Dissertations / Theses on the topic 'Short-time Fourier transform'
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Okamura, Shuhei. "The Short Time Fourier Transform and Local Signals." Research Showcase @ CMU, 2011. http://repository.cmu.edu/dissertations/58.
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In this thesis, I examine the theoretical properties of the short time discrete Fourier transform (STFT). The STFT is obtained by applying the Fourier transform by a fixed-sized, moving window to input series. We move the window by one time point at a time, so we have overlapping windows. I present several theoretical properties of the STFT, applied to various types of complex-valued, univariate time series inputs, and their outputs in closed forms. In particular, just like the discrete Fourier transform, the STFT’s modulus time series takes large positive values when the input is a periodic signal. One main point is that a white noise time series input results in the STFT output being a complex-valued stationary time series and we can derive the time and time-frequency dependency structure such as the cross- covariance functions. Our primary focus is the detection of local periodic signals. I present a method to detect local signals by computing the probability that the squared modulus STFT time series has consecutive large values exceeding some threshold after one exceeding observation following one observation less than the threshold. We discuss a method to reduce the computation of such probabilities by the Box-Cox transformation and the delta method, and show that it works well in comparison to the Monte Carlo simulation method.
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Hon, Tsz Kin. "Time-frequency analysis and filtering based on the short-time Fourier transform." Thesis, King's College London (University of London), 2013. https://kclpure.kcl.ac.uk/portal/en/theses/timefrequency-analysis-and-filtering-based-on-the-shorttime-fourier-transform(de8bcca8-cd9d-42a3-bf79-281672478744).html.
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The joint time-frequency (TF) domain provides a convenient platform for signal analysis by involving the dimension of time in the frequency representation of a signal. A straightforward way to acquire localized knowledge about the frequency content of the signal at different times is to perform the Fourier transform over short-time intervals rather than processing the whole signal at once. The resulting TF representation is the short-time Fourier transform (STFT), which remains to date the most widely used method for the analysis of signals whose spectral content varies with time. Recent application examples of the STFT and its variants – e.g. the squared magnitude of the STFT known as the spectrogram – include signal denoising, instantaneous frequency estimation, and speech recognition. In this thesis, we first address the main limitation of the trade-off between time and frequency resolution for the TF analysis by proposing a novel adaptation procedure which properly adjusts the size of the analysis window over time. Our proposed approach achieves a high resolution TF representation, and can compare favorably with alternative time-adaptive spectrograms as well as with advanced quadratic representations. Second, we propose a new scheme for the time-frequency adaptation of the STFT in order to automatically determine the size and the phase of the analysis window at each time and frequency instant. This way, we can further improve the resolution of the conventional as well as the time-adaptive spectrograms. Finally, we focus on denoising non-stationary signals in the STFT domain. We introduced an optimized TF mask in the STFT domain, which is based on the concept of the multi-window spectrogram. Experimentation has shown that the introduced approach can effectively recover distorted signals based on a small set of representative examples of the noisy observation and the desired signal.
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Sun, Pu. "Comparison of STFT and Wavelet Transform inTime-frequency Analysis." Thesis, Högskolan i Gävle, Avdelningen för elektronik, matematik och naturvetenskap, 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:hig:diva-19072.
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The wavelet transform technique has been frequently used in time-frequency analysis as a relatively new concept. Compared to the traditional technique Short-time Fourier Transform (STFT), which is theoretically based on the Fourier transform, the wavelet transform has its advantage on better locality in time and frequency domain, but not significant as the solutions in spectrum. Wavelet transform has dynamic ‘window functions’ to represent time-frequency positions of raw signals, and can get better resolutions in time-frequency analysis. In this report, we shall first briefly introduce fuzzy sets and related concepts. And then we will evaluate their similarities and differences by not only the theoretic comparisons between STFT and wavelet transform, but also the process of the de-nosing to a noisy recorded signal.
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Fredriksson, Henrik. "On the Short-Time Fourier Transform and Gabor Frames generated by B-splines." Thesis, Linnéuniversitetet, Institutionen för datavetenskap, fysik och matematik, DFM, 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:lnu:diva-20262.
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In this thesis we study the short-time Fourier transform. The short-time Fourier transform of a function f(x) is obtained by restricting our function to a short time segment and take the Fourier transform of this restriction. This method gives information locally of f in both time and frequency simultaneously.To get a smooth frequency localization one wants to use a smooth window, whichmeans that the windows will overlap. The continuous short-time Fourier transform is not appropriate for practical purpose, therefore we want a discrete representation of f. Using Gabor theory, we can write a function f as a linear combination of time- and frequency shifts of a fixed window function g with integer parameters a; b > 0. We show that if the window function g has compact support, then g generates a Gabor frame G(g; a; b). We also show that for such a g there exists a dual frame such that both G(g; a; b) and its dual frame has compact support and decay fast in the Fourier domain. Based on [2], we show that B-splines generates a pair of Gabor frames.
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MacIsaac, Dawn. "Using the short-time Fourier transform to assess localized fatigue in dynamic muscle contractions." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1999. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape8/PQDD_0007/MQ46265.pdf.
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Schippa, Robert [Verfasser]. "Short-time Fourier transform restriction phenomena and applications to nonlinear dispersive equations / Robert Schippa." Bielefeld : Universitätsbibliothek Bielefeld, 2019. http://d-nb.info/1200097637/34.
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E, Okwelume Gozie, and Ezeude Anayo Kingsley. "BLIND SOURCE SEPARATION USING FREQUENCY DOMAIN INDEPENDENT COMPONENT ANALYSIS." Thesis, Blekinge Tekniska Högskola, Avdelningen för signalbehandling, 2007. http://urn.kb.se/resolve?urn=urn:nbn:se:bth-1312.
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Our thesis work focuses on Frequency-domain Blind Source Separation (BSS) in which the received mixed signals are converted into the frequency domain and Independent Component Analysis (ICA) is applied to instantaneous mixtures at each frequency bin. Computational complexity is also reduced by using this method. We also investigate the famous problem associated with Frequency-Domain Blind Source Separation using ICA referred to as the Permutation and Scaling ambiguities, using methods proposed by some researchers. This is our main target in this project; to solve the permutation and scaling ambiguities in real time applicationsGozie: modebelu2001@yahoo.com Anayo: ezeudea@yahoo.com
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Albertini, Alessandro. "Influenza dei parametri della Short-Time Fourier Transform nell’analisi di emissioni condotte nell’intervallo 2-150 kHz." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2019.
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Il lavoro di tesi si basa sull'implementazione di un algoritmo in LabVIEW per il calcolo della STFT su segnali in un intervallo di frequenze tra 2 e 150 kHz. Per questo intervallo di frequenza non esistono ancora norme che indichino come effettuare le misure e i limiti massimi di emissione per quanto riguarda la compatibilità elettromagnetica delle apparecchiature.
Per testare l'algoritmo si è costruito l'andamento in frequenza di un segnale deducendolo d a uno spettro in frequenza noto, da questosi è poi calcolato l'andamento del segnale nel dominio del tempo attraverso una IDFT con software Matlab.
Il segnale così generato è stato fatto replicare da un generatore di segnale arbitrario ed è stato poi acquisito attraverso un oscilloscopio comandato dall'algoritmo in LabVIEW.
Una volta acquisito il segnale ne è stata calcolata la STFT, che calcola lo spettro in frequenza del segnale acquisito, attraverso la suddivisione del time record in finestre temporali più piccole e soprattutto ben definite (time segment).
Sono state efffettuate numerose prove utilizzando 19 finestre diverse, su diversi time segment e diversi overlap.
I campioni dello spettro, poi, sono stati trasferiti a Matlab, dove è stato implementato un terzo codice per il post-processing.
Ovvero, sono stati costruiti dei box plot in funzione della finestra usata, del time segment e dell'overlap.
Infine, sono stati messi a confronto i risultati ottenuti in funzione delle finestre utilizzate e dall'ampiezza temporale delle finestre, e mettendo in risalto i risultati ottenuti affetti o meno dallo short range leakage.
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Paneras, Demetrios E. "Efficient STFT analysis over limited frequency regions." Thesis, Boston University, 1992. https://hdl.handle.net/2144/34651.
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Thesis (M.S.)--Boston UniversityPLEASE NOTE: Boston University Libraries did not receive an Authorization To Manage form for this thesis or dissertation. It is therefore not openly accessible, though it may be available by request. If you are the author or principal advisor of this work and would like to request open access for it, please contact us at open-help@bu.edu. Thank you.
We address the problem of efficiently computing, over narrow frequency bands, the short-time Fourier transform (STFT) and approximations to the STFT. This problem is important for the design of signal understanding systems that have to efficiently carry out STFT reprocessing of signals in order to examine detailed features of signal components that have already been located within narrow frequency bands. In the computation of the exact STFT we use an "overlap pruning" approach (Covell et al. 1992) for exploiting the commonality of computations between successive slices of the STFT with unity decimation interval. We have also extended this approach to the STFT with non-unity decimation intervals and combined it with a frequency pruning method (Sreenivas et al. 1980) to provide additional computational savings. In the computation of approximations to the STFT we use an algorithm (Khan et al. 1988) for efficiently computing Taylor series approximations over narrow frequency bands. Through examples involving real data we demonstrate the feasibility of using the approximated STFT to obtain more accurate estimates of the center frequency of spectral peaks, and to resolve multiple peaks that have been smeared due to the use of short window lengths. The efficiency of all the algorithms we have investigated is less than 0(N log N) multiplications per STFT slice and can be as small as O(N) multiplications per STFT slice in certain cases. Consequently, all the algorithms compare favourably with the standard FFT implementation of the STFT which requires O(N log N) multiplications per slice. All the algorithms considered in this thesis were implemented in software and tested on synthetic and real sound signals.
