SbComplexFIR

Overview

Sub-band Complex FIR Filter module

Discussion

Part of DSP Concepts IP for implementing long FIR filters in the frequency domain. This module implements a complex FIR filter within each subband of a filterbank. At instantiation time, you specify the number of taps in each complex filter The complex coefficients array (coeffs) will be sized as FFTSize * numTaps, so each bin has its own set of coefficients of length numTaps. The coeffs array requires all the real coefficients in the first half of the array, followed by the imaginary coefficients. The ordering of the coeff array is:

[realTap0Bin0, realTap0Bin1... realTap0BinM, realTap1Bin0, realTap1Bin1... realTapNBinM, imagTap0Bin0... imagTap0BinM, imagTap1Bin0... imagTapNBinM]

The module allocates memory for the complex FIR coefficients and state variables and at run-time implements the complex convolutions

Module Pack

Advanced

ClassID

classID = 1322

Type Definition

typedef struct _ModuleSbComplexFIR
{
ModuleInstanceDescriptor instance;            // Common Audio Weaver module instance structure
INT32 numTaps;                                // Length of each complex FIR filter
INT32 stateIndex;                             // Write index in to current complex state variables
FLOAT32* state;                               // FIR filter state memory
FLOAT32* coeffs;                              // FIR filter coeffs array
} ModuleSbComplexFIRClass;

Variables

Properties

Name	Type	Usage	isHidden	Default Value	Range
numTaps	int	const	1	8	Unrestricted
stateIndex	int	state	1	0	Unrestricted
state	float*	state	1	[512 x 1]	Unrestricted
coeffs	float*	parameter	0	[512 x 1]	Unrestricted

Pins

Input Pins


Name	in
Description	complex input
Data type	float
Channel range	1
Block size range	Unrestricted
Sample rate range	Unrestricted
Complex support	Complex

Output Pins


Name	out
Description	complex output
Data Type	float

Matlab Usage

File Name: sb_complex_fir_module.m 
 M = sb_complex_fir_module(NAME, NUMTAPS, FFTSIZE) 
 Creates a module which perform complex FIR filtering.  The module operates on  
 complex subband data.  Arguments: 
    NAME - name of the module. 
    NUMTAPS - Number of taps in each complex FIR filter. 
    FFTSIZE - optional argument which sets the default size of the IO pins. 
              By default, FFTSIZE = 256 and it will be overwritten in pre-build 
              function. 

 This module is part of DSPC IP for efficient fast convolution.