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Desired Signal (desired + signal)

Distribution by Scientific Domains

Engineering	100%

Distribution within Engineering

Control Systems Technology	60%
Communication Technology	40%

Selected Abstracts

The application of modified lapped transform domain median filter to narrow,band interference excision in DSSS systems

EUROPEAN TRANSACTIONS ON TELECOMMUNICATIONS, Issue 4 2001
Chongni Li Guangruihu
A novel communication receiver which uses lapped transform (LT) incorporating modified median filter (MMF) algorithm is designed for narrow,band interference (NB1) excision. Comparing to traditional Fourier Transform, LT has longer basis vectors, less spectral leakage, thus better frequency resolution. The LT domain MMF algorithm takes full advantages of the direct sequence spread spectrum signal, as well as the characteristics of LT, performs the transform domain filtering twice. The first filtering locates the position of interference and mitigates most of them. The second filtering was performed in a small neighborhood of the located interference. So LT domain MMF algorithm can completely mitigate the interference without distorting the desired signal. Simulation results demonstrated the improved BER performance and increased robustness of our approach. [source]

Blind decoder-assisted interference reduction for coded DS-CDMA systems,

INTERNATIONAL JOURNAL OF ADAPTIVE CONTROL AND SIGNAL PROCESSING, Issue 9 2005
Ryan A. Pacheco
Abstract We propose an iterative blind interference reduction strategy for short-burst coded DS-CDMA systems. The blind strategy works by creating a set of ,training sequences' in the receiver that are used as input to an interference reduction algorithm whose task is to produce a corresponding set of equalizers that attempt to recover the desired signal. To maintain a reasonable complexity level we develop a semi-blind interference reduction algorithm that is capable of equalizing the received signal with a relatively small training sequence length (thus maintaining a small training sequence set). The objective then becomes to determine which equalizer from the generated set gives the best performance (smallest bit error). It is demonstrated that the success of this scheme depends greatly on the ability to find an appropriate criterion for picking the best equalizer. Of the tested criteria, one based on feedback from the decoder (essentially using trellis information) is shown to achieve nearly optimal performance. Copyright © 2005 John Wiley & Sons, Ltd. [source]

Kalman filter-based adaptive control for networked systems with unknown parameters and randomly missing outputs

INTERNATIONAL JOURNAL OF ROBUST AND NONLINEAR CONTROL, Issue 18 2009
Y. Shi
Abstract This paper investigates the problem of adaptive control for networked control systems with unknown model parameters and randomly missing outputs. In particular, for a system with the autoregressive model with exogenous input placed in a network environment, the randomly missing output feature is modeled as a Bernoulli process. Then, an output estimator is designed to online estimate the missing output measurements, and further a Kalman filter-based method is proposed for parameter estimation. Based on the estimated output and the available output, and the estimated model parameters, an adaptive control is designed to make the output track the desired signal. Convergence properties of the proposed algorithms are analyzed in detail. Simulation examples illustrate the effectiveness of the proposed method. Copyright © 2008 John Wiley & Sons, Ltd. [source]

A 80,100 GHz image-reject passive-HEMT mixer

MICROWAVE AND OPTICAL TECHNOLOGY LETTERS, Issue 12 2006
John W. Archer
Abstract This paper describes a single-sideband, subharmonically pumped, passive-HEMT integrated circuit mixer developed for use in transceivers for point-to-point telecommunications in the 83,87 GHz band. The gallium arsenide (GaAs) monolithic microwave integrated circuit (MMIC) can readily be fabricated using a standard commercial process. The mixer performs equally well for either up- or down- conversion. For RF signals in the range 80,100 GHz, the conversion loss is typically 20 dB with LO drive in the range 40,50 GHz. Under these conditions, high rejection of the undesired sideband (>18 dB), relative to the desired signal, is achieved. For up-conversion, 1 dB compression of the mixer gain typically occurs at ,12 dBm RF output power. © 2006 Wiley Periodicals, Inc. Microwave Opt Technol Lett 48: 2429,2433, 2006; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.21953 [source]

A feedforward,feedback controller for infinite-dimensional systems and regulation of bounded uniformly continuous signals

INTERNATIONAL JOURNAL OF ROBUST AND NONLINEAR CONTROL, Issue 5 2006
Eero Immonen
Abstract We design a controller for infinite-dimensional linear systems (with bounded control, observation and feedthrough operators) which, under certain assumptions, achieves asymptotic tracking of arbitrary bounded uniformly continuous reference signals in the presence of disturbances. The proposed controller is of feedforward,feedback type: The dynamic feedback part is used to stabilize the closed-loop system consisting of the plant and the controller, whereas the feedforward part is tuned using the regulator equations to achieve the regulation of desired signals. We also completely solve the regulator equations for SISO systems, and we discuss robustness properties of the proposed controller. A useful feature in our design is that the feedforward part of the controller can be designed independently of the feedback part. This automatically leads to a degree of robustness in the stabilizing part of the controller, which is not present in the existing state feedback controllers solving the same output regulation problem. Copyright © 2006 John Wiley & Sons, Ltd. [source]