Overview

2nd order IIR filter

Discussion

Standard second order 5 multiply recursive filter. The module is designed to operate on multiple channels and applies the same coefficients across all channels. The state array is allocated to contain 2*numChannels values. The frequency response of the module is determined by the values of the 5 coefficients, and the coefficients come directly from the MATLAB second order representation. The leading a0 coefficient is not supplied and is assumed to equal 1.0. The order of the coefficients must be [b0 b1 b2 a1 a2]. The module implements the difference equation: $y[n]=b_0x[n]+b_1x[n-1]+b_2x[n-2]-a_1y[n-1]-a_2y[n-2].$

Type Definition

typedef struct _ModuleBiquad
{
    ModuleInstanceDescriptor instance;            // Common Audio Weaver module instance structure
    FLOAT32 b0;                                   // First numerator coefficient.
    FLOAT32 b1;                                   // Second numerator coefficient.
    FLOAT32 b2;                                   // Third numerator coefficient.
    FLOAT32 a1;                                   // Second denominator coefficient.
    FLOAT32 a2;                                   // Third denominator coefficient.
    FLOAT32* state;                               // State variables. 2 per channel.
} ModuleBiquadClass;

Variables

Properties

Name	Type	Usage	isHidden	Default value	Range	Units
hardware_specific_struct_pointer	void *	state	1		Unrestricted	hardware_specific_struct_pointer

Pins

Input Pins

Name: in

Description: Complex input

Data type: float

Channel range: Unrestricted

Block size range: 3, 5, 9, 17, 33, 65, 129, 257, 513, 1025, 2049, 4097, 8193

Sample rate range: Unrestricted

Complex support: Complex

Output Pins

Name: out

Description: Real input

Data type: float

Scratch Pins

Channel count: 1

Block size: 4

Sample rate: 48000

MATLAB Usage

File Name: ifft_module.m

 M=ifft_module(NAME)
 Computes the inverse FFT of a real time domain sequence.  The input
 block is complex valued with a blockSize of N/2+1.  The output is
 real data of length N.  The module supports multichannel signals.
 Arguments:
    NAME - name of the module.

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(8.D.2.3) Biquad