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Transformationen

Fourier-, Chirp-Z-, DCT-, Hilbert-, Cepstrum-, Walsh-Hadamard-Transformation

Signal Processing Toolbox™ stellt Funktionen bereit, mit denen Sie häufig verwendete Vorwärts- und Rückwärtstransformationen berechnen können, darunter die schnelle Fourier-Transformation (FFT), die diskrete Kosinustransformation (DCT) und die Walsh-Hadamard-Transformation. Extrahieren Sie die Signalhüllkurven und schätzen Sie die Momentanfrequenzen mithilfe des analytischen Signals. Signale im Zeit-Frequenz-Bereich analysieren. Untersuchen Sie Amplituden-Phasen-Beziehungen, schätzen Sie Grundfrequenzen und erkennen Sie spektrale Periodizität mithilfe des Cepstrums. Berechnen Sie diskrete Fourier-Transformationen mit Hilfe des Goertzel-Algorithmus zweiter Ordnung.

Funktionen

alle erweitern

Diskrete Fourier- und Kosinustransformationen

`abs`	Absoluter Wert und komplexer Betrag
`angle`	Phasenwinkel
`fft`	Schnelle Fourier-Transformation
`ifft`	Inverse fast Fourier transform
`fftshift`	Verschieben der Nullfrequenz-Komponente zur Mitte des Spektrums
`ifftshift`	Inverse zero-frequency shift
`dftmtx`	Discrete Fourier transform matrix
`fft2`	2-D fast Fourier transform
`ifft2`	2-D inverse fast Fourier transform
`instfreq`	Estimate instantaneous frequency
`czt`	Chirp Z-transform
`goertzel`	Discrete-Time Fourier transform with second-order Goertzel algorithm
`dct`	Discrete cosine transform
`idct`	Inverse discrete cosine transform

Hilbert- und Walsh-Hadamard-Transformationen

`envelope`	Signal envelope
`fwht`	Fast Walsh-Hadamard transform
`ifwht`	Inverse Fast Walsh-Hadamard transform
`hilbert`	Discrete-time analytic signal using Hilbert transform

Zeit-Frequenz-Analyse

`emd`	Empirical mode decomposition
`fsst`	Fourier synchrosqueezed transform
`ifsst`	Inverse Fourier synchrosqueezed transform
`hht`	Hilbert-Huang transform
`pspectrum`	Analyze signals in the frequency and time-frequency domains
`spectrogram`	Spectrogram using short-time Fourier transform
`xspectrogram`	Cross-spectrogram using short-time Fourier transforms
`stft`	Short-time Fourier transform
`dlstft`	Deep learning short-time Fourier transform (Seit R2021a)
`stftLayer`	Short-time Fourier transform layer (Seit R2021b)
`istftLayer`	Inverse short-time Fourier transform layer (Seit R2024a)
`stftmag2sig`	Signal reconstruction from STFT magnitude
`istft`	Inverse short-time Fourier transform
`dlistft`	Deep learning inverse short-time Fourier transform (Seit R2024a)
`vmd`	Variational mode decomposition
`wvd`	Wigner-Ville distribution and smoothed pseudo Wigner-Ville distribution
`xwvd`	Cross Wigner-Ville distribution and cross smoothed pseudo Wigner-Ville distribution

Cepstralanalyse

`cceps`	Complex cepstral analysis
`icceps`	Inverse complex cepstrum
`rceps`	Real cepstrum and minimum-phase reconstruction

Bitumkehr

`bitrevorder`	Permute data into bit-reversed order
`digitrevorder`	Permute input into digit-reversed order

Themen

Diskrete Fourier- und Kosinustransformationen

Discrete Fourier Transform
Explore the primary tool of digital signal processing.
Chirp Z-Transform
Use the CZT to evaluate the Z-transform outside of the unit circle and to compute transforms of prime length.
Discrete Cosine Transform
Compute discrete cosine transforms and learn about their energy compaction properties.
DCT for Speech Signal Compression
Use the discrete cosine transform to compress speech signals.

Hilbert- und Walsh-Hadamard-Transformationen

Hilbert Transform
The Hilbert transform helps form the analytic signal.
Analytic Signal for Cosine
Determine the analytic signal for a cosine and verify its properties.
Envelope Extraction
Extract the envelope of a signal using the hilbert and envelope functions.
Analytic Signal and Hilbert Transform
Generate the analytic signal for a finite block of data using the hilbert function and an FIR Hilbert transformer.
Hilbert Transform and Instantaneous Frequency
Estimate the instantaneous frequency of a monocomponent signal using the Hilbert transform. Show that the procedure does not work for multicomponent signals.
Single-Sideband Amplitude Modulation
Perform single-sideband amplitude modulation of a signal using the Hilbert transform. Single-sideband AM signals have less bandwidth than normal AM signals.
Walsh-Hadamard Transform
Learn about the Walsh-Hadamard transform, a non-sinusoidal, orthogonal transformation technique.
Walsh-Hadamard Transform for Spectral Analysis and Compression of ECG Signals
Use an electrocardiogram signal to illustrate the Walsh-Hadamard transform.

Cepstralanalyse

Complex Cepstrum — Fundamental Frequency Estimation
Use the complex cepstrum to estimate a speaker’s fundamental frequency. Compare the result with the estimate obtained with a zero-crossing method.
Cepstrum Analysis
Apply the complex cepstrum to detect echo in a signal.