This version (09 Jul 2019 08:12) was approved by Ashwin Radhakrishnan.

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FFT with Windowing

This Module performs N-point FFT on PCM samples with Windowing. The FFT Output is given in the form of PCMx samples, the Blocksize of which is 3 * Schematic BlockSize.The first Schematic Block Size number of samples in a PCMx output contains the header information to be carried on to the next Module (say in this case IFFT). The header information contains fields such as PCMx type (to indicate Windowing), N.Since memory size depends on the value of N, downloading the Schematic (Link-Compile-Download) is necessary when N value is changed.

Input Pins

NameFormat [int/dec] - [control/audio]Function Description
Pin 0: Input decimal - Audio Real Audio Input
Pin 1: Input decimal - Audio Imaginary Audio Input

Output Pins

NameFormat [int/dec] - [control/audio]Function Description
Pin 0: Output(PCMx) decimal - Audio Real FFT Output
Pin 1: Output(PCMx) decimal - Audio Imaginary FFT Output

Grow Algorithm

The module does not support Growth and Add


GUI Control NameDefault ValueRangeFunction Description
FFT Size (N) 64 16 to 1024 Size of the FFT(Should be a power of 2,greater than or equal to 16)
Alpha 0.1 0.1 to 0.9 Alpha in the Raised Cosine window function

DSP Parameter Information

GUI Control NameCompiler NameFunction Description
FFT Size Ext_FFTProc_Algo_SC5xxAlg1N FFT Size
InvWS Ext_FFTProc_Algo_SC5xxAlg1InvWS Used for Calculating window coefficients
Inv1MinA Ext_FFTProc_Algo_SC5xxAlg1Inv1MinA Needed for IFFT to get back the orginal signal based on Alpha
Alpha Ext_FFTProc_Algo_SC5xxAlg1Alpha Alpha in the Raised Cosine window function


  • Green - Algorithm Name
  • Red - Instance Number (Changes for each instance)
  • Blue - Parameter Name

Algorithm Description

The input samples to the module are windowed first using a Raised cosine Window. IFFT is computed after the windowing for 2N samples where N corresponds to the Size set in the GUI. The twiddle coefficients are calculated within the code and output is given as PCMx samples.

Supported ICs

  1. ADSP215xx
  2. ADSPSC5xx
resources/tools-software/sigmastudio/toolbox/frequencydomain/fftwindow.txt · Last modified: 27 Jun 2019 07:22 by Ashwin Radhakrishnan