2031-01-01
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Wojcicki, Kamil Krzysztof. "Role of the Short-Time Phase Spectrum in Speech Processing." Thesis, Griffith University, 2011. http://hdl.handle.net/10072/366376.
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Majority of speech processing algorithms that employ the short-time Fourier transform process the short-time magnitude spectrum, while either discarding the short-time phase spectrum or leaving it unchanged. This is in-part due to a long-standing belief among speech researchers that the short-time phase spectrum, computed over small analysis window durations of 20–40 ms, contains little useful information and is thus (mostly) unimportant for speech processing (though it is accepted that the phase spectrum does contribute to some extent to naturalness and quality aspects of speech). The above belief has been supported by numerous studies presented in the literature. Results of recent speech perception experiments suggest, however, that the phase spectrum (at small analysis window durations of 20–40 ms) does contain significant amount of useful information, provided that the analysis window function is carefully selected. It was reported that the use of non-tapered analysis windows functions (such as the rectangular window) significantly improves intelligibility of the phase spectrum. This improvement was attributed to the spectral characteristics of the non-tapered analysis windows and—in particular—to their low spectral dynamic range. The main aim of the research presented in this dissertation is to further examine the importance of the short-time phase spectrum for human speech perception. It is hoped that results of such an examination can provide an incentive for further research in this direction. Three studies that investigate the usefulness of the phase spectrum for human speech perception are presented in this thesis. These studies employ human listening tests to explore the importance of the phase spectrum for speech intelligibility, speaker dependent speech information and speech quality. In each of these studies the effect of the spectral dynamic range of an analysis window function is systematically examined.Thesis (PhD Doctorate)
Doctor of Philosophy (PhD)
Griffith School of Engineering
Science, Environment, Engineering and Technology
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Alsteris, Leigh, and n/a. "Short-Time Phase Spectrum in Human and Automatic Speech Recognition." Griffith University. School of Microelectronic Engineering, 2006. http://www4.gu.edu.au:8080/adt-root/public/adt-QGU20060727.090845.
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Incorporating information from the short-time phase spectrum into a feature set for automatic speech recognition (ASR) may possibly serve to improve recognition accuracy. Currently, however, it is common practice to discard this information in favour of features that are derived purely from the short-time magnitude spectrum. There are two reasons for this: 1) the results of some well-known human listening experiments have indicated that the short-time phase spectrum conveys a negligible amount of intelligibility at the small window durations of 20-40 ms used for ASR spectral analysis, and 2) using the short-time phase spectrum directly for ASR has proven di?cult from a signal processing viewpoint, due to phase-wrapping and other problems. In this thesis, we explore the possibility of using short-time phase spectrum information for ASR by considering the two points mentioned above. To address the ?rst point, we conduct our own set of human listening experiments. Contrary to previous studies, our results indicate that the short-time phase spectrum can indeed contribute signi?cantly to speech intelligibility over small window durations of 20-40 ms. Also, the results of these listening experiments, in addition to some ASR experiments, indicate that at least part of this intelligibility may be supplementary to that provided by the short-time magnitude spectrum. To address the second point (i.e., the signal processing di?culties), it may be necessary to transform the short-time phase spectrum into a more physically meaningful representation from which useful features could possibly be extracted. Speci?cally, we investigate the frequency-derivative (or group delay function, GDF) and the time-derivative (or instantaneous frequency distribution, IFD) as potential candidates for this intermediate representation. We have performed various experiments which show that the GDF and IFD may be useful for ASR. We conduct several ASR experiments to test a feature set derived from the GDF. We ?nd that, in most cases, these features perform worse than the standard MFCC features. Therefore, we suggest that a short-time phase spectrum feature set may ultimately be derived from a concatenation of information from both the GDF and IFD representations. For best performance, the feature set may also need to be concatenated with short-time magnitude spectrum information. Further to addressing the two aforementioned points, we also discuss a number of other speech applications in which the short-time phase spectrum has proven to be very useful. We believe that an appreciation for how the short-time phase spectrum has been used for other tasks, in addition to the results of our research, will provoke fellow researchers to also investigate its potential for use in ASR.
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Alsteris, Leigh. "Short-Time Phase Spectrum in Human and Automatic Speech Recognition." Thesis, Griffith University, 2006. http://hdl.handle.net/10072/366602.
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Incorporating information from the short-time phase spectrum into a feature set for automatic speech recognition (ASR) may possibly serve to improve recognition accuracy. Currently, however, it is common practice to discard this information in favour of features that are derived purely from the short-time magnitude spectrum. There are two reasons for this: 1) the results of some well-known human listening experiments have indicated that the short-time phase spectrum conveys a negligible amount of intelligibility at the small window durations of 20-40 ms used for ASR spectral analysis, and 2) using the short-time phase spectrum directly for ASR has proven di?cult from a signal processing viewpoint, due to phase-wrapping and other problems. In this thesis, we explore the possibility of using short-time phase spectrum information for ASR by considering the two points mentioned above. To address the ?rst point, we conduct our own set of human listening experiments. Contrary to previous studies, our results indicate that the short-time phase spectrum can indeed contribute signi?cantly to speech intelligibility over small window durations of 20-40 ms. Also, the results of these listening experiments, in addition to some ASR experiments, indicate that at least part of this intelligibility may be supplementary to that provided by the short-time magnitude spectrum. To address the second point (i.e., the signal processing di?culties), it may be necessary to transform the short-time phase spectrum into a more physically meaningful representation from which useful features could possibly be extracted. Speci?cally, we investigate the frequency-derivative (or group delay function, GDF) and the time-derivative (or instantaneous frequency distribution, IFD) as potential candidates for this intermediate representation. We have performed various experiments which show that the GDF and IFD may be useful for ASR. We conduct several ASR experiments to test a feature set derived from the GDF. We ?nd that, in most cases, these features perform worse than the standard MFCC features. Therefore, we suggest that a short-time phase spectrum feature set may ultimately be derived from a concatenation of information from both the GDF and IFD representations. For best performance, the feature set may also need to be concatenated with short-time magnitude spectrum information. Further to addressing the two aforementioned points, we also discuss a number of other speech applications in which the short-time phase spectrum has proven to be very useful. We believe that an appreciation for how the short-time phase spectrum has been used for other tasks, in addition to the results of our research, will provoke fellow researchers to also investigate its potential for use in ASR.Thesis (PhD Doctorate)
Doctor of Philosophy (PhD)
School of Microelectronic Engineering
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Rautiainen, J. (Jari). "Novel magnetic resonance imaging techniques for articular cartilage and subchondral bone:studies on MRI Relaxometry and short echo time imaging." Doctoral thesis, Oulun yliopisto, 2015. http://urn.fi/urn:isbn:9789526207643.
