This paper is concerned with a synthesis study of the fast Fourier transform (FFT), the short time Fourier transform (STFT and the Wigner distribution (WD) in analysing the phonocardiogram signal (PCG) or heart cardiac sounds.     The FFT (Fast Fourier Transform) can provide a basic understanding of the frequency contents of the heart sounds. The STFT is obtained by calculating the Fourier tran...

The windowed Fourier transform of a time signal is considered, as well as a way to reconstruct the signal from a su ciently densely sampled version of its windowed Fourier transform using a Gabor representation; followingGabor, sampling occurs on a two-dimensional time-frequency lattice with equidistant time intervals and equidistant frequency intervals. In the limit of innitely dense sampling,...

By use of window functions, time-frequency analysis tools like Short Time Fourier Transform overcome a shortcoming of the Fourier Transform and enable us to study the timefrequency characteristics of signals which exhibit transient oscillatory behavior. Since the resulting representations depend on the choice of the window functions, it is important to know how they influence the analyses. One ...

This letter addresses the coherent integration problem for detecting high-speed target. A fast method based on short-time Fourier transform (STFT) and sequence reversing (SRT), that is, STFT-SRT, is proposed. In this method, STFT first employed to obtain velocity improve SNR without additional calculation. After that, SRT presented remove range migration (RM). Finally, (FT) conducted achieve in...

A time-frequency analysis, which represents the time change of a signal, is significant in all fields. Wigner distribution, a short time Fourier transform (STFT), a kernel method, and a characteristic function method etc. are known as a time-frequency analyzing method, and those methods have merits and demerits. STFT method has been used as ultrasound blood-flow imaging for a long time, because...

in this paper, we propose a new residual analysis method using fourier series transform into fuzzy time series model for improving the forecasting performance. this hybrid model takes advantage of the high predictable power of fuzzy time series model and fourier series transform to fit the estimated residuals into frequency spectra, select the low-frequency terms, filter out high-frequency term...

There are two methods for identifying formation interface in oil wells: core analysis, which is a precise approach but costly and time consuming, and well logs analysis, which petrophysists perform, which is subjective and not completely reliable. In this paper, a novel coupled method was proposed to detect the formation interfaces using GR logs. Second approximation level (a2) of GR log gained...

We present a theor of linear and quadratic time-frequency representations (&FRs) that are covariant to time-frequency displacement operators. The theory unifies important T F R classes (short-time Fourier transform, wavelet transform; Cohen’s, affine, hyperbolic, and power classes), and it allows the systematic construction of new TFRs that are covariant to a given operator.