Overview
Cascade of second order Biquad filters
Discussion
A cascade of second order 5 multiply recursive filters. The module is designed to operate on multiple channels and applies the same coefficients across all channels. The state array is allocated to contain 4*numChannels*numStages values. Each 2nd order section implements the difference equation:
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The filter coefficients stored in the matrix .coeffs. This matrix is of dimension 5 x numStages and each column of the matrix corresponds to an individual 2nd order Biquad stage. Within each column, the coefficients are ordered as: $[b0; b1; b2; a1; a2].$
Type Definition
| Code Block |
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typedef struct _ModuleBiquadCascadeFract32
{
ModuleInstanceDescriptor instance; // Common Audio Weaver module instance structure
INT32 numStages; // Number of stages in the filter. The filter order = 2 * numStages
FLOAT32* coeffs; // Matrix of filter coefficients. The size of the matrix is 5 x numStages. Each column contains the variables for a biquad arranged as [b0; b1; b2; a1; a2].
fract32* coeffsFract32; // Matrix of filter coefficients. The size of the matrix is 5 x numStages. Each column contains the variables for a biquad arranged as [b0; b1; b2; a1; a2].
fract32* state; // State variables. 4 per channel.
INT32* postShift; // Number of bits to shift
} ModuleBiquadCascadeFract32Class; |
Variables
Properties
Name | Type | Usage | isHidden | Default value | Range | Units |
numStages | int | const | 0 | 1 | 1:1:32 | |
coeffs | float* | parameter | 0 | [5 x 1] | Unrestricted | |
coeffsFract32 | fract32* | derived | 1 | [5 x 1] | Unrestricted | |
state | fract32* | state | 1 | [4 x 1] | Unrestricted | |
postShift | int* | derived | 1 | [1 x 1] | Unrestricted |
Pins
Input Pins
Name: in
Description: audio input
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Sample rate range: Unrestricted
Complex support: Real
Output Pins
Name: out
Description: audio output
Data type: fract32
MATLAB Usage
File Name: biquad_cascade_fract32_module.m
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