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On the design of sinc interpolator for pilot symbol assisted modulation systems

IEEE TRANSACTIONS ON WIRELESS COMMUNICATIONS 2006年第9期5卷 2578-2585页

作者： Xiao, Lei Dong, Xiaodai Soong, Anthony C. K. Univ Notre Dame Dept Elect Engn Notre Dame IN 46556 USA Univ Victoria Dept Elect & Comp Engn Victoria BC V8W 3P6 Canada Huawei Technol Co Ltd Plano TX 75075 USA

This paper investigates the design of practical sinc interpolation filters in pilot symbol assisted modulation (PSAM) systems. By closely examining the error mechanism in PSAM channel estimation, we show that the error floor phenomenon is caused by the non-ideal characteristic of the interpolation filter. Based on the use of adjustable window functions, we present a set of design guidelines to determine the shape of window functions, the window/filter length and the pilot insertion rate. The design choices essentially reflect the trade-offs between error performance, implementation complexity and transmission rate.

关键词： pilot symbol assisted modulation (PSAM) channel estimation interpolator design window functions quadrature amplitude modulation (QAM) symbol error rate (SER) fading channels

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Discrete-time windows with minimal RMS bandwidth for given RMS temporal width

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SIGNAL PROCESSING 2014年 102卷 240-246页

作者： Starosielec, Sebastian Haegele, Daniel Ruhr Univ Bochum Arbeitsgrp Spektroskopie Kondensierten Mat D-44780 Bochum Germany

We derive a family of discrete window functions for the N-point Fourier transform for application in spectral analysis that optimize the root mean square (RMS) frequency width sigma(omega) for a given temporal RMS width sigma(t). The window family yields as a byproduct the minimum time-bandwidth product sigma(omega)sigma(t) for given sigma(t) and N. The new windows interpolate for decreasing sigma(t) between the popular Cosine-window and a nearly Gaussian window. The new "confined Gaussian" window function g(k)((cG)) (with k=0,...,N-1) is extremely well approximated by g(k)((acG)) proportional to G(k)-G(-1/2)[G(k+N)+G(k-N)]/[G(-1/2+N)+G(-1/2-N)] with the Gaussian G(x) = exp[delta t(2)(x-(N-1)/2)(2)/(4s(2))], the temporal width s approximate to sigma(t), and time step delta t. (C) 2014 Elsevier B.V. All rights reserved.

关键词： window functions Uncertainty principle Time-bandwidth product N-point Fourier transform

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Introduction of multiple nulls in otherwise omnidirectional pattern of circular dipole array

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ELECTRONICS LETTERS 1998年第14期34卷 1371-1373页

作者： Abele, J Joubert, J Odendaal, JW Univ Karlsruhe Inst Hochfrequenztech & Elekt D-76128 Karlsruhe Germany Univ Pretoria Dept Elect & Elect Engn ZA-0002 Pretoria South Africa

The results are presented of a synthesis procedure for omnidirectional radiation patterns with multiple nulls for circular arrays of vertical dipoles. The gain ripple in the omnidirectional region can be controlled by the use of window functions in the design procedure. The results are verified using the numerical electromagnetics code.

关键词： numerical electromagnetics code design procedure dipole antenna arrays vertical dipoles Antenna theory antenna radiation patterns circular dipole array window functions gain ripple Antenna arrays synthesis procedure omnidirectional pattern multiple nulls

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Development of Accurate Model for Memristor-Based Filters and Oscillators: Amplitude, Frequency and Ramp-Rate Dependent Analysis

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IEEE TRANSACTIONS ON CIRCUITS AND SYSTEMS II-EXPRESS BRIEFS 2024年第2期71卷 872-876页

作者： Sowmya, Rami Reddy Sumanth, Arige Kailath, Binsu J. Dixit, Tejendra Indian Inst Informat Technol Design & Mfg Kancheep ECE Dept Optoelect & Quantum Devices Grp Chennai 600127 India Indian Inst Informat Technol Design & Mfg Kancheep Dept Elect & Commun Engn VLSI Design Lab Chennai 600127 India

The utilization of memristors in analog circuits has been significantly enhanced through the development of various models, namely linear-ion drift, non-linear-ion drift, Simmons tunnel barrier, ThrEshold Adaptive Memristor, and Voltage ThrEshold Adaptive Memristor (VTEAM) models. These models have been instrumental in improving the effectiveness and functionality of memristors in analog circuit applications. The utilization of Joglekar, Biolek, Prodromakis, and Kvatinsky window functions has been employed to investigate the ideal behavior of memristors. In order to facilitate the advancement of analog circuits employing memristors;it is imperative that proposed models must exhibit certain essential characteristics, including amplitude-dependent, frequency-dependent, and ramp-rate dependent behavior. The applicability of the VTEAM model in conjunction with the Biolek window function for describing amplitude variation, as well as the Prodromakis model for describing ramp-rate dependent behavior, is demonstrated in this brief. In addition, we have provided analysis on the choice of circuitry for window functions in combination with VTEAM models. We specifically investigated the design of analog filters with low-pass and high-pass characteristics, and have found that the utilization of the Joglekar window function and Prodromakis window function yields superior filter performance, respectively. Subsequently, an op-amp based phase-shift oscillator was designed with the proposed memristor model.

