نتایج جستجو برای: time frequency transform

تعداد نتایج: 2342512  

M. Dorostgan M. M. Naghshiii * M. Modarres-Hashemi

Nowadays, Radar systems have many applications and radar imaging is one of the most important of these applications. Inverse Synthetic Aperture Radar (ISAR) is used to form an image from moving targets. Conventional methods use Fourier transform to retrieve Doppler information. However, because of maneuvering of the target, the Doppler spectrum becomes time-varying and the image is blurred. Joi...

K-complex is an underlying pattern in the sleep EEG. Due to the role of sleep studies inneurophysiologic and cognitive disorders diagnosis, reliable methods for analysis and detection of this patternare of great importance. In our previous work, Synchrosqueezing Transform (SST) was proposed for analysisof this pattern. SST is an EMD-like tool, which benefits from wavelet transform and reallocat...

پایان نامه :وزارت علوم، تحقیقات و فناوری - دانشگاه شیراز - دانشکده برق و کامپیوتر 1392

در این پایان نامه دسته بندی سیگنال های مغزی به منظور تشخیص بیماری صرع با بهره گرفتن از ویژگی های زمان-فرکانس انجام شده است. صفحات زمان-فرکانس همزمان اطلاعات فرکانس و زمانی را در بر دارند و از این رو نسبت به پردازش های صرفاً زمانی و یا صرفاً فرکانسی دارای امتیازاتی هستند، هر چند که از ایراداتی مانند مولفه های مزاحم ویا اصل عدم قطعیت هایزنبرگ رنج می برند. این پایان نامه چند صفحه ی زمان-فرکانس را م...

2011
Sitanshu Sekhar Sahu Ganapati Panda

Accurate identification of protein-coding regions (exons) in DNA sequences has been a challenging task in bioinformatics. Particularly the coding regions have a 3-base periodicity, which forms the basis of all exon identification methods. Many signal processing tools and techniques have been applied successfully for the identification task but still improvement in this direction is needed. In t...

2008
Jonathan M. Lilly

Properties determining optimal behavior of continuous analytic wavelet functions are investigated, and wavelet functions nearly obtaining such behavior are identified. This is accomplished through detailed investigation of the generalized Morse wavelets, a highly flexible family of exactly analytic continuous wavelets. The degree of time/frequency localization, the existence of a unique interpr...

2009
Douglas L. Jones

The discrete Fourier transform (DFT) maps a nite number of discrete time-domain samples to the same number of discrete Fourier-domain samples. Being practical to compute, it is the primary transform applied to real-world sampled data in digital signal processing. The DFT has special relationships with the discrete-time Fourier transform and the continuous-time Fourier transform that let it be u...

2003
Karen L. Butler-Purry Mustafa Bagriyanik

This paper presents the time domain and timefrequency domain analysis results of incipient events in single-phase distribution transformers. This analysis will aid in the development of an automatic detection method for internal incipient faults in the transformers. The detection method can provide information to predict failures ahead of time so that the necessary corrective actions are taken ...

2017
Divya Choudhary

This article presents the use of the synchrosqueezing transform (SST) for the timefrequency analysis of shock and vibration measurements. The time-frequency resolution properties of SST is demonstrated by analyzing acceleration measurements from pallets dropped from heights and vibration of pallets acquired in controlled laboratory settings. The article presents results that indicate that SST, ...

2004
ÁRPÁD BÉNYI LOUKAS GRAFAKOS KARLHEINZ GRÖCHENIG K. Okoudjou

We prove the boundedness of a general class of Fourier multipliers, in particular of the Hilbert transform, on modulation spaces. In general, however, the Fourier multipliers in this class fail to be bounded on L spaces. The main tools are Gabor frames and methods from time-frequency analysis.

Journal: :Digital Signal Processing 2007
Robert Glenn Stockwell

The S-transform is a time-frequency representation known for its local spectral phase properties. A key feature of the S-transform is that it uniquely combines a frequency dependent resolution of the time-frequency space and absolutely referenced local phase information. This allows one to define the meaning of phase in a local spectrum setting, and results in many desirable characteristics. On...

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