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Abstract Osteoarthritis is a common joint disease in the adult population characterized by degeneration and limited repair capability of articular cartilage. Cartilage degeneration is also associated with remodeling and sclerosis of the subchondral bone. The relative contributions of these processes are not fully understood partly because of a lack of proper biomarkers for the diagnosis and follow-up of the disease progress. Current diagnostic methods are too insensitive or subjective for reliable and early diagnosis of osteoarthritis. Novel magnetic resonance imaging (MRI) techniques can be used for indirect assessment of cartilage constituents. In addition, the imaging of the subchondral bone and osteochondral junction has become feasible, which has been very difficult with conventional MRI methods due to the very fast signal (T2) decay in those tissues. Quantitative MRI of cartilage involves measurement of relaxation time parameters (T1, T2, T1ρ, T2ρ, TRAFF, T1sat) and investigation of how the parameters reflect the properties of the cartilage. SWIFT (Sweep imaging with Fourier transform) is an MRI technique capable of imaging short T2 structures, enabling assessment of the osteochondral junction as well as the subchondral bone. The aim of this work was to investigate osteoarthritic changes occurring in articular cartilage and subchondral bone in experimental animal models of osteoarthritis and degenerated human specimens with quantitative MRI measurements and SWIFT imaging at 9.4 T. Moreover, the feasibility of the different quantitative MRI techniques in the assessment of osteoarthritic changes was studied. For reference, biomechanical, quantitative and qualitative histology, biochemical and micro-computed tomography measurements were conducted. Novel adiabatic T1ρ and T2ρ relaxation time parameters were more sensitive than conventional methods (T1, T2) or continuous wave T1ρ to both early degenerative changes in a rabbit model of cartilage degeneration and to spontaneous degeneration of human cartilage. SWIFT enabled assessment of the structural properties of the subchondral bone. Moreover, signal changes related to the degree of osteoarthritis were detected at the cartilage–bone interface with SWIFT. These methods may provide new tools for improving the diagnosis of early osteoarthritis. Further studies are needed to investigate the clinical feasibility of these MRI techniquesTiivistelmä Nivelrikko on yleinen nivelsairaus, johon ei tällä hetkellä ole parannuskeinoa. Nivelrikossa nivelrusto rappeutuu asteittain aiheuttaen lopulta kudoksen tuhoutumisen; samanaikaisesti myös rustonalaisessa luussa sekä rusto–luurajapinnassa tapahtuu muutoksia. Nivelrustokudoksen uusiutumiskyky on erittäin heikko, joten vauriot olisi hyvä havaita varhaisessa vaiheessa. Nivelrikon syntymekanismeja ei kuitenkaan vielä täysin ymmärretä, koska nykyiset seurantamenetelmät eivät ole riittävän tarkkoja taudin etenemisen tarkkailemiseksi. Magneettikuvausteknologian kehitys mahdollistaa kuitenkin nivelruston koostumuksen tarkastelun nivelen ulkopuolelta. Kvantitatiivisen magneettikuvauksen avulla (T1, T2, T1ρ, T2ρ, TRAFF, T1sat relaksaatioaikaparametrit) voidaan mitata epäsuorasti nivelruston koostumusta ja rakennetta. SWIFT (Sweep Imaging with Fourier Transform) on uusi lyhyen kaikuajan magneettikuvausmenetelmä, joka mahdollistaa myös erittäin lyhyen T2-relaksaatioajan omaavien kudosten, kuten rusto–luurajapinnan sekä rustonalaisen luun kuvaamisen. Työssä tutkittiin nivelrikossa syntyviä muutoksia nivelrustossa, rusto–luurajapinnassa ja rustonalaisessa luussa erilaisissa eläinmalleissa sekä ihmiskudoksessa. Lisäksi työssä tarkasteltiin eri magneettikuvaustekniikoiden herkkyyttä havaita muutokset näissä kudoksissa. Nivelruston ja rustonalaisen luun ominaisuuksien määrittelemiseen käytettiin verrokkimenetelminä biomekaanisia, histologisia sekä biokemiallisia mittauksia ja tietokonetomografiakuvauksia. Kvantitatiivisista magneettikuvausparametreista adiabaattinen T1ρ sekä adiabaattinen T2ρ osoittautuivat herkimmiksi havaitsemaan muutoksia varhaisen nivelrikon eläinmallissa sekä ihmiskudosnäytteissä. SWIFT-magneettikuvaustekniikka puolestaan mahdollisti sekä rustonalaisen luukudoksen tilan arvioinnin että nivelrikossa tapahtuvien muutosten havainnoinnin rusto–luurajapinnassa. Nämä menetelmät voivat mahdollistaa nivelrikon diagnosoinnin taudin varhaisessa vaiheessa, mutta lisätutkimuksia vaaditaan menetelmien soveltuvuudesta kliiniseen käyttöön
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Helienek, Matúš. "Simulační a experimentální analýza řezání kotoučovou pilou." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2018. http://www.nusl.cz/ntk/nusl-412924.
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This thesis deals with analysis of dynamic forces and vibrations created during cutting with saw. The analysis is done on both simulation and experimental level. Acquired signals are evaluated with signal tools as STFT, CWT and DWT.
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Gavrilovic, Nenad. "VIBRATION-BASED HEALTH MONITORING OF ROTATING SYSTEMS WITH GYROSCOPIC EFFECT." DigitalCommons@CalPoly, 2015. https://digitalcommons.calpoly.edu/theses/1358.
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This thesis focuses on the simulation of the gyroscopic effect using the software MSC Adams. A simple shaft-disk system was created and parameter of the sys-tem were changed in order to study the influence of the gyroscopic effect. It was shown that an increasing bearing stiffness reduces the precession motion. Fur-thermore, it was shown that the gyroscopic effect vanishes if the disk of system is placed symmetrically on the shaft, which reduces the system to a Jeffcott-Ro-tor. The second objective of this study was to analyze different defects in a simple fixed axis gear set. In particular, a cracked shaft, a cracked pinion and a chipped pinion as well as a healthy gear system were created and tested in Adams. The contact force between the two gears was monitored and the 2D and 3D frequency spectrum, as well as the Wavelet Transform, were plotted in order to compare the individual defects. It was shown that the Wavelet Transform is a powerful tool, capable of identifying a cracked gear with a non-constant speed. The last part of this study included fault detection with statistical methods as well as with the Sideband Energy Ratio (SER). The time domain signal of the individual faults were used to compare the mean, the standard deviation and the root mean square. Furthermore, the noise profile in the frequency spectrum was tracked with statistical methods using the mean and the standard deviation. It was demonstrated that it is possible to identify a cracked gear, as well as a chipped gear, with statistical methods. However, a cracked shaft could not be identified. The results also show that SER was only capable to identify major defects in a gear system such as a chipped tooth.
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Kovačev, Radovan. "Časově-frekvenční analýza signálu." Master's thesis, Vysoké učení technické v Brně. Fakulta informačních technologií, 2012. http://www.nusl.cz/ntk/nusl-236491.
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The main subject of this work represents the time-frequency signal analysis. Firstly, it intends to provide the most essential theoretical background with focus on the continuous wavelet transform, where also a comparison of the key features with its close relative the short-time Fourier transform is performed. Afterwards, there follows a demonstration of the purpose with a practical example. The particular aim is to create a phase vocoder solution for modifying the length of a sound record duration and pitch shifting. Here, in this place, the functional principles, design, procedure of assembling, outputs and achieved results are well documented.
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Qin, Xuefei. "Measurement of horses gaits using geo-sensors." Thesis, Högskolan i Gävle, Avdelningen för elektronik, matematik och naturvetenskap, 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:hig:diva-17769.
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The aim of this thesis is to determine the horse’s gait types using the acceleration values measured from the horse. A measurement was taken in Gävletravet, a total of five Nanotrak sensors were used, four on the different parts of the horse, and one on the hand of the horse’s driver, a car was driven parallel to the horse and the motions of the horse was recorded by a camera in order to synchronize with the data measured by the sensors, a total of four videos were recorded. The software to process the data was Matlab R2010b, and the methods to analyze them were Fast Fourier Transform (FFT), Short Time Fourier Transform (STFT), and Least Squares (LS). Different window functions were tried when applying the STFT, and the Hanning window was the best to smooth the curves, different window sizes (or data length) were also tried, the data length of 512 was found to be the most proper value. The methods for classification of horse’s gaits included amplitude, ratio, and LS. The method of amplitude worked well for the first three videos except for the last one, and performed better than the other two. The method of ratio was more reliable, but the results were not satisfactory. The method of LS gave bad results, so it was not trustworthy. More measurements and more analysis needed to be done in the future to find a proper way to automatic determine the horse’s gaits, and the use of modern technology will be very popular in other fields like animal science.
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Catelli, Ezio. "Representation functions in Signal Processing." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2017. http://amslaurea.unibo.it/13530/.
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Scopo dell'elaborato è presentare la trasformata windowed seguendo un approccio di modellizzazione matematica. La parte di teoria verte sui contenuti fondamentali e di specifico interesse per la trattazione nel capo della signal analysis di short-time Fourier transform e Wigner-Ville distribution. La parte di pratica presenta esempi svolti al calcolatore.
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Bechtold, Bastian [Verfasser], de Par Steven [Akademischer Betreuer] van, Jörg [Akademischer Betreuer] Bitzer, and Udo [Akademischer Betreuer] Zölzer. "Pitch of Voiced Speech in the Short-Time Fourier Transform: Algorithms, Ground Truths, and Evaluation Methods / Bastian Bechtold ; Steven van de Par, Jörg Bitzer, Udo Zölzer." Oldenburg : BIS der Universität Oldenburg, 2021. http://d-nb.info/1232405213/34.
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Bartůšek, Jan. "Time Frequency Analysis of ERP Signals." Master's thesis, Vysoké učení technické v Brně. Fakulta informačních technologií, 2007. http://www.nusl.cz/ntk/nusl-412769.
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Tato práce se zabývá vylepšením algoritmu pro sdružování (clustering) ERP signálů pomocí analýzy časových a prostorových vlastností pseudo-signálů získaných za pomocí metody analýzy nezávislých komponent (Independent Component Analysis). Naším zájmem je nalezení nových vlastností, které by zlepšily stávající výsledky. Tato práce se zabývá použitím Fourierovy transformace (Fourier Transform), FIR filtru a krátkodobé Fourierovy transformace ke zkvalitnění informace pro sdružovací algoritmy. Princip a použitelnost metody jsou popsány a demonstrovány ukázkovým algoritmem. Výsledky ukázaly, že pomocí dané metody je možné získat ze vstupních dat zajímavé informace, které mohou být úspěšně použity ke zlepšení výsledků.
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El, Gemayel Tarek. "Feasibility of Using Electrical Network Frequency Fluctuations to Perform Forensic Digital Audio Authentication." Thèse, Université d'Ottawa / University of Ottawa, 2013. http://hdl.handle.net/10393/24383.
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Extracting the Electric Network Frequency (ENF) fluctuations from an audio recording and comparing it to a reference database is a new technology intended to perform forensic digital audio authentication. The objective of this thesis is to implement and design a range of programs and algorithms for capturing and extracting ENF signals. The developed C-program combined with a probe can be used to build the reference database. Our implementation of the Short-Time Fourier Transform method is intended for the ENF extraction of longer signals while our novel proposed use of the Autoregressive parametric method and our implementation of the zero-crossing approach tackle the case of shorter recordings. A Graphical User Interface (GUI) was developed to facilitate the process of extracting the ENF fluctuations. The whole process is tested and evaluated for various scenarios ranging from long to short recordings.
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Fendrychová, Michaela. "Detekce elektrického oblouku." Master's thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2016. http://www.nusl.cz/ntk/nusl-241952.