关键词： Memristors Mathematical models Behavioral sciences Biological system modeling Threshold voltage Oscillators Integrated circuit modeling Resistance switching memristor models VTEAM state variable window functions ramp-rate

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On the Equivalence of Hanning-Weighted and Overlapped Analysis windows Using Different window Sizes

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IEEE SIGNAL PROCESSING LETTERS 2012年第1期19卷 27-30页

作者： Baggenstoss, Paul M. USN Undersea Warfare Ctr Newport RI 02841 USA

This letter is concerned with time-series analysis using overlapped processing windows shaded using the Hanning window function, such as is used in short-time Fourier transform (STFT) analysis. We present a special case where different analysis window sizes produce equivalent outputs where equivalence is defined by the existence of an orthonormal linear transformation relating the two analyses. We apply the concept to the problem of detecting pulses of unknown duration in Gaussian noise. We also demonstrate how the method can be used to apply the PDF projection theorem to shaded overlapped processing windows.

关键词： Parameter estimation pulse-length estimation time series analysis window functions

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Tuning of FIR filter transition bandwidth using fractional Fourier transform

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SIGNAL PROCESSING 2007年第12期87卷 3147-3154页

作者： Sharma, S. N. Saxena, Rajiv Saxena, S. C. Samrat Ashok Technol Inst Vidisha 464001 India Jay Pee Inst Engn & Technol JIET Raghogarh 473226 Guna India Indian Inst Technol Roorkee 247007 Uttar Pradesh India

The transition bandwidth of window-based FIR filters is proportional to the window main-lobe width, which in turn is proportional to the length of the window function. As such, transition bandwidth of FIR filters can be directly tuned by varying window length for on-line tuning applications. However, analysis of window functions in fractional Fourier domain, a generalization of Fourier domain, also establishes the dependence of window main-lobe width on the order of fractional Fourier transform (FRFT). Thus, an alternative methodology to tune the transition bandwidth, based on FRFT, is developed in this work. The proposed methodology is useful for frequency domain filtering and introduces a comparative ease in tuning by eliminating the need to re-compute the impulse response coefficients. Also, significant computational saving has been achieved using FRFT. However, it is observed that the direct approach can introduce a lot more adjustability in the transition bandwidth than the FRFT approach. Apart from Kaiser window, considered to be optimum for FIR filter design, another window with a high side-lobe fall-off-rate (SLFOR), viz, Parzen-cos(6) (pi t) (PC6), has also been used in the proposed on-line filter tuning. Better performance of windows with high SLFOR in on-line sharpening is illustrated with the aid of simulation results. (C) 2007 Elsevier B.V. All rights reserved.

关键词： window functions FIR filter fractional Fourier transform (FRET, DFRFT)

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An analysis of NMR sensitivity enhancements obtained using non-uniform weighted sampling, and the application to protein NMR

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JOURNAL OF MAGNETIC RESONANCE 2012年 219卷 46-52页

作者： Waudby, Christopher A. Christodoulou, John UCL Inst Struct & Mol Biol London WC1E 6BT England Univ London Birkbeck Coll London WC1E 6BT England

Non-uniform weighted sampling (NUWS) is a sampling strategy, related to non-uniform sampling (NUS) in the limit of long acquisition times, in which each indirect increment of a multidimensional spectrum is sampled multiple times according to some weighting function. As the spectrum is fully sampled it can be processed in a conventional manner by the discrete Fourier transform, making the analysis of sensitivity much more straightforward than for NUS data. Previously, 2-3 fold increases in signal-to-noise ratio (SNR) have been reported using NUWS. However, as the sampling schedule acts as a window function, the observed SNR must be compared with uniformly sampled data apodized using the same weighting function. On doing this, we calculate more modest improvements of 10-20% in SNR, and these are verified experimentally for spectra of a-synuclein and YFP. Nevertheless, we prove that NUWS always improves the sensitivity compared with identically processed uniformly sampled data, and when combined with rapid recycling experiments such as the SOFAST-HMQC, NUWS methods have the potential to make a useful and practical contribution to sensitivity-limited measurements. (C) 2012 Elsevier Inc. All rights reserved.

