide-band signals, and various images have been tested to verify that the quadratic interpolator can achieve comparable interpolation accuracy as the Catmull–Rom cubic for narrow-band signals (images), but the computational complexity can be reduced to about 70%. Therefore both narrow-band and wide-band signals can be interpolated with high accuracy.
MMSE estimator for speech enhancement considering the constructive and destructive interference of noise
Gradient-adaptive algorithms for minimum-phase-all-pass decomposition of a finite impulse response system
Two-stage CIC-based decimator with improved characteristics
Identification of fifth-order Volterra systems using i.i.d. inputs
Incremental learning approach based on vector neural network for emitter identification
Active bearing estimation from a mobile two-dimensional array of sensors
H∞ filtering of network-based systems with communication constraints
Blind classification of the short-code and the long-code direct sequence spread spectrum signals
Error probability analysis of multicarrier direct sequence code division multiple access system under imperfect channel estimation and jamming in a Rayleigh fading channel
Frequency-domain weighted-least-squares design of quadratic interpolators
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