Full textAbstract:
Diplomová práce je zaměřena na problematiku analýzy signálů za účelem detekce poruchového oblouku, přičemž analýza signálů je prováděna v časové, frekvenční a smíšené časově-frekvenční oblasti. Práce stručně shrnuje existující normy pro zařízení pro detekci poruchového oblouku. Práce dokumentuje testy a měření, které byly realizovány v souladu s normami IEC 62606:2013 a UL 1699B. Z důvodu nedostatečnosti stávajících norem je v práci popsána nová metoda iniciace poruchového oblouku. naměřená data byla analyzována s využitím rychlé Fourierovy transformace, krátkodobé Fourierovy transformace a vlnkové transformace. Na základě provedeného literárního průzkumu a s využitím výsledků provedených analýz signálu je v práci proveden návrh nové detekční metody pro účely detekce poruchového oblouku v systémech napájených střídavým i stejnosměrným napětím.
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Hodkiewicz, Melinda R. "The effect of partial-flow operation on the axial vibration of double-suction centrifugal pumps." University of Western Australia. School of Mechanical Engineering, 2005. http://theses.library.uwa.edu.au/adt-WU2005.0067.
Full textAbstract:
[Truncated abstract] Centrifugal pumps are designed to operate at a capacity that maximizes the efficiency of the pump. Operation below this design capacity results in reduction of pump efficiency as the geometric configuration of the impeller and casing no longer provide an ideal flow pattern. Consequently there are changes in the flow field within the pump, including flow separation and regions of localized, non-uniform, unsteady flow. This flow interacts with rotating and stationary components inside the pump creating additional disturbance and hydraulic excitation. It is anticipated that the local hydrodynamic and global hydroacoustic excitation due to partial-flow operation will affect the structural vibration measured on the pump. In this study, the effects of partial-flow operation on the vibration signal at the pump bearing housing are measured on a number of industrial double-suction pump units. These are a particular class of centrifugal pump commonly used in high volume applications such as water distribution. The aims are to understand how the vibration signals change at the different operating conditions and to determine which parameters are best suited to monitoring the observed changes. Comparison is made between the response, under similar operating conditions, of pumps both within sets of identical size and design, across sets of similar design and different sizes, and between different designs. The pumps are all in-service industrial units. In double-suction pumps the impeller motion in the axial direction (along the line of the shaft) is not constrained. Due to symmetry in impeller design, axial stability is maintained by equal and opposite hydraulic forces on the two opposing sides of the impeller. The potential for loss of axial hydraulic balance during partial-flow operation is examined from a theoretical perspective, based on a literature review, and by measurement of the axial displacement of the shaft. Structural vibration is measured using accelerometers mounted at the non-drive end bearing housing in the horizontal and axial orientations. Changes in signal contribution and characteristics are examined using a variety of qualitative and quantitative techniques. Test signals are used to assess the limitations of the techniques and the effect of parameter selection on the interpretation of the signals.
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Löfgren, Isabelle. "Interharmonic Analysis of Sustainable Energy Sources and Loads : Comparing two signal processing methods for estimation of interharmonics." Thesis, Högskolan Dalarna, Energiteknik, 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:du-34236.
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In this report, studies on interharmonics from three different measurement sites are performed. The first site is a wind park with three turbines, where the measurements are performed at the point of common coupling of these three. The second site is a network which consists of a PV inverter and two types of EV chargers – a DC charger or an AC charger. Measurements are performed with three different set-ups in this site – only AC charger connected, only DC charger connected, and AC charger and PV inverter connected simultaneously. The third site where measurements were made is a microgrid using frequency control in order to signal how the microgrid should operate at the moment. The interharmonic analysis was conducted using desynchronized processing technique (DP) and Sliding-Window Estimation of Signal Parameters via Rotational Invariance Techniques (SlidingWindow ESPRIT or SWESPRIT). The result from the wind park is that closely and evenly spaced interharmonics can be seen when the current suddenly increases (could be fast variations in wind speed). It is however uncertain if these interharmonics are caused by spectral leakage or not since SWESPRIT estimates the fundamental frequency to vary drastically when wind speed varies. It is observed that the SWESPRIT estimation of fundamental frequency could be caused by sudden changes in phase angle as the current varies. Further investigation and analysis are needed. The result from the measurements on the site with EV chargers and a PV inverter is that eight distinct patterns can be observed. Some patterns appear to come from the upstream grid, while some appear to be caused by either one of the EV chargers or the PV inverter, or interaction between them. Further studies are needed. The result from the microgrid measurements is that two distinct patterns at high frequencies (above 1000 Hz) can be observed during grid connected mode and island mode, respectively. During transitions between grid connection and island mode or vice versa, the fundamental frequency varies drastically, and it is therefore hard to analyse potential interharmonics and draw inferences. Further studies are needed. Advantages and disadvantages, as well as ideas for improvements, of the two applied signal processing methods are discussed throughout the different case-studies.
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Mercat, Benjamin. "Analyse temps-fréquence en mécanique cellulaire et adaptabilité du fuseau mitotique." Thesis, Rennes 1, 2016. http://www.theses.fr/2016REN1S124/document.
Full textAbstract:
Le fuseau mitotique assure la ségrégation des chromatides sœurs et le maintien de la poïdie des cellules filles. Le fuseau est composé de microtubules dynamiques (qui polymérisent et dépolymérisent continuellement), de nombreux moteurs moléculaires, d'agents de réticulations et de régulateurs. Bien que la structure du fuseau au niveau moléculaire soit connue, son fonctionnement reste délicat à comprendre, et nécessite la prise en compte de la dynamique de ses composants et leurs interactions. Les approches utilisées pour répondre à ces problématiques sont jusqu'à maintenant plutôt des approches in silico et in vitro. Il manque aujourd'hui une caractérisation de la mécanique du fuseau dans son contexte physiologique. Nous proposons une méthode non invasive basée sur de l'analyse d'image, combiné à une modélisation heuristique pour mesurer les paramètres mécaniques durant toute la division. Nous suivons les pôles du fuseau marqués par protéine fluorescente avec un taux acquisition rapide et une bonne résolution spatiale ce qui nous permet d'accéder aux fluctuations de longueur du fuseau in vivo. Avec la transformée de Fourier aux temps courts, nous calculons leurs densités spectrales de puissances — leurs signatures mécaniques. Ces spectres sont alors ajustés avec un modèle Kelvin — Voigt avec inertie (un ressort, un amortisseur et un terme inertiel en parallèle). Nous avons validé la méthode par des expériences numériques où nous retrouvons les évolutions des paramètres sur des données simulées et la calibration a été réalisée par l'utilisation de la rupture du fuseau induite par micro chirurgie laser ou par la génétique. Nous avons caractérisé le fuseau de l'embryon unicellulaire du nématode C. elegans. La méthaphase apparaît dominée par l'amortisseur, ce qui est cohérent avec la lente élongation du fuseau que nous observons. Mais contraste l'idée répandue de l'existence d'un mécanisme de maintien de la longueur du fuseau durant la métaphase. Au passage en anaphase, les trois paramètres mécaniques chutent, avant de réaugmenter environ 50 secondes après la transition pour réatindre un régime dominé de nouveau par l'amortisseur, ce qui suggère que les microtubules interpolaires jouent un rôle mineur durant l'élongation du fuseau en début d'anaphase. Dans la perspective de comprendre le lien entre la mécanique du fuseau et les interactions des acteurs moléculaires, nous avons partiellement supprimé un gène par sous-structure du fuseau. Nous avons alors retrouvé des comportements connus avec une perspective augmentée offerte par notre méthode. Cette méthode, ne va pas seulement permettre la compréhension fondamentale de la mécanique du fuseau, en remplaçant la modélisation du fuseau basé uniquement sur la longueur, mais aussi d'aller vers la prise en compte de la robustesse de fonctionnement du fuseau mitotique face aux défauts tel que la polyou l'aneuploïdieThe mitotic spindle ensures the correct segregation of the sister chromatids to maintain ploidy in daughter cells. The spindle comprises dynamical microtubules (alternating polymerizing and depolymerizing), a variety of molecular motors, crosslinker and the regulators. Although the molecular grounds of spindle structure is well known, the link to its functions remain elusive, calling for including the dynamics of its components and their interactions. These questions were mostly investigated by in silico or in vitro approaches. But a detailed characterizing of spindle mechanics, in physiological conditions, is missing. We propose an image processing based, non invasive, method combined to an heuristic model to measure mechanical parameters of the mitotic spindle along time. We tracked fluorescently labeled spindle pole at high temporal and spatial resolution and measured the variations of spindle length, in vivo. We computed their power density spectrum using short time Fourier transform (sliding window) — a blueprint of spindle mechanics. Such a spectrum is then fitted with a Kelvin —Voigt model with inertia (a spring, a damper, an inertial element in parallel). We validated this method by recovering the mechanical parameters over time from simulated data and calibrated it uses laser and genetically induced spinlde cut. We characterized the mitotic spindle of the one-cell embryo of nematode C. elegans. Metaphase appeared dominated by damping element, consistent with the slow spindle elongation observed. But in contrast with the common thought that a mechanism maintains the spindle length during metaphase. At anaphase onset, all three parameters collapsed, before increasing about 50s later to reach a regime where damping dominated again, suggesting the overlapping spinlde microtubules may play a minor role in early anaphase spinlde elongation. In perspective of understanding how spindle mechanics emerge of molecular players interactions, we depleted one gene per splindle sub-structure — overlapped microtubules, kinetochore microtubules, central spindle and astral microtubules. We succefully recovered some known behavior but with the augmented insight offered by our method. This method paves the way not only towards understanding the fundamentals of spindle mechanics, superseding the degenerated modeling based on the sole spindle length but also towards acounting for spindle functional robustness towards defect as polyor aneuploidy
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Pyon, Okmin. "The data processing to detect correlated movement of Cerebral Palsy patient in early phase." Thesis, Virginia Tech, 2016. http://hdl.handle.net/10919/64776.
