Overview
LMS Norm fract32 filter
Discussion
The LMS fract32 module implements a single channel, N-order FIR adaptive filter using a Normalized Least Means Squares algorithm. The module takes 2 single channel inputs: desired filter output and filter input (the reference signal). For every data sample the filter output is compared to the desired output and this information is used to update the filter taps according to the normalized LMS algorithm. The module always has 2 single channel ouputs: adaptive filter output and error signal, (desired filter output - actual filter output. The adaptation constant mu is visible as a user variable.
Type Definition
| Code Block |
|---|
typedef struct _ModuleLMSNormFract32
{
ModuleInstanceDescriptor instance; // Common Audio Weaver module instance structure
INT32 numTaps; // Length of the filter
FLOAT32 mu; // mu Step size
INT32 stateIndex; // Index of the oldest state variable in the array of state variables
INT32 prev_stateptr; // Index of the oldest state variable in the array of state variables
INT32 postShift; // Coefficient Scaling
fract32 mufract32; // mu Step size
fract32 E; // saves previous frame energy
fract32 x0; // saves previous input sample
fract32* coeffsfract32; // Coefficient array
fract32* state; // State variable array
} ModuleLMSNormFract32Class; |
Variables
Properties
Name | Type | Usage | isHidden | Default value | Range | Units |
numTaps | int | const | 0 | 31 | 1:1:5000 | samples |
mu | float | parameter | 0 | 0.02 | 0:0.999 | linear |
stateIndex | int | state | 1 | 0 | Unrestricted | |
prev_stateptr | int | state | 1 | 0 | Unrestricted | |
postShift | int | derived | 1 | 0 | Unrestricted | |
mufract32 | fract32 | derived | 1 | 0.02 | Unrestricted | |
E | fract32 | state | 1 | 0 | Unrestricted | |
x0 | fract32 | state | 1 | 0 | Unrestricted | |
coeffsfract32 | fract32* | derived | 0 | [31 x 1] | Unrestricted | |
state | fract32* | state | 1 | [62 x 1] | Unrestricted |
Pins
Input Pins
Name: in1
Description: audio input
...
Sample rate range: Unrestricted
Complex support: Real
Output Pins
Name: out1
Description: audio output
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Description: error output
Data type: fract32
MATLAB Usage
File Name: lms_norm_fract32_module.m
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