Transforms
DSP System Toolbox™ offers several System objects and blocks to transform streaming time-domain signals into frequency domain, and vice versa. Techniques such as fast Fourier transform (FFT), short-time Fourier transform, high-resolution FFT, wavelet transforms, and the corresponding inverse operations enable you to analyze the signal in either of the domains and have applications in several fields. For an example, see Analyze a Subband of Input Frequencies Using Zoom FFT. For a MathWorks® teaching curriculum module on this topic, see Fourier Analysis (MathWorks Teaching Resources).
DSP System Toolbox also offers the Wavelet Scattering block, which creates a framework for wavelet time scattering in the Simulink® environment. Use this block to derive low-variance features from real-valued data, and then use those features in machine learning and deep learning applications. For more information, see Wavelet Scattering (Wavelet Toolbox). The Wavelet Scattering block requires Wavelet Toolbox™.
Objects
| 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 | 
Blocks
Topics
- Transform Time-Domain Data into Frequency DomainThis example shows how to transform time-domain data into the frequency domain using the FFT block. 
- Transform Frequency-Domain Data into Time DomainWhen you want to transform frequency-domain data into the time domain, use the IFFT block. 
- Linear and Bit-Reversed Output OrderLearn 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 FFTCompute the zoom FFT of a sine wave in Simulink. 
- Speech Enhancement with Gain in Frequency DomainDenoise 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 ObjectsList of System objects that support variable-sized signals in DSP System Toolbox. 