Full textAbstract:
The early diagnosis of CP (Cerebral Palsy) in infants is important for developing meaningful interventions. One of the major symptoms of the CP is lack of the coordinated movements of a baby. The bilateral coordinated movement (BCM) is that a baby shows in the early development stage. Each limb movement shows various ranges of speed and angle with fluency in a normal infant. When a baby has CP the movements are cramped and more synchronized.
A quantitative method is needed to diagnose the BCM. Data is collected from 3-axis accelerometers, which are connected, to each limb of the baby. Signal processing the collected data using short time Fourier transforms, along with the formation of time-dependent transfer functions and the coherence property is the key to the diagnostic approach. Combinations of each limb's movement and their relationship can represent the correlated movement. Data collected from a normal baby is used to develop the technique for identifying the fidgety movement. Time histories and the resulting diagnostic tool are presented to show the regions of the described movement. The evaluation of the transduction approach and the analysis is discussed in detail.
The application of the quantitative tool for the early diagnosis of CP offers clinicians the opportunity to provide interventions that may reduce the debilitating impact this condition has on children. Tools such as this can also be used to assess motor development in infants and lead to the identification and early intervention for other conditions.Master of Science
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Liu, Qingling. "Pilot-induced oscillation detection and mitigation." Thesis, Cranfield University, 2012. http://dspace.lib.cranfield.ac.uk/handle/1826/7998.
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Commercial Aircraft
Corporation of China, Ltd (COMAC)and Chinese Scholarship Council.The aim of this thesis is to develop a real time PIO detection and mitigation system that consists of a detector based on short time Fourier transform(STFT) and autoregressive model(ARX) with exogenous inputs, together with an adaptive controller based mitigation system. The system not only detects the traditional PIO characteristics but also focuses on the trend of pilot behaviour by calculating the rate of change in the open loop crossover frequency. In the detection system, a sliding windowed STFT method was applied to identify the frequency and phase characteristics of the system via processing the signal of pilot input and aircraft state. An ARX model was also applied to get the rate of change of the crossover frequency. After detection, a PIO cue was shown on the primary flight display. A scheduled gain controller was coupled to provide PIO mitigation by varying stick input gain. Compensatory and tracking tests for the evaluation of this system were performed using a quasi-linear Boeing-747 aircraft model including nonlinear command gearing and actuator rate-limiting. Bandwidth and Gibson criteria were used to design PIO prone control laws for system evaluation experiments. Results from PIO tests conducted on desktop PCs were presented. These were analyzed and compared with those obtained from implementing the Real-time Oscillation Verifier module available in literature.
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Tuleja, Peter. "Využití Hilbert Huangovy transformace pro analýzu nestacionárních signálů z fyzikálních experimentů." Master's thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2014. http://www.nusl.cz/ntk/nusl-220614.
Full textAbstract:
This paper discusses the possible use of Hilbert-Huang transform to analyze the data obtained from physical experiments. Specifically for the analysis of acoustic emission in the form of acoustic shock. The introductory section explains the concept of acoustic emission and its detection process. Subsequently are discussed methods for signal analysis in time-frequency domain. Specifically, short-term Fourier transform, Wavelet transform, Hilbert transform and Hilbert-Huang transform. The final part contains the proposed method for measuring the performance and accuracy of different approaches.
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Dias, Fernando Luis. "Um esquema de Fourier local para análise tempo-frequência de sinais não-estacionários aplicado a ruído eletroquímico." Universidade do Estado do Rio de Janeiro, 2014. http://www.bdtd.uerj.br/tde_busca/arquivo.php?codArquivo=7720.
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Coordenação de Aperfeiçoamento de Pessoal de Nível SuperiorSinais diversos estão presentes em nosso cotidiano, assim como nas medidas realizadas nas atividades de ciência e tecnologia. Dentre estes sinais, tem grande importância tecnológica aqueles associados à corrosão de estruturas metálicas. Assim, esta tese propõe o estudo de um esquema local de transformada de Fourier janelada, com a janela variando em função da curtose, aplicada a sinais de ruído eletroquímico. A curtose foi avaliada nos domínios do tempo e da frequência e processada pelo programa desenvolvido para esse fim. O esquema foi aplicado a sinais de ruído eletroquímico dos aços UNS S31600, UNS G10200 e UNS S32750 imersos em três soluções: FeCl3 0,1 mol=L (cloreto férrico), H2SO4 5%(ácido sulfúrico) e NaOH 0,1%(hidróxido de sódio). Para os aços inoxidáveis, estas soluções promovem corrosão localizada, uniforme e passivação, respectivamente. Visando testar o desempenho do esquema de Fourier desenvolvido, testes foram realizados utilizando-se inicialmente sinais sintéticos e em seguida sinais de ruído eletroquímico. Notou-se que os sinais têm características de não-estacionaridade e a maior parte da energia está presente em baixa frequência. Os intervalos de tempo e de frequência onde se concentra a maior parte da energia do sinal foram correlacionados. Para os picos máximos dos sinais de potencial e corrente obtidos de amperimetria de resistência nula, a correlação entre eles foi baixa, independente da forma de corrosão presente. Conclui-se que o método se adaptou bastante bem às características locais do sinal eletroquímico permitindo o monitoramento dos espectros tempo-frequência. O fato de ser sensível às características locais do sinal permite analisar aspectos dos sinais que do modo clássico não podem ser diretamente processados. O método da transformada de Fourier janelada variável (Variable Short-Time Fourier Transform - VSTFT) adaptou-se muito bem no monitoramento dos sinais originados de potencial de circuito aberto e amperimetria de resistência nula.
Several signals are present in our daily lives, as well as in the measurements from scientific and technological procedures. Among these signals, it has great technological importance those associated with corrosion of metallic structures. Thus, this thesis considers a local windowed Fourier transform, varying according to the kurtosis of signals, applied to electrochemical noise. The kurtosis was assessed in the kurtosis of the time and frequency domains and evaluated by the software developed for this purpose. The scheme has been applied to electrochemical noise signals of UNS S31600, UNS G10200 and UNS S32750 steels immersed in three solutions: FeCl3 0.1 mol=L (ferric chloride), H2SO4 5 % (sulfuric acid) and NaOH 0.1 % (sodium hydroxide). For stainless steels, these solutions cause localized corrosion, uniform corrosion and passivation, respectively. To test the performance of the proposed Fourier scheme, tests were conducted initially using synthetic signal and then electrochemical noise signals. It is worth noticing that the signals have non-stationary characteristics and most part of its energy is present at low frequency. The time and frequency intervals which concentrate most part of the energy of the signal were correlated. For the maximum peaks of the potential and current signals obtained by zero resistance ammeter, the correlation between them was low, regardless of the form of present corrosion. We conclude that the method is well adapted to the local features of the electrochemical signal allowing the monitoring of time-frequency spectograms. As the method is sensitive to the local features of the sign, it allows to analyse signals that by the classic approach can not be directly processed. The windowed Fourier transform (Variable Short-Time Fourier Transform - VSTFT) adapted very well in monitoring of the signals originated by open circuit potential and zero resistance ammeter.
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Kasaei, Shohreh. "Fingerprint analysis using wavelet transform with application to compression and feature extraction." Thesis, Queensland University of Technology, 1998. https://eprints.qut.edu.au/36053/7/36053_Digitised_Thesis.pdf.
Full textAbstract:
The main goal of this research is to design an efficient compression al~
gorithm for fingerprint images. The wavelet transform technique is the
principal tool used to reduce interpixel redundancies and to obtain a parsimonious
representation for these images. A specific fixed decomposition
structure is designed to be used by the wavelet packet in order to save on the
computation, transmission, and storage costs. This decomposition structure
is based on analysis of information packing performance of several decompositions,
two-dimensional power spectral density, effect of each frequency
band on the reconstructed image, and the human visual sensitivities. This
fixed structure is found to provide the "most" suitable representation for
fingerprints, according to the chosen criteria.
Different compression techniques are used for different subbands, based
on their observed statistics. The decision is based on the effect of each subband
on the reconstructed image according to the mean square criteria as
well as the sensitivities in human vision. To design an efficient quantization
algorithm, a precise model for distribution of the wavelet coefficients is developed.
The model is based on the generalized Gaussian distribution. A least
squares algorithm on a nonlinear function of the distribution model shape
parameter is formulated to estimate the model parameters. A noise shaping
bit allocation procedure is then used to assign the bit rate among subbands.
To obtain high compression ratios, vector quantization is used. In this
work, the lattice vector quantization (LVQ) is chosen because of its superior
performance over other types of vector quantizers. The structure of a lattice
quantizer is determined by its parameters known as truncation level and scaling
factor. In lattice-based compression algorithms reported in the literature
the lattice structure is commonly predetermined leading to a nonoptimized
quantization approach. In this research, a new technique for determining the
lattice parameters is proposed. In the lattice structure design, no assumption
about the lattice parameters is made and no training and multi-quantizing
is required. The design is based on minimizing the quantization distortion
by adapting to the statistical characteristics of the source in each subimage.
