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Trasformate

Trasformate di Fourier, trasformate del coseno e wavelet, dispersione wavelet

DSP System Toolbox™ offre diversi System object e blocchi per trasformare i segnali di streaming nel dominio del tempo in segnali nel dominio della frequenza e viceversa. Tecniche come la trasformata di Fourier veloce (FFT), la trasformata di Fourier a tempo breve, la FFT ad alta risoluzione, le trasformate wavelet e le corrispondenti operazioni inverse consentono di analizzare il segnale in uno dei due domini e trovano applicazione in diversi campi. Per un esempio, vedere Analyze a Subband of Input Frequencies Using Zoom FFT. Per un modulo didattico MathWorks^® su questo argomento, vedere Analisi di Fourier (Risorse didattiche MathWorks).

DSP System Toolbox offre inoltre il blocco Wavelet Scattering che crea un framework per la dispersione temporale wavelet nell'ambiente di Simulink^®. Utilizzare questo blocco per ricavare feature a bassa varianza da dati a valore reale e utilizzare tali feature in applicazioni di Machine Learning e Deep Learning. Per ulteriori informazioni, vedere Wavelet Scattering (Wavelet Toolbox). Il blocco Wavelet Scattering richiede Wavelet Toolbox™.

Oggetti

`dsp.FFT`	Discrete Fourier transform
`dsp.IFFT`	Inverse discrete Fourier transform (IDFT)
`dsp.ISTFT`	Inverse short-time FFT
`dsp.STFT`	Short-time FFT
`dsp.ZoomFFT`	High-resolution FFT of a portion of a spectrum

Blocchi

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Trasformate di Fourier

Complex Cepstrum	Compute complex cepstrum of input
FFT	Fast Fourier transform (FFT) of input
IFFT	Inverse fast Fourier transform (IFFT) of input
Inverse Short-Time FFT	Recover time-domain signals by performing inverse short-time fast Fourier transform (FFT)
Magnitude FFT	Compute nonparametric estimate of spectrum using periodogram method
Real Cepstrum	Compute real cepstrum of input
Short-Time FFT	Nonparametric estimate of spectrum using short-time fast Fourier transform (STFT) method
Zoom FFT	High-resolution FFT of a portion of a spectrum

Trasformate del coseno e wavelet

DCT	Discrete cosine transform (DCT) of input
DWT	Compute discrete wavelet transform (DWT) of input or decompose signals into subbands with smaller bandwidths and slower sample rates
IDCT	Inverse discrete cosine transform (IDCT) of input
IDWT	Inverse discrete wavelet transform (IDWT) of input or reconstruct signals from subbands with smaller bandwidths and slower sample rates
Wavelet Scattering	Model wavelet scattering network in Simulink (Da R2022b)

Argomenti

Transform Time-Domain Data into Frequency Domain
This example shows how to transform time-domain data into the frequency domain using the FFT block.
Transform Frequency-Domain Data into Time Domain
When you want to transform frequency-domain data into the time domain, use the IFFT block.
Linear and Bit-Reversed Output Order
Learn the meaning of linear and bit-reversed data order as used by the FFT and IFFT blocks.
Analyze a Subband of Input Frequencies Using Zoom FFT
Compute the zoom FFT of a sine wave in Simulink.
Speech Enhancement with Gain in Frequency Domain
Denoise a signal by applying selective gain on the signal in the frequency domain. Convert the denoised signal back into time domain and play the signal using Audio Device Writer.
Variable-Size Signal Support DSP System Objects
List of System objects that support variable-sized signals in DSP System Toolbox.

Informazioni complementari

Analisi di Fourier (Risorse didattiche MathWorks)

Esempi in primo piano

Zoom FFT

Showcases zoom FFT, which is a signal processing technique used to analyze a portion of a spectrum at a high resolution. DSP System Toolbox™ offers this functionality in MATLAB® through the dsp.ZoomFFT System object™, and in Simulink® through the Zoom FFT block in the DSP System Toolbox library.

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Detect Air Compressor Sounds in Simulink Using Wavelet Scattering

Use the Wavelet Scattering block and a pretrained deep learning network to classify audio signals.

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Detect Anomalies in ECG Data Using Wavelet Scattering and LSTM Autoencoder in Simulink

Use wavelet scattering and deep learning network to detect anomalies in ECG signals.

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