It is usual to set a single-point noise controller at each point in order to cancel noises at multiple cancelling points. How should we adapt controllers in such a case? The easiest way is to let them work individuall...
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It is usual to set a single-point noise controller at each point in order to cancel noises at multiple cancelling points. How should we adapt controllers in such a case? The easiest way is to let them work individually, though it is possible to use all the error signals for one controller. In this case, there is a problem that the controllers do not necessarily converge. In this paper, we consider the conditions of the paths under which the controllers converge when they work individually.
This paper proposes new algorithms for adaptive FIR filters. The proposed algorithms provide both fast convergence and small final misadjustment with an adaptive step size even under an interference to the error. The ...
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This paper proposes new algorithms for adaptive FIR filters. The proposed algorithms provide both fast convergence and small final misadjustment with an adaptive step size even under an interference to the error. The basic algorithm pays special attention to the interference which contaminates the error. To enhance robustness to the interference, it imposes a special limit on the increment/decrement of the step-size. The limit itself is also varied according to the step-size. The basic algorithm is extended for application to nonstationary signals. Simulation results with white signals show that the final misadjustment is reduced by up to 22 dB under severe observation noise at a negligible expense of the convergence speed. An echo canceler simulation with a real speech signal exhibits its potential for a nonstationary signal.
In this article, an adaptive beamforming system based on the augmented complex least mean square algorithm is analysed. In this approach, the adaptive filter is used as a widely linear system. The second-order statist...
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In this article, an adaptive beamforming system based on the augmented complex least mean square algorithm is analysed. In this approach, the adaptive filter is used as a widely linear system. The second-order statistical information of the signals involved in the array is exploited. Under this consideration, the ability of the adaptive array to minimize the effects of interferences and complex white noise could be enhanced. The equations for the optimal weights and the array factor are derived for the proposed beamforming system. Computer simulations have been performed to evaluate the performance of the adaptive array, and the results were compared with two of the most common standard adaptive beamforming algorithms: the least mean square and recursive least square. The numerical simulations show that the proposed adaptive array has a better performance in time and spatial domain as compared to the classical beamforming systems.
Based on the ideas of the set-membership identification, we present in this paper variable gain least mean-square (lms) and weighted recursive least-squares (WRLS) algorithms. It is shown that the proposed algorithms ...
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Based on the ideas of the set-membership identification, we present in this paper variable gain least mean-square (lms) and weighted recursive least-squares (WRLS) algorithms. It is shown that the proposed algorithms possess a fast tracking ability to the variations of the parameter and at the same time are less sensitive to noise leading to a smooth steady state. (C) 2000 Elsevier Science Ltd. All rights reserved.
This paper presents a very simple and cheap off-line technique that is able to evaluate the aluminum electrolytic capacitors condition. Aluminum electrolytic capacitors equivalent circuit is composed by an internal re...
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This paper presents a very simple and cheap off-line technique that is able to evaluate the aluminum electrolytic capacitors condition. Aluminum electrolytic capacitors equivalent circuit is composed by an internal resistance and a capacitance. The capacitors internal resistance increases with aging while the capacitance decreases. Manufacturers define the end of life limit of the capacitor when its internal resistance doubles its initial value or the capacitance changes more than 20% when it is compared with the initial one. The proposed technique evaluates the capacitor condition through the identification of both capacitor internal resistance and capacitance. To compute both capacitor internal resistance and capacitance a very simple, cheap, and practical experimental setup is proposed.
In this study, a new non-iterative adaptive beamforming (ABF) algorithm for the signal-to-interference and noise ratio (SINR) enhancement is proposed. It is based on a combination between the direction of arrival (DOA...
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In this study, a new non-iterative adaptive beamforming (ABF) algorithm for the signal-to-interference and noise ratio (SINR) enhancement is proposed. It is based on a combination between the direction of arrival (DOA) estimation and the method of moments (MoM). The proposed algorithm is denoted as DM/ABF which stands for DOA and MoM-based ABF. The DOA is used to provide accurate estimates for the directions of the desired and interfering signals. On the basis of the estimated DOAs, a dedicated shaped pattern version of the ordinary pattern is created and applied as the desired input to the MoM algorithm. The MoM is used for shaped pattern synthesis to estimate the weights vector required to provide deep nulls toward the interfering signals and directs the main beam toward the desired signal. In this case, the weights vector does not update iteratively at each received signal sample as in case of least mean square (lms) and recursive least squares (RLSs) algorithms, but it is updated only when the estimated DOAs of the desired and interfering signals are changed. Furthermore, a large number of close nulls can be produced without the need for additional antenna elements compared with other algorithms.