关键词： Non-uniform sampling Sensitivity Apodization window functions

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Design of nonrecursive digital filters using the ultraspherical window function

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EURASIP JOURNAL ON APPLIED SIGNAL PROCESSING 2005年第12期2005卷 1910-1922页

作者： Bergen, SWA Antoniou, A Univ Victoria Dept Elect & Comp Engn Victoria BC V8W 3P6 Canada

An efficient method for the design of nonrecursive digital filters using the ultraspherical window function is proposed. Economies in computation are achieved in two ways. First, through an efficient formulation of the window coefficients, the amount of computation required is reduced to a small fraction of that required by standard methods. Second, the filter length and the independent window parameters that would be required to achieve prescribed specifications in lowpass, highpass, bandpass, and bandstop filters as well as in digital differentiators and Hilbert transformers are efficiently determined through empirical formulas. Experimental results demonstrate that in many cases the ultraspherical window yields a lower-order filter relative to designs obtained using windows like the Kaiser, Dolph-Chebyshev, and Saramdki windows. Alternatively, for a fixed filter length, the ultraspherical window yields reduced passband ripple and increased stopband attenuation relative to those produced when using the alternative windows.

关键词： nonrecursive digital filters FIR filters window functions ultraspherical window digital differentiators Hilbert transformers

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KAISER-HAMMING window AND ITS PERFORMANCE ANALYSIS FOR NONRECURSIVE DIGITAL FILTER DESIGN

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JOURNAL OF THE FACULTY OF ENGINEERING AND ARCHITECTURE OF GAZI UNIVERSITY 2014年第4期29卷 823-833页

作者： Avci, Kemal Abant Izzet Baysal Univ Elekt & Elekt Muhendisligi Bolumu Bolu Turkey

In this paper, a new window function is proposed for the design of nonrecursive digital filters which have area of usage in many applications of electronics engineering. As the name implies, this window is obtained by the combination of two different windows in literature, known as Kaiser and Hamming. The proposed window is first analyzed in terms of ripple ratio and mainlobe width, which are known as window spectral parameters. Moreover, window spectral comparisons of the proposed window with Kaiser and Hamming windows are performed. The window simulation results show that the proposed window can provide better ripple ratio for fixed window length and mainlobe width. Secondly, the analysis of the proposed window in nonrecursive digital filter design is performed in terms of minimum stopband attenuation and transition width, which are known as filter spectral parameters, and also its comparisons with Kaiser, Cosh, Exponential, and Hamming windows are given. Filter comparison results show that the filters designed by the proposed window can provide better minimum stopband attenuation than the ones designed by the others for fixed filter length and transition band width. That is, it is concluded that with the proposed window a better filter performance can be exhibited. This conclusion is supported by demonstrating better filtering of a noise in an audio signal with the proposed window.

关键词： Nonrecursive digital filters window functions Kaiser-Hamming window Kaiser window Hamming window

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θ-Constrained multi-dimensional aggregation

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INFORMATION SYSTEMS 2011年第2期36卷 341-358页

作者： Akinde, Michael Boehlen, Michael H. Chatziantoniou, Damianos Gamper, Johann Free Univ Bolzano Bozen Fac Comp Sci I-39100 Bolzano Italy Univ Zurich Dept Comp Sci CH-8006 Zurich Switzerland Athens Univ Econ & Business Fac Management Sci & Technol Athens Greece

The SQL:2003 standard introduced window functions to enhance the analytical processing capabilities of SQL. The key concept of window functions is to sort the input relation and to compute the aggregate results during a scan of the sorted relation. For multi-dimensional OLAP queries with aggregation groups defined by a general theta condition an appropriate ordering does not exist, though, and hence expensive join-based solutions are required. In this paper we introduce theta-constrained multi-dimensional aggregation (theta-MDA), which supports multi-dimensional OLAP queries with aggregation groups defined by inequalities. theta-MDA is not based on an ordering of the data relation. Instead, the tuples that shall be considered for computing an aggregate value can be determined by a general theta condition. This facilitates the formulation of complex queries, such as multi-dimensional cumulative aggregates, which are difficult to express in SQL because no appropriate ordering exists. We present algebraic transformation rules that demonstrate how the theta-MDA interacts with other operators of a multi-set algebra. Various techniques for achieving an efficient evaluation of the theta-MDA are investigated, and we integrate them into concrete evaluation algorithms and provide cost formulas. An empirical evaluation with data from the TPC-H benchmark confirms the scalability of the theta-MDA operator and shows performance improvements of up to one order of magnitude over equivalent SQL implementations. (C) 2010 Elsevier B.V. All rights reserved.

关键词： OLAP SQL/OLAP window functions Multi-dimensional aggregation

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