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...

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...

during the last two decades, maximum likelihood estimation (ml) has been used to determine direction of arrival (doa) and signals propagated by the sources, using narrowband array signals. the algorithm fails in the case of wideband signals. as an attempt by the present study to overcome the problem, the array outputs are transformed into narrowband frequency bins, using short time fourier tran...

the purpose of the current research is investigating the phenylalanine removal by using magnetic nanoparticles (fe3o4) from water samples. the effect of ph, contact time and phenylalanine concentration on phenylalanine adsorption efficiency by magnetite nanoparticles are studied in a batch system. transmission electron microscopy (tem), x-ray diffraction patterns (xrd) and fourier transform inf...

An algorithm for efficient and accurate computation of the fractional Fourier transform is given. For signals with time-bandwidth product N , the presented algorithm computes the fractional transform in O( N log N ) time. A definition for the discrete fractional Fourier transform that emerges from our analysis is also discussed.

An algorithm for efficient and accurate computation of the fractional Fourier transform is given. For signals with time-bandwidth product N , the presented algorithm computes the fractional transform in O( N log N ) time. A definition for the discrete fractional Fourier transform that emerges from our analysis is also discussed.

Uncertainty principles for functions defined on finite Abelian groups generally relate the cardinality of a function to the cardinality of its Fourier transform. We examine how the cardinality of a function is related to the cardinality of its short–time Fourier transform. We illustrate that for some cyclic groups of small order, both, the Fourier and the short–time Fourier case, show a remarka...

Shift and rotation invariance properties of linear time-frequency representations are investigated. It is shown that among all linear time-frequency representations, only the short-time Fourier transform (STFT) family with the Hermite–Gaussian kernels satisfies both the shift invariance and rotation invariance properties that are satisfied by the Wigner distribution (WD). By extending the time-...

The offset linear canonical transform (OLCT) is the name of a parameterized continuum of transforms which include, as particular cases, the most widely used linear transforms in engineering such as the Fourier transform (FT), fractional Fourier transform (FRFT), Fresnel transform (FRST), frequency modulation, time shifting, time scaling, chirping and others. Therefore the OLCT provides a unifie...

The Fourier transform is often used to connect the Lorentzian energy distribution for resonance scattering to the exponential time dependence for decaying states. However, to apply the Fourier transform, one has to bend the rules of standard quantum mechanics; the Lorentzian energy distribution must be extended to the full real axis −∞ < E < ∞ instead of being bounded from below 0 ≤ E < ∞ (“Fer...