introduction: an efficient method of tomographic imaging in nuclear medicine is positron emission tomography (pet). compared to spect, pet has the advantages of higher levels of sensitivity, spatial resolution and more accurate quantification. however, high noise levels in the image limit its diagnostic utility. noise removal in nuclear medicine is traditionally based on fourier decomposition o...

We study the connection between STFT multipliers A1⊗mg1,g2 having windows g1,g2, symbols a(x,ω)=(1⊗m)(x,ω)=m(ω), (x,ω)∈R2d, and Fourier Tm2 with symbol m2 on Rd. find sufficient necessary conditions m,m2 g1,g2 for equality Tm2=A1⊗mg1,g2. For m=m2 former holds only particular choices of window functions in modulation spaces, whereas it never occurs realm Lebesgue spaces. In general, multiplier A...

Development of robust and efficient front-end is crucial for robust ASR. Proper time and frequency resolution of the TFR of speech, motivated by the auditory models is considered an important factor for robustness. An efficient method of realizing a variable resolution TFR using DTFT/Goertzel algorithm is proposed instead of the standard FFT based approach. It is shown that the new representati...

In this paper, we examine the theory of motion-free superresolution by formulating the problem in the Discrete Time Fourier Transform (DTFT) and the Discrete Fourier Transform (DFT) domain. Our approach provides some new insights into how aliasing and blurring can effect exact reconstruction of the superresolved image. For ease of understanding, the analysis, is initially carried out in the 1-D...

The classical method of numerically computing the Fourier transform of digitizedfunctions in one or in ddimensions is the so-called discrete Fourier transform ( D F T ) , efficiently implemented as Fast Fourier Transform ( F F T ) algorithms. In m n y cases the D F T is not an adequate appmximation of the continuous Fourier transform. The method presented in this contribution provides accurate ...

Traditional Fast Fourier Transform algorithm makes the implementation of the multicarrier system feasible and attractive with respect to single-carrier systems. However, when the channel is doubly selective (i.e. time-frequencyselective), this traditional methodology fails. Since the channel frequency response is rapidly time-varying as a result the optimal transmission/reception methodology no...

We study the windowed Fourier transform in the framework of Clifford analysis, which we call the Clifford windowed Fourier transform (CWFT). Based on the spectral representation of the Clifford Fourier transform (CFT), we derive several important properties such as shift, modulation, reconstruction formula, orthogonality relation, isometry, and reproducing kernel. We also present an example to ...

Time-frequency distributions (TFDs) have proven useful in a wide variety of nonstationary signal processing applications. While sophisticated optimal bilinear TFDs have been developed to extract the maximum possible timefrequency information from signals, certain applications dictate simpler linear, running-FFT processing techniques. In this paper, we propose a signal-dependent short-time Fouri...