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

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	Units
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.