(8.D.2.7) Hysteresis
- Sam Stuart
Overview
Threshold with hysteresis
Discussion
The hysteresis module implements switching above and below a threshold. The module accepts floating-point inputs and outputs 0 when the signal level is below the threshold and 1 when above. Instead of just a single threshold the module incorporates hysteresis by having separate upper and lower thresholds. The output switches from 0->1 when the input signal rises above the upperThreshold and then stays at 1 until the signal drops below the lowerThreshold. The module is thus above to avoid frequent switching when signal levels are close to the threshold.
If you need just a straightforward comparison against a threshold without hysteresis, use the logic_compare_const_modulue.m.
The module accepts multichannel signals and outputs a separate Boolean value per channel. The module operates on a sample-by-sample basis and the block size of the output equals the block size of the input.
When bypassed, the module continues to process data normally. That is, the module's processing function is called even when it is bypassed.
Type Definition
typedef struct _ModuleHysteresis
{
ModuleInstanceDescriptor instance; // Common Audio Weaver module instance structure
FLOAT32 upperThreshold; // Upper switching threshold
FLOAT32 lowerThreshold; // Lower switching threshold
INT32* state; // Current state per chanel
} ModuleHysteresisClass;Variables
Properties
Name | Type | Usage | isHidden | Default value | Range | Units |
upperThreshold | float | parameter | 0 | 1 | Unrestricted | Â |
lowerThreshold | float | parameter | 0 | -1 | Unrestricted | Â |
state | int* | state | 0 | [1 x 1] | Unrestricted | Â |
Pins
Input Pins
Name: in
Description: Input signal
Data type: float
Channel range: Unrestricted
Block size range: Unrestricted
Sample rate range: Unrestricted
Complex support: Real
Output Pins
Name: out
Description: Output signal
Data type: int
MATLAB Usage
File Name: hysteresis_module.m
M = hysteresis_module(NAME)
This module implements Boolean selection above and below a threshold
and adds hysteresis to the design to avoid frequent switching.
Arguments:
NAME - name of the module.Â