WindowFract32

Overview

Applies a time domain window

Discussion

This module applies a time domain window to a signal. This operation is useful prior to taking the FFT of a signal and commonly occurs in STFT-based filterbanks. The module operates on multiple channels with all channels having the same window. The length of the window (WLEN) is specified at instantiation time. The module outputs a block of size [WLEN numChannels], where numChannels equals the number of channels in the input signal. This block is output everytime that the module's processing function is called.

The window coefficients are set to a Hamming window (raised cosine) at instantiation time. The window coefficients may subsequently be changed.

Module Pack

Advanced

ClassID

classID = 1356

Type Definition

typedef struct _ModuleWindowFract32
{
ModuleInstanceDescriptor instance;            // Common Audio Weaver module instance structure
INT32 winLen;                                 // Length of the window
INT32 postShift;                              // Number of bits to shift
FLOAT32* window;                              // Window coefficients
fract32* windowFract32;                       // Window coefficients in fractional representation
} ModuleWindowFract32Class;

Variables

Properties

Name	Type	Usage	isHidden	Default Value	Range	Units
winLen	int	const	0	256	1:1:8192	samples
postShift	int	derived	1	0	Unrestricted
window	float*	parameter	0	[256 x 1]	Unrestricted
windowFract32	fract32*	derived	1	[256 x 1]	Unrestricted

Pins

Input Pins


Name	in
Description	audio input
Data type	fract32
Channel range	Unrestricted
Block size range	256
Sample rate range	Unrestricted
Complex support	Real

Output Pins


Name	out
Description	audio output
Data Type	fract32

Matlab Usage

File Name: window_fract32_module.m 
 M=windowFract32_module(NAME, ILEN, WLEN) 
 Creates a module which applies a window. 
  Arguments: 
    NAME - name of the module. 
    ILEN - lenght of the input 
    WLEN - length of the window to apply. 

 This module is often used as part of a short term Fourier transform 
 filterbank.  The module operates on an arbitrary number of channels 
 with the same window and length parameters applied.