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Abstract Abstract
Since LVQ is a multidimensional generalization of uniform quantizers, it
produces minimum distortion for inputs with uniform distributions. In order
to take advantage of the properties of LVQ and its fast implementation,
while considering the i.i.d. nonuniform distribution of wavelet coefficients,
the piecewise-uniform pyramid LVQ algorithm is proposed. The proposed
algorithm quantizes almost all of source vectors without the need to project
these on the lattice outermost shell, while it properly maintains a small codebook
size. It also resolves the wedge region problem commonly encountered
with sharply distributed random sources. These represent some of the drawbacks
of the algorithm proposed by Barlaud [26). The proposed algorithm
handles all types of lattices, not only the cubic lattices, as opposed to the algorithms
developed by Fischer [29) and Jeong [42). Furthermore, no training
and multiquantizing (to determine lattice parameters) is required, as opposed
to Powell's algorithm [78).
For coefficients with high-frequency content, the positive-negative mean
algorithm is proposed to improve the resolution of reconstructed images.
For coefficients with low-frequency content, a lossless predictive compression
scheme is used to preserve the quality of reconstructed images. A method
to reduce bit requirements of necessary side information is also introduced.
Lossless entropy coding techniques are subsequently used to remove coding
redundancy.
The algorithms result in high quality reconstructed images with better
compression ratios than other available algorithms. To evaluate the proposed
algorithms their objective and subjective performance comparisons
with other available techniques are presented.
The quality of the reconstructed images is important for a reliable identification.
Enhancement and feature extraction on the reconstructed images
are also investigated in this research. A structural-based feature extraction
algorithm is proposed in which the unique properties of fingerprint textures
are used to enhance the images and improve the fidelity of their characteristic
features. The ridges are extracted from enhanced grey-level foreground areas
based on the local ridge dominant directions. The proposed ridge extraction
algorithm, properly preserves the natural shape of grey-level ridges as well as
precise locations of the features, as opposed to the ridge extraction algorithm
in [81). Furthermore, it is fast and operates only on foreground regions, as
opposed to the adaptive floating average thresholding process in [68). Spurious
features are subsequently eliminated using the proposed post-processing
scheme.
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Přikryl, Petr. "Porovnání úspěšnosti vícekanálových metod separace řečových signálů." Master's thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2008. http://www.nusl.cz/ntk/nusl-217519.
Full textAbstract:
The separation of independent sources from mixed observed data is a fundamental problem in many practical situations. A typical example is speech recordings made in an acoustic environment in the presence of background noise or other speakers. Problems of signal separation are explored by a group of methods called Blind Source Separation. Blind Source Separation (BSS) consists on estimating a set of N unknown sources from P observations resulting from the mixture of these sources and unknown background. Some existing solutions for instantaneous mixtures are reviewed and in Matlab implemented , i.e Independent Componnent Analysis (ICA) and Time-Frequency Analysis (TF). The acoustic signals recorded in real environment are not instantaneous, but convolutive mixtures. In this case, an ICA algorithm for separation of convolutive mixtures in frequency domain is introduced and in Matlab implemented. This diploma thesis examines the useability and comparisn of proposed separation algorithms.
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Akinci, Berna. "Realization Of A Cue Based Motor Imagery Brain Computer Interface With Its Potential Application To A Wheelchair." Master's thesis, METU, 2010. http://etd.lib.metu.edu.tr/upload/12612607/index.pdf.
Full textAbstract:
This thesis study focuses on the realization of an online cue based Motor Imagery (MI) Brain Computer Interface (BCI). For this purpose, some signal processing and classification methods are investigated. Specifically, several time-spatial-frequency methods, namely the Short Time Fourier Transform (STFT), Common Spatial Frequency Patterns (CSFP) and the Morlet Transform (MT) are implemented on a 2-class MI BCI system. Distinction Sensitive Learning Vector Quantization (DSLVQ) method is used as a feature selection method. The performance of these methodologies is evaluated with the linear and nonlinear Support Vector Machines (SVM), Multilayer Perceptron (MLP) and Naive Bayesian (NB) classifiers. The methodologies are tested on BCI Competition IV dataset IIb and an average kappa value of 0.45 is obtained on the dataset. According to the classification results, the algorithms presented here obtain the 4th level in the competition as compared to the other algorithms in the competition.
Offline experiments are performed in METU Brain Research Laboratories and Hacettepe Biophysics Department on two subjects with the original cue-based MI BCI paradigm. Average prediction accuracy of the methods on a 2-class BCI is evaluated to be 76.26% in these datasets. Furthermore, two online BCI applications are developed: the ping-pong game and the electrical wheelchair control. For these applications, average classification accuracy is found to be 70%.
During the offline experiments, the performance of the developed system is observed to be highly dependent on the subject training and experience. According to the results, the EEG channels P3 and P4, which are considered to be irrelevant with the motor imagination, provided the best classification performance on the offline experiments. Regarding the observations on the experiments, this process is related to the stimulation mechanism in the cue based applications and consequent visual evoking effects on the subjects.
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Rodrigues, Letícia Caldeira Pereira. "Técnicas para a detecção, classificação e localização no tempo das variações de tensão de curta e longa duração." Universidade de São Paulo, 2008. http://www.teses.usp.br/teses/disponiveis/18/18154/tde-04032009-150846/.
Full textAbstract:
Os objetivos deste trabalho vão da apresentação do andamento das pesquisas relacionadas à análise de distúrbios associados à qualidade da energia elétrica (QEE), até a proposta de um algoritmo baseado em diversas ferramentas para a detecção e localização no tempo, bem como a classificação automática destes distúrbios. Nesta pesquisa é proposta uma detecção não somente do início e fim de um único evento, mas também, de n possíveis desconformidades na forma de onda que possam vir a ocorrer ou existir em determinados registros e/ou arquivos de dados em análise. Como diferencial deste trabalho, tem-se que da determinação da localização das alterações/descontinuidades na forma de onda, foi possível obter janelas de dados com tamanhos flexíveis. Desta maneira, vários eventos sobre o sinal em análise puderam ser avaliados, bem como as durações associadas. Para isso, a Transformada Wavelet (TW) foi utilizada para realizar a detecção e também a localização destas alterações no tempo. Já para a classificação da ocorrência, ou das ocorrências, a TW, a Transformada de Fourier (TF) e o valor RMS foram empregados. A flexibilidade das janelas de dados permitiu uma adequada escolha de qual ferramenta poderia ser mais bem utilizada na classificação. Conforme implementado, cada uma destas ferramentas apresenta uma resposta e através de um módulo de decisão lógica é determinada a resposta final do algoritmo. Para validar o estudo, várias situações de distúrbios foram caracterizadas referentes a um sistema elétrico de distribuição real, implementado e simulado pela aplicação do software ATP (Alternative Transients Program). Os resultados obtidos foram excelentes tanto para a detecção e localização no tempo, como para a classificação e estimação da amplitude e duração dos eventos.The objectives of this work are going since the presentation of the researches related to the analyses of power quality (PQ) disturbances through the proposal of an algorithm based on several tools for detection and location in time, as well as the automatic classification of these phenomena. It is proposed to determine not only the initial and the end of a unique event, but all the n possible disconformities in the waveform that can exist or occur in the data file registered data in analyses. As the differential of this research, from the location in time of the alteration/discontinuities in the waveforms, it was possible to obtain data windows with flexible sizes. So, several events on the signal were evaluated, as well as their specific timeduration. For this purpose, the Wavelet transform (WT) was used to reach the detection and localization in time of the waveform alterations. For the event classification, the TW, the Fourier transform (FT) and the Root Mean Square (RMS) value were used. The data window flexibility allowed an appropriate choice of which tool could be better used in the classification task. As implemented, each one of these tools presented an answer, and the final answer was obtained by using a logic decision module. To validate the study, some situations of disturbances were characterized using a real distribution system, implemented and simulated applying the ATP (Alternative Transients Program) software. The results were excellent in such a way for detection and localization in time, as well as for the automatic classification and estimation of the magnitude and the event duration.
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Kaphle, Manindra R. "Analysis of acoustic emission data for accurate damage assessment for structural health monitoring applications." Thesis, Queensland University of Technology, 2012. https://eprints.qut.edu.au/53201/1/Manindra_Kaphle_Thesis.pdf.
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Structural health monitoring (SHM) refers to the procedure used to assess the condition of structures so that their performance can be monitored and any damage can be detected early. Early detection of damage and appropriate retrofitting will aid in preventing failure of the structure and save money spent on maintenance or replacement and ensure the structure operates safely and efficiently during its whole intended life. Though visual inspection and other techniques such as vibration based ones are available for SHM of structures such as bridges, the use of acoustic emission (AE) technique is an attractive option and is increasing in use. AE waves are high frequency stress waves generated by rapid release of energy from localised sources within a material, such as crack initiation and growth. AE technique involves recording these waves by means of sensors attached on the surface and then analysing the signals to extract information about the nature of the source. High sensitivity to crack growth, ability to locate source, passive nature (no need to supply energy from outside, but energy from damage source itself is utilised) and possibility to perform real time monitoring (detecting crack as it occurs or grows) are some of the attractive features of AE technique.
In spite of these advantages, challenges still exist in using AE technique for monitoring applications, especially in the area of analysis of recorded AE data, as large volumes of data are usually generated during monitoring. The need for effective data analysis can be linked with three main aims of monitoring: (a) accurately locating the source of damage; (b) identifying and discriminating signals from different sources of acoustic emission and (c) quantifying the level of damage of AE source for severity assessment.
