Open Access

A Window Width Optimized S-Transform

EURASIP Journal on Advances in Signal Processing20072008:672941

Received: 14 May 2007

Accepted: 15 November 2007

Published: 4 December 2007


Energy concentration of the S-transform in the time-frequency domain has been addressed in this paper by optimizing the width of the window function used. A new scheme is developed and referred to as a window width optimized S-transform. Two optimization schemes have been proposed, one for a constant window width, the other for time-varying window width. The former is intended for signals with constant or slowly varying frequencies, while the latter can deal with signals with fast changing frequency components. The proposed scheme has been evaluated using a set of test signals. The results have indicated that the new scheme can provide much improved energy concentration in the time-frequency domain in comparison with the standard S-transform. It is also shown using the test signals that the proposed scheme can lead to higher energy concentration in comparison with other standard linear techniques, such as short-time Fourier transform and its adaptive forms. Finally, the method has been demonstrated on engine knock signal analysis to show its effectiveness.


Optimization SchemeTest SignalQuantum InformationFrequency ComponentEnergy Concentration

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Authors’ Affiliations

Department of Electrical and Computer Engineering, The University of Western Ontario, London, Canada
Electrical Engineering Department, University of Montenegro, Podgorica, Serbia and Montenegro


© Ervin Sejdić et al. 2008

This article is published under license to BioMed Central Ltd. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.