Measurement

Discussion

THIS MODULE IS DEPRECATED AND NOT RECOMMENDED FOR NEW DESIGNS. PLEASE USE THE MeasurementV2 MODULE INSTEAD.

This module will periodically output the stimulus signal. On the measurement side, the received signal of length L will be measured and averaged. The number of times that the stimulus signal is output and the received signal measured is numReps. The average of the recorded signal is in the response buffer. The trigger is a parameter which the PC sets to trigger the measurement. This will initially be 0 (waiting), then set to 1 by PC (start measurement). Once the measurement is completed, it will be set to 0.

Follow these steps to plot the measurement. (Note: This requires AudioWeaver Pro Edition)

1) Run the layout in Designer.

2) While running, check the trigger box on the measurement inspector.

3) Get the running layouts structure in Matlab:

>> GSYS = get_gsys();

4) Next read out the stimulus and response in Matlab command window:

>> x = GSYS.SYS.Measurement1.response;

>> z = GSYS.SYS.Measurement1.stimulus;

5) Next compute the transfer function and plot it. For example, if you have the signal processing toolbox you can do:

>>[tf, f] = tfestimate(z,x,[],[],[],48000);

>> plot(f,abs(tf));shg

Module Pack

Advanced

ClassID

classID = 1296

Type Definition

typedef struct _ModuleMeasurement
{
ModuleInstanceDescriptor instance;            // Common Audio Weaver module instance structure
INT32 L;                                      // Length of the stimulus signal.
INT32 numReps;                                // Number of times to repeat the stimulus and average the result
INT32 trigger;                                // state variable/parameter which the PC sets to trigger the measurement.
INT32 readIndex;                              // Index used for circular reading
INT32 stateIndex;                             // Index used for state
INT32 cnt;                                    // Index used to measure the response
FLOAT32* stimulus;                            // Column vector of length L holding the stimulus signal
FLOAT32* response;                            // Holds the time average measured signal
} ModuleMeasurementClass;

Variables

Properties

Name	Type	Usage	isHidden	Default Value	Range
L	int	const	0	2048	Unrestricted
numReps	int	parameter	0	16	1:1024
trigger	int	parameter	0	0	0:1
readIndex	int	state	1	0	Unrestricted
stateIndex	int	state	1	0	Unrestricted
cnt	int	state	1	0	Unrestricted
stimulus	float*	parameter	0	[2048 x 1]	Unrestricted
response	float*	derived	0	[1 x 2048]	Unrestricted

Pins

Input Pins


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

Output Pins


Name	out
Description	audio output
Data Type	float

Matlab Usage

File Name: measurement_module.m 
 M=measurement_module(NAME, L) 
 Audio Weaver module which performs transfer function measurements  
 using a stimulus and response.  The module outputs the stimulus signal 
 and averages the response over multiple repetitions.  Arguments: 
    NAME - name of the module 
    L - length of the measurement signal, in samples