In AE technique, the location of the emission source is usually calculated using the times of arrival and velocities of the AE signals recorded by a number of sensors. But complications arise as AE waves can travel in a structure in a number of different modes that have different velocities and frequencies. Hence, to accurately locate a source it is necessary to identify the modes recorded by the sensors. This study has proposed and tested the use of time-frequency analysis tools such as short time Fourier transform to identify the modes and the use of the velocities of these modes to achieve very accurate results. Further, this study has explored the possibility of reducing the number of sensors needed for data capture by using the velocities of modes captured by a single sensor for source localization.
A major problem in practical use of AE technique is the presence of sources of AE other than crack related, such as rubbing and impacts between different components of a structure. These spurious AE signals often mask the signals from the crack activity; hence discrimination of signals to identify the sources is very important. This work developed a model that uses different signal processing tools such as cross-correlation, magnitude squared coherence and energy distribution in different frequency bands as well as modal analysis (comparing amplitudes of identified modes) for accurately differentiating signals from different simulated AE sources.
Quantification tools to assess the severity of the damage sources are highly desirable in practical applications. Though different damage quantification methods have been proposed in AE technique, not all have achieved universal approval or have been approved as suitable for all situations. The b-value analysis, which involves the study of distribution of amplitudes of AE signals, and its modified form (known as improved b-value analysis), was investigated for suitability for damage quantification purposes in ductile materials such as steel. This was found to give encouraging results for analysis of data from laboratory, thereby extending the possibility of its use for real life structures.
By addressing these primary issues, it is believed that this thesis has helped improve the effectiveness of AE technique for structural health monitoring of civil infrastructures such as bridges.
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Byers, Russell F. Carleton University Dissertation Engineering Electrical. "Modification of short-time fourier transformed speech magnitude using image filter operators." Ottawa, 1991.
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Kerbal, Sofiane. "Development of new criteria for train detection and evaluation in critical conditions." Thesis, KTH, Skolan för elektroteknik och datavetenskap (EECS), 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-253201.
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Railway signaling is of paramount importance to ensure traffic management andsafety on the rail network. The main lines are divided into sections called ‘blocks’,which are governed by a fixed signal installation. To prevent trains from colliding,each block allows one train at once. In France (and most European countries),train detection is performed by an electrical device called track circuit that consistsof a transmitter and a receiver installed at the track-side, and connected via therails. In the absence of a train, an electrical signal flows from the transmitter tothe receiver through the rails. As a train enters a track circuit, its axles shuntthe rails, provoking a short circuit (also called ‘shunt’): the signal transmitted tothe receiver drops. The detection of that signal drop results in the detection of atrain. This method rarely fails throughout the network, but there can be criticalcases where it may be inefficient. In this Master’s Thesis, new detection criteriaproposed in previous studies have been tested on signals measured in poor shuntingconditions. Three approaches have been tested: one in the time domain and two inthe frequency domain. The time approach compares the short-term and long-termstatistics of the received signals. The observation of a change in the spectra of thereceived signals around the 3rd order harmonic (3OH) has led to the implementationof two frequency criteria: the estimation of the band power around the 3OH andthe detection of the 3OH peaks. The obtained results show that better detection isachieved when the new criteria and the existing one are combined.Tågsignalsystem är väsentliga för att garantera trafikstyrning och säkerhet i tågnätet.Spåren är indelade i sektioner, s.k. block, som övervakas med fasta signalinstallationer.För att hindra tåg från att krocka, tillåts bara ett tåg i taget per block. IFrankrike (och de flesta andra europeiska länder), detekteras tågen med en elektriskspårkrets som består av en sändare och en mottagare som är installerad bredvidspåret och ansluten till rälsen. När inget tåg finns på spåret, flyter en elektrisk signalfrån sändaren till mottagaren via spåret. När ett tåg anländer, kortsluts kretsenav hjulaxeln och signalen försvinner från mottagaren. Minskningen i signalstyrkaanvänds för att detektera tåget. Denna metod sällan misslyckas i tågnätet, men iovanliga fall kan det uppstå farliga situationer. I detta examensarbete utvärderasnya detektionsmetoder, som har föreslagits i tidigare studier, på signaler som haruppmätts under förhållanden med dålig kontakt mellan hjul och spår. Tre olika metoderhar testats, en i tidsdomänen och två i frekvensdomänen. Tidsdomänsmetodenjämför kortvarig och långvarig statistik för den mottagna signalen. I spektrum förden mottagna signalen, har man observerat en förändring runt den tredje övertonen,samt detektering av frekvenstoppar vid tredje övertonen. De erhållna resultatenvisar på förbättrad detektering när de nya och existerande kriterierna kombineras.
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Hertzog, P. E., and G. D. Jordaan. "Wavelets and short time fourier transforms on ultrasonic doppler signals for pregnancy determination in sheep." Interim : Interdisciplinary Journal, Vol 5, Issue 1: Bloemfontein : Central University of Technology, Free State, 2006. http://hdl.handle.net/11462/414.
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Published ArticleThe reproductive status of animals is of utmost importance to the modern farmer. Decisions concerning the management of the flock are influenced by the knowledge of the percentage of animals that are pregnant at any specific time. The aim of the project was to gain knowledge for the development of an instrument that is affordable and with which a farmer can do pregnancy determination himself/herself, thereby enabling him/her to make the correct management decisions. Experimental data were obtained from pregnant Dorper ewes with the aid of a portable Doppler instrument. Using real data as input, simulations of Wavelet and Short Time Fourier Transforms (STF) were done in MathCAD. In the simulations known levels of noise were added to the Doppler signals. Satisfactory results were obtained from the simulations of Wavelet Transforms. In the simulation of the Wavelet Transforms, signals with a SNR of -6.5 dB were successfully identified. It can thus be concluded that Wavelet Transforms can be used successfully for the detection of the fetal heartbeat in noisy ultrasonic Doppler signals.
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Kubišta, Ladislav. "Mikrofonní pole malých rozměrů pro odhad směru přicházejícího zvuku." Master's thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2020. http://www.nusl.cz/ntk/nusl-413257.
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This thesis describe detection of direction receiving sound with small–size microphone array. Work is based on analyzing methods of time delay estimation, energy decay or phase difference signal. Work focus mainly on finding of angle of arrival in small time difference. Results of measuring, as programming sound, so sound recorded in laboratory conditions and real enviroment, are mentioned in conclusion. All calculations were done by platform Matlab
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Hanzálek, Pavel. "Praktické ukázky zpracování signálů." Master's thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2019. http://www.nusl.cz/ntk/nusl-400849.
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The thesis focuses on the issue of signal processing. Using practical examples, it tries to show the use of individual signal processing operations from a practical point of view. For each of the selected signal processing operations, an application is created in MATLAB, including a graphical interface for easier operation. The division of the thesis is such that each chapter is first analyzed from a theoretical point of view, then it is shown using a practical demonstration of what the operation is used in practice. Individual applications are described here, mainly in terms of how they are handled and their possible results. The results of the practical part are presented in the attachment of the thesis.
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Lin, Chien-Ying, and 林謙盈. "The Study of Hopping Short Time Fourier Transform." Thesis, 2015. http://ndltd.ncl.edu.tw/handle/45484541282306465188.
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碩士國立臺北大學
通訊工程研究所
103
In the signal processing, we usually use Fourier transform the signal from time domain to frequency domain to analyze frequency. Before this study, Fourier transform already have some algorithm ex: Short time Fourier transform (STFT) and fast Fourier transform (FFT). Usually when we compute the Fourier transform, we will hop some time interval and compute the signal again. It will waste lots of resource during recomputing. In this study, we propose three efficient method of computing the hopping short-time Fourier transform (HSTFT). The idea is using the iterative equation to reduce the computation and prove the error is bounded. These three methods have different pros and cons to apply in different condition. Among the algorithms, FFT can only analyze the frequency which is an integer multiple of 2π/N but FFT just need less computation; STFT can analyze arbitrary frequency but have greater computational complexity. We will discuss these issues in the study.
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Lai, Hsin-Liang, and 賴信良. "Mixed signal separation based on fractional Fourier and short-time Fourier transform analysis." Thesis, 2014. http://ndltd.ncl.edu.tw/handle/d74x7z.
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碩士國立雲林科技大學
電機工程系
102
In this thesis, the methods for mixed signal separation based on fractional Fourier and short-time Fourier transform analysis are proposed. In the first part, we determine the best order of fractional Fourier transform for separating the mixed signals in a theoretical approach. Then, the results based on the Gaussian fitting approach reported in our previous work are validated. In the second part, consider that the multi-component Gaussian linear chirp signals may overlap in a single fractional order. The separated signals may have low correlation coefficients with their original versions. Because the spectrogram of a Gaussian linear chirp signal is elliptically distributed, we use a simplex downhill search method to obtain the spectral distribution of each signal and reconstructed the signal using the short time inverse Fourier transform. In the third part, we analyze the best order of fractional Fourier transform of the circular fringe pattern in a theoretical approach. We propose an iterative approach to search for the best fractional order by recording the maximum projection of fractional Fourier transform of signals. Then we search for the best order with a local maximum through a differential operation, and find center point of the circular fringe pattern by using the spatial filtering process. The results show that the parameters of reconstructed circular fringe pattern are close to that of the original one.
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Lei, Ieok-Pan, and 李躍斌. "Addendum of Missing Groundwater Levels data Using Short-Time Fourier Transform." Thesis, 2016. http://ndltd.ncl.edu.tw/handle/2yjx7d.
