STFT Short time Fourier transform Or windowed Fourier
- Slides: 61
STFT (Short time Fourier transform) Or windowed Fourier transform
This is the basis for most computer generated spectrograms (display pixel intensity on a log scale by limiting the dynamic range to about 60 -80 d. B).
Ejemplos de espectrogramas Here is the sum of two parallel linear chirps with its spectrogram.
Here is the sum of two hyperbolic chirps and its spectrogram.
Introducción a Wavelets
four frequency components at different times. The interval 0 to 250 ms is a sinusoid of 300 Hz, and the other 250 ms intervals are sinusoids of 200 Hz, 100 Hz, and 50 Hz w(t)=exp(-a*(t^2)/2)
Wavelet de Morlet
The mexican hat wavelet
Gráficos de varios tipos distintos de wavelets. (a) Wavelet de Haar, (b) Wavelet de Daubechies, (c) Wavelet de Morlet. (Cortesía de Ofer Levi, Universidad de Stanford)
Escala
(CWT) Continuous Wavelet Transform ¨escalograma¨ These signals are drawn from a database signals that includes event related potentials of normal people, and patients with Alzheimer's disease.
En un espectrograma:
En un escalograma:
Suma de dos señales CHIRP hiperbólicas Windowed fourier transform (Espectrograma) Continuous Wavelet Transform CWT (Escalograma)
Representación frecuencia-tiempo para: (a) Datos muestreados (b) FT (c) WFT (d) CWT
MATLAB “cwt” COEFS = cwt(S, SCALES, 'wname') computes the continuous wavelet coefficients of the vector S at real, positive SCALES, using the wavelet whose name is 'wname'
DWT (Discrete Wavelet Transform)
Ahora dejamos fija la Ondeleta y lo que vamos comprimiendo por etapas es la señal
El análisis multiresolución se consigue a través de filtrado y submuestreo de la señal original. n La exploración en tiempo se consigue a través de operaciones de convolución (filtrado digital). n
Sub-band coding
Sub-band coding algorithm
Transformada inversa
2 -D Discrete Wavelet Transform
Wavelet Packet
En resumen: CWT DWT 2 D - DWT
. . . En resumen: CWT DWT 2 D - DWT
n http: //www. gisdevelopment. net/techn ology/ic/techip 0003 a. htm COMPRESION DE LA DCT A WAVELETS http: //www. acm. org/crossroads/xrds 6 -3/sahaimgcoding. html#Fig 6
- Windowed fourier transform
- Short short short long long long short short short
- Stft
- Short time fft
- Reverse image search
- Ct ft
- Time shift fourier transform
- Dtft symmetry property
- Sinc fourier transform
- Fourier transform of dirac delta function proof
- Dft table
- Parseval's identity for fourier transform
- Fourier transform properties table
- Line spectrum in signals and systems
- Phase meaning
- Inverse discrete fourier transform
- Matlab ramp function
- Frequency
- Fourier transform properties solved examples
- Fourier transform of unit step function
- Difference of gaussian filter
- Fourier transform
- Fourier image processing
- Properties of fourier transform
- The fourier transform and its applications
- Inverse fourier transform
- Fourier transform
- Polar fft
- Fourier transform of product of two functions
- Comb function matlab
- Sinc fourier transform
- Impulse train fourier transform
- Discrete fourier transform
- Fourier transform of impulse train
- Fourier transform of circ function
- Fourier transform of sinc
- Fourier transform is defined for
- Fourier series formulas
- Parseval's theorem
- Fourier transform table
- Cosine integral
- Duality of fourier transform
- Series de fourier
- Fourier transform
- Integral of unit step function
- Relationship between laplace and fourier transform
- R fft
- Fourier transform solver
- How to find the fourier series of a periodic function
- Dit fft algorithm
- Dft
- Fftshift
- Chirped pulse fourier transform microwave spectroscopy
- Fourier transform of shifted rectangular pulse
- Dft
- Sine integral
- Fft integer multiplication
- Fourier transform of reciprocal function
- Inverse of fourier transform
- Fractional fourier transform
- Fourier transform definition
- Application of discrete fourier transform