The performance of the modified adaptive conjugate gradient (CG) algorithms based on the iterative CG method for adaptive filtering is highly related to the ways of estimating the correlation matrix and the cross-corr...
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The performance of the modified adaptive conjugate gradient (CG) algorithms based on the iterative CG method for adaptive filtering is highly related to the ways of estimating the correlation matrix and the cross-correlation vector. The existing approaches of implementing the CC algorithms using the data windows of exponential form or sliding form result in either loss of convergence or increase in misadjustment. This paper presents and analyzes a new approach to the implementation of the CG algorithms for adaptive filtering by using a generalized data windowing scheme. For the new modified CC algorithms, we show that the convergence speed is accelerated, the misadjustment and tracking capability comparable to those of the recursive least squares (RLS) algorithm are achieved. Computer simulations demonstrated in the framework of linear system modeling problem show the improvements of the new modifications. (c) 2008 Elsevier B.V. All rights reserved.
This work presents a new mixed (2,p-like)-norm penalized least mean squares (lms) algorithm for block-sparse system identifications where the nonzero coefficients in the impulse response vector of unknown systems are ...
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This work presents a new mixed (2,p-like)-norm penalized least mean squares (lms) algorithm for block-sparse system identifications where the nonzero coefficients in the impulse response vector of unknown systems are structured in a single cluster or multiple clusters. The new algorithm divides the tap-weight vector into groups of equal-sized sub-vectors and then introduces a mixed -norm constraint on the filter tap-weight vector in addition to the original mean-square-error cost function. The parameter p in the constraint takes any value between zero and two, thus improving the identification performance of the block-sparse systems. The effect of the parameter p and the group size on the performance of the proposed algorithm is studied, and general guidelines for choosing these two parameters are provided to facilitate practical use. The advantage of the proposed scheme is that no comparison operations are required while algebraic operations are of the same order as the block-sparse lms algorithm. Numerical simulations show that the proposed norm-based block-sparsity-aware algorithms and single-norm penalized lms strategies.
In this paper, we propose a new digital blind inphase/quadrature-phase (I/Q) mismatch compensation technique for image rejection in a direct-conversion receiver (DCR). The proposed image-rejection circuit adopts DC of...
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In this paper, we propose a new digital blind inphase/quadrature-phase (I/Q) mismatch compensation technique for image rejection in a direct-conversion receiver (DCR). The proposed image-rejection circuit adopts DC offset cancellation and a sign-sign least mean squares (lms) algorithm with a unique step size adaptation both for a fast and precise I/Q mismatch estimation. In addition, several performance-optimizing design considerations related to accuracy, speed, and hardware simplicity are discussed. The implementation of the proposed circuit in an FPGA results in an image-rejection ratio (IRR) of 65 dB, which is the best performance with modulated signals, along with an adaptation time of 0.9 seconds, which is a tenfold increase in the compensation speed as compared to previously reported circuits. The proposed technique will be a promising solution in the area of image rejection to increase both the speed and accuracy of future DCRs.
Adaptive filtering acquisition method has been proved to be an effective pseudo-noise (PN) code acquisition method in DS-SS system, which is especially useful for long PN code acquisition in low Signal to Noise Ratio ...
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Adaptive filtering acquisition method has been proved to be an effective pseudo-noise (PN) code acquisition method in DS-SS system, which is especially useful for long PN code acquisition in low Signal to Noise Ratio (SNR) environment. In order to make use of this method in those PN code acquisition systems with data modulation, a modified adaptive filtering is proposed in this paper, where the effect of polarity reversion caused by data modulation on PN code is removed by employing absolutely successive difference technique in both the received signals and local generated PN code. Compared with the adaptive filtering acquisition method, even with data modulation, the proposed method can attain almost similar acquisition performance, which is tested by simulations.
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