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碩士國立交通大學
土木工程系所
105
Groundwater plays an important role on regional water supply, and observation wells are critical for groundwater related analysis and management. In Taiwan, a national wise groundwater observation network was completed in 2008 and a huge amount of groundwater levels data were collected. However, because of the uncertainty of data collecting instruments and wells maintenance, data miss is unavoidable. To addendum the missing groundwater levels data, this study developed a novel data addendum procedure based on the Linear Regression (LR) and Short-Time Fourier Transform (STFT). The proposed novel procedure can preserve the data features in time domain and frequency domain. The proposed method consists of three steps. The first step is to estimate the missing daily data by using a LR model based on the neighboring well data that has the highest correlation with the well data to be addendum. The process was expected to preserve the low frequency variation of the groundwater table below 1 cycle/week. The second step is to transform the time series data to be addendum into frequency domain via STFT. The resulting spectrum will have missing segment due to the missing data. The third step is to completed the spectrum and obtains the complete groundwater level data. To addendum the spectrum, the missing spectral segment was recovered by jointing the low frequency portion of the interpolated daily data and the high frequency part of the original data to be addendum. The complete groundwater level data was obtained by using Inversed STFT to the addendum spectrum. The proposed methodology was applied to addendum the groundwater levels data in northern part of Chianan Plain and the result shows that the addendum data can effectively preserve the data features in both time domain and frequency domain. The methodology can be applied to addendum other hydrological time series data to allow the application of data driven analysis.
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Tsao, Chieh-Yu, and 曹介羽. "Repeat Regions Detection of DNA Sequences by Short Time Fourier Transform." Thesis, 2007. http://ndltd.ncl.edu.tw/handle/74485163299505650062.
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碩士國立臺灣海洋大學
通訊與導航工程系
95
Abstract Stimulated by the biotechnology revolution and the achievement of the Human Genome Project, the analysis of DNA sequence is more and more interesting and attracting. And finding repetitive sequences in DNA is of particular interest in biology due to their role in genetic diseases, human gene mapping, evolution, and many other important and interesting applications. In the face of such a question, it is urgent and far challenging to develop approaches to analyze the complex biological functions of DNA repeated sequence. For DNA sequences analysis, it is of great importance to find the position of DNA repeated sequences. The main purpose of this thesis is to develop efficient algorithms based on digital signal processing techniques such as the DFT, STFT, and Dot-matrix to find the DNA repeated sequences. At the first, structure and fundamental characteristic of the repeat sequence will be introduced. The main characteristic frequency which is the reciprocal of the repeated pattern length will be derived by the FFT. The main characteristic frequency will be incorporated into the short-time Fourier transform such that the repeated sequence locations can be clearly identified as distinct peaks (or colors) in the spectrum. Then a mixed method based on dot-matrix and auto-correlation algorithms will be employed to detect the repeat of the DNA sequences. Furthermore, we adopt the modified particle swarm optimization (MPSO) algorithm to look for the repeated regions of the DNA sequence. The method has a pretty good result to inter-spread repeat sequence. Finally, we take some datasets from the National Center for Biotechnology Information (NCBI) for illustrating the effectiveness of the proposed algorithms.
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FANG, ZHEN-HONG, and 方振鴻. "Signal analysis by short-time fourier transform and pseudo wigner distribution." Thesis, 1989. http://ndltd.ncl.edu.tw/handle/45034471683607392574.
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JONES, DOUGLAS LLEWELLYN. "A STUDY OF WINDOWS FOR THE SHORT-TIME FOURIER TRANSFORM (WIGNER, TIME, FREQUENCY, MATCHED)." Thesis, 1986. http://hdl.handle.net/1911/13170.
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Wei, Chih-Chao, and 魏志兆. "Automatic Heart Sound Analysis with Short-Time Fourier Transform and Support Vector Machines." Thesis, 2009. http://ndltd.ncl.edu.tw/handle/fg63w3.
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碩士國立臺灣師範大學
應用電子科技研究所
97
The heart disease has become the second cause of death, and most of heart diseases result from heart valve disorders. skilled cardiologists probe heart sounds by electronic stethoscope through human ears, but interpretation of heart sounds is a very special skill which is quite difficult to teach in a structured way. Because of this reason, automatic heart sound analysis in computer systems would be very helpful for medical staff. This paper presents a complete heart sound analysis system covering from the segmentation of beat cycles to the final determination of heart conditions. The kernels of heart beat cycle segmentation and recognition are based on autocorrelation, short-time Fourier transform, and support vector machines. The experiments are done with a public heart sound database released by Texas Heart Institute, with very promising recognition rate achieved.
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LI, MENG-SIAN, and 李孟賢. "Study and Analysis of Short-Time Fourier Transform for Differential Frequency Hopping Sequences." Thesis, 2010. http://ndltd.ncl.edu.tw/handle/65130131616363058393.
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碩士中華科技大學
電子工程研究所碩士班
98
DFH (differential frequency hopping, DFH) communications system is to use frequency hopping, and its relevance to carry around like to send the data bits. Comparison of the system include the frequency shift key technology design G function, frequency detection, and received a series detect the state of the path. In this paper, the frequency detected by the receiver-side short-time Fourier transform (STFT) frequency hopping sequence detection technology as the basis of frequency hopping signals to do the original analysis to confirm the correctness of system design; to make further additive white Gaussian noise (AWGN), multipath effects, fading channel (fading channel) and other environmental, all simulation data under the situation of frequency detection and data recovery. In this paper the design of the detection process in the final simulation results show, STFT in AWGN, multipath ISI (inter symbol interference, ISI) and fading channels can really under the influence of the frequency of screening in the first phase will be transmitter sent by the frequency selected. However, the simulation found that the information system restore point the real difficulty is to STFT, the frequency of the selected sequence to be screened; with the transfer matrix of the screening method, if want to have good performance, in fact, there are many conditions or factors that are closely linked with the transfer matrix structure; such as the size of transfer matrix, fan-out state of the matrix coefficients, these parameters will be using transfer matrix G frequency filter function caused by a misjudgment.
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Lo, Fang-Chun, and 羅芳鈞. "Application of Short-Time Fourier Transform for Real-Time Surface Damage Detection of Wind Turbine Blades." Thesis, 2017. http://ndltd.ncl.edu.tw/handle/tgpw7x.
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碩士國立臺灣大學
工程科學及海洋工程學研究所
105
The main idea of this research is to establish a complete system for surface damage detection of wind turbine blades. Because of long-term exposure in an extreme environment, the damage on wind turbine’s components is inevitable, and mostly on the blades. Thus, wind turbine requires regular detection and maintenance to avoid safety issues and financial loses. The traditional assessment for surface damage detection of wind turbine blades is to evaluate the operation noise by a professional using his ears to listen. Sometimes, judging by the professional’s personal experience, he has to stop the wind turbine and execute the detection from the above to the blades. Not only does it demand special skills, it is also accompanied with high risk caused by the extreme environment wind turbine was built at. So, it is very dangerous and inconvenient for us if we must count on ears or climbing skills to conduct the assessment, not to mention the recent arising of offshore wind turbine. With the number of global wind turbine rapidly increases and develops, establishing a complete system for surface damage detection of wind turbine blades becomes more and more essential. This research using time-frequency analysis short-time Fourier transform from MATLAB to analyze the blades’ noise while operation, by placing microphone under the wind turbine and recording. First, to build a normal model as foundation for comparison, we put recordings of a wind turbine without abnormal sound into time-frequency analysis and applying it to methods like marginal spectrum, decibel transformation and polynomial regression. Then, based on the normal model, we defined the formula this research shows, as an indicator to determine if the blades are damaged. Finally, we can also define the optimal damage threshold by utilizing the receiver operating characteristic curve and calculating the area under the curve. This new way for detection allows us to receive blades’ damage reports by computer’s automatically diagnosis without affecting or stopping the wind turbine’s operation. This research’s detection results are testified by actual photo from wind turbine’s blades. Hopefully, it can be applied as wind turbine’s health detection systems in the future.
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RIBA, LUIGI. "Multi-Dimensional Stockwell Transforms and Applications." Doctoral thesis, 2014. http://hdl.handle.net/2318/142144.
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Liao, Chien-Cheng, and 廖乾丞. "Application of Short Time Fourier Transform for Improving the FTP Phase Recovery in case of Local Large Phase Gradient." Thesis, 2016. http://ndltd.ncl.edu.tw/handle/rxge2r.
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碩士國立中興大學
機械工程學系所
104
The propose of this paper is solving the problem that we can’t extract the precise phase at the high phase gradient when using the traditional Fringe Pattern Profilometry (FPP) and Fourier Transform Profilometry (FTP).With the idea of the Short Time Fourier Transform (STFT), we can find the partial frequency of the fringe in the original, messy spectrum. Using the inverse mapping, the original, deform fringe-pattern could be translated to the relative phase of the reference plane according to the phase of the first filtering. After the inverse mapping, we can use the Papoulis-Gerchberg algorithm to fill the areas which have no data, so it would help us to examine the precise which are found of the filtering in the frequency domain. If the data is not complete, we could reduce the analysis window which is used in the STFT. Keep repeating this step, until the precise which are modulated by the contour of the surface are eliminated. The experimental results display the precise which are modulated by the contour of the surface of the high fringe-diversification in the traditional FTP could be find and restore successfully by using the inverse mapping and the P-G algorithm to search the position of the filtering repeatedly.