BiquadCascadeHPFract32

Overview

2nd order cascaded IIR filter, high precision

Discussion

Second order cascaded 5 multiply recursive filter with algorithm precision uses 24x24 with 56-bit accumulator. The module is designed to operate on multiple channels and applies the same coefficients across all channels. The state array is allocated to contain 6*numStages*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 module implements the difference equation:

\(y[n]=b_0x[n]+b_1x[n-1]+b_2x[n-2]-a_1y[n-1]-a_2y[n-2].\)

Module Pack

Advanced

ClassID

classID = 1412

Type Definition

typedef struct _ModuleBiquadCascadeHPFract32
{
ModuleInstanceDescriptor instance;            // Common Audio Weaver module instance structure
INT32 numStages;                              // Number of cascaded stages of the second order filter.
INT32 bShift;                                 // Number of bits to shift of Numerator coefficients
INT32 aShift;                                 // Number of bits to shift of Denominator coefficients
FLOAT32* coeffs;                              // coefficients
fract32* coeffsFract32;                       // coefficients in Fract32
fract32* state;                               // State variables.  6 per channel.
void * updateStateActive;                     // Used as internal state variable without breaking compatibility
void * hardware_specific_struct_pointer;      // Usually NULL, but target specific optimizations can make use of it
} ModuleBiquadCascadeHPFract32Class;

Variables

Properties

Name	Type	Usage	isHidden	Default Value	Range
numStages	int	const	0	1	1:1:32
bShift	int	parameter	1	1	Unrestricted
aShift	int	parameter	1	1	Unrestricted
coeffs	float*	parameter	0	[5 x 1]	Unrestricted
coeffsFract32	fract32*	derived	0	[5 x 1]	Unrestricted
state	fract32*	state	1	[6 x 1]	Unrestricted
updateStateActive	void *	state	1		Unrestricted
hardware_specific_struct_pointer	void *	state	1		Unrestricted

Pins

Input Pins


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

Output Pins


Name	out
Description	audio output
Data Type	fract32

Matlab Usage

File Name: biquad_cascadeHP_fract32_module.m 
 M=biquad_cascadeHP_fract32_module(NAME, NUMSTAGES) 
 Creates a second order IIR cascaded filter Fract32 (biquad) for use with the Audio 
 Weaver.  Arguments: 
     NAME - name of the module. 
    NUMSTAGES - number of second order filter stages.