Overview

Sweep generator

Discussion

Creates a sweep signal generator for use in the Audio Weaver environment. This module has a single channel output pin and generates sweep sine signals with definable start and stop frequencies and sweep times. Sweep generators are commonly used to test the frequency response of electronic filter circuits or speakers.

Trigger parameter allows controlling start and stop of the sweep. This will initially be 0 (waiting), set to 1 to start the sweep. After sweep is completed and the time of the padding samples elapsed the trigger is set to 0 by the module.

If the trigger is used as input pin, it overrides the trigger parameter functionality and directly controls start (1) and stop (0) of the sweep.

Type Definition

typedef struct _ModuleSweepGen
{
    ModuleInstanceDescriptor instance;            // Common Audio Weaver module instance structure
    INT32 trigger;                                // State variable/parameter to trigger sweep on/off.
    INT32 sweepType;                              // Specifies a Linear or a Logarithmic sweep.
    FLOAT32 startFreq;                            // Frequency at which the sweep starts.
    FLOAT32 stopFreq;                             // Frequency at which the sweep ends.
    INT32 sweepTime;                              // The time interval in samples of the sweep between the start frequency and the stop frequency
    FLOAT32 amplitude;                            // Amplitude in linear units.
    INT32 padding;                                // Number of zero samples before repeating the sweep cycle.
    INT32 duration;                               // Sweep time in samples.
    FLOAT32 startIncr;                            // Increment start value.
    FLOAT32 endIncr;                              // Increment target vallue.
    FLOAT32 dIncr;                                // Delta increment.
    FLOAT32 momentaryIncr;                        // Momentary increment.
    FLOAT32 phase;                                // The stored phase of the sweep function.
    INT32 sampleCnt;                              // Momentary sample counter.
    INT32 paddingCnt;                             // Momentary padding counter.
    UINT32 pinID;                                 // Specifies which control pins are available.
} ModuleSweepGenClass;

Variables

Properties

Name	Type	Usage	isHidden	Default value	Range	Units
trigger	int	state	0	0	0:1
sweepType	int	parameter	0	0	0:1
startFreq	float	parameter	0	20	1:24000	Hz
stopFreq	float	parameter	0	24000	1:24000	Hz
sweepTime	int	parameter	0	48000	1:2880000	samples
amplitude	float	parameter	0	1	0:1	linear
padding	int	parameter	0	0	0:32767	samples
duration	int	derived	1	48000	Unrestricted
startIncr	float	derived	1	0.0004167	Unrestricted
endIncr	float	derived	1	0.5	Unrestricted
dIncr	float	derived	1	1.041e-05	Unrestricted
momentaryIncr	float	state	1	0.0004167	Unrestricted
phase	float	state	1	0	Unrestricted
sampleCnt	int	state	1	0	Unrestricted
paddingCnt	int	state	1	0	Unrestricted
pinID	uint	const	1	1	Unrestricted

Pins

Input Pins

Name: trigger

Description: Flag to trigger sweep on/off

Data type: int

Channel range: 1

Block size range: 1

Sample rate range: Unrestricted

Complex support: Real

Output Pins

Name: out

Description: audio output

Data type: float

MATLAB Usage

File Name: sweep_gen_module.m

 M=sweep_gen_module(NAME, SAMPLERATE, BLOCKSIZE, TRIGGERPIN)
 Creates a sweep signal generator for use in the Audio Weaver 
 environment. This module has a single channel output pin and generates 
 sweep sine signals with definable start and stop frequencies and duration
 times.
  
 Arguments:
    NAME               - name of the module.
    BLOCKSIZE          - number of samples per output channel.  
                         By default, BLOCKSIZE = 256.
    SAMPLERATE         - sample rate of the output signal, in Hz.  
                         By default, SAMPLERATE = 48000.
    TRIGGERPIN         - boolean that determines whether the module exposes an 
                         input pin that allows en/disabling during run-time