Topic
Time–frequency analysis
About: Time–frequency analysis is a research topic. Over the lifetime, 5407 publications have been published within this topic receiving 104346 citations.
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TL;DR: In this article, the authors consider orthonormal bases of open face RNconsisting of discretized rescaled Walsh functions, where the Walsh group is replaced by other finite abelian groups.
44 citations
TL;DR: Wavelet-based detection method shows better sensitivity than spectral and time-domain methods and effectiveness of the localization method in presence of complex power supply network, measurement noise, and process variation is addressed.
Abstract: Transient current (IDD) testing has been often cited and investigated as an alternative and/or supplement to quiescent current (IDDQ) testing. In this correspondence, we present a novel integrated method for fault detection and localization using wavelet transform-based IDD waveform analysis. The time-frequency resolution property of wavelet transform helps us detect as well as localize faults in digital CMOS circuits. Experiments performed on measured data from a fabricated 8-bit shift register, and simulation data from more complex circuits show promising results for both detection and localization. Wavelet-based detection method shows better sensitivity than spectral and time-domain methods. Effectiveness of the localization method in presence of complex power supply network, measurement noise, and process variation is also addressed.
44 citations
TL;DR: In this article, the authors show that there exist fast constructions for computing approximate projections onto the leading Slepian basis elements of the discrete Prolate Spheroidal Sequence (DPSS).
44 citations
TL;DR: The dilating Gabor transformation is introduced by using a changeable window of Gaussian function in a conventional Gabor transform to analyze the optical fringes of 3-D shape measurement, providing more accurate results than Fourier transform and Gabortransform.
Abstract: In order to overcome the limitations of conventional Fourier transform and Gabor transform analyzing nonstationary signals, dilating Gabor transform is applied to analyze the optical fringes of 3-D shape measurement. The dilating Gabor transformation is introduced by using a changeable window of Gaussian function in a conventional Gabor transform. This phase analysis method provides more accurate results than Fourier transform and Gabor transform. Simulation and experimental results are presented that demonstrate the validity of the principle.
44 citations
TL;DR: A wide-area frequency monitoring network (FNET) is introduced as the reference frequency database and statistical features of frequency of the four North American interconnections in terms of different time scales are analyzed.
Abstract: Frequency is an important parameter for the operation and control of power systems. One novel application of frequency measurements involves using this information to authenticate a digital audio/video recording presented as forensic evidence in legal proceedings. To apply this technique, called the electrical network frequency (ENF) criterion, both a reference frequency database and an accurate frequency estimation method are required. This paper briefly introduces a wide-area frequency monitoring network (FNET) as the reference frequency database and analyzes statistical features of frequency of the four North American interconnections in terms of different time scales. Combined with digital filtering and a three-sample interpolation, the short-time Fourier transform (STFT) is adjusted to estimate the ENF embedded in digital audio recordings. A procedure of using the ENF criterion, ranging from signal preprocessing to ENF estimation and reference frequency database matching, is then proposed. Further, oscillator error of the digital recording device is considered and an iterative error correction method is given to assist with the frequency database matching. Factors which influence the accuracy of frequency estimation, such as parameter selections of the STFT and signal-to-noise ratio, are also discussed. Test results show that the procedure is capable of performing digital audio authentication.
44 citations