Daqarta
Data AcQuisition And Real-Time Analysis
Scope - Spectrum - Spectrogram - Signal Generator
Software for Windows
Science with your Sound Card!
The following is from the Daqarta Help system:

Features:

Oscilloscope

Spectrum Analyzer

8-Channel
Signal Generator

(Absolutely FREE!)

Spectrogram

Pitch Tracker

Pitch-to-MIDI

DaqMusiq Generator
(Free Music... Forever!)

Engine Simulator

LCR Meter

Remote Operation

DC Measurements

True RMS Voltmeter

Sound Level Meter

Frequency Counter
    Period
    Event
    Spectral Event

    Temperature
    Pressure
    MHz Frequencies

Data Logger

Waveform Averager

Histogram

Post-Stimulus Time
Histogram (PSTH)

THD Meter

IMD Meter

Precision Phase Meter

Pulse Meter

Macro System

Multi-Trace Arrays

Trigger Controls

Auto-Calibration

Spectral Peak Track

Spectrum Limit Testing

Direct-to-Disk Recording

Accessibility

Applications:

Frequency response

Distortion measurement

Speech and music

Microphone calibration

Loudspeaker test

Auditory phenomena

Musical instrument tuning

Animal sound

Evoked potentials

Rotating machinery

Automotive

Product test

Contact us about
your application!

Generator dB Slider Dialog


Macros: dB_L, dB_R, dB_Trk

After the mixer has been calibrated, you can select the Use dB option in the Attenuator Options dialog (wide button just below the volume controls on the main Signal Generator dialog). After you do that, the small 'Vol' button between the Left and Right volume controls is replaced with 'dB', which you can click to open the dB Slider dialog. The F9 function key will also open this dialog even when the Generator dialog is not open.

Unlike the Volume dialog, this has only one large pair of sliders with associated edit controls. There is also an additional Track option via 3 radio buttons between the sliders.

The dB slider is similar to the Volume Slider, which allows independent adjustment of Master and Wave volume controls. But the dB slider simultaneously adjusts both the Master and Wave volumes, as needed, to get an overall dB setting. The individual Master and Wave settings are not shown.

The slider operation is dependent upon other settings in the Attenuator Options dialog. If you set the dB Relative / User Units button to 'dB Relative', the edit controls (mirroring the main Generator Volume edit controls) will be in dB relative to maximum output. Values will thus run negative from 0 dB. If you set 'dB User Units' with User Units active, the maximum value will be whatever value you have specified in the User Units Calibration dialog for each Left and Right Output. The slider title and labels will show 'dB' or 'dB:Volt' (or whatever unit you used) accordingly.

With 'dB User Units', if you have loaded a speaker calibration file (.CAL or .FRD) for a channel, and its SPL button is active, then whenever User Units is active the dB slider will be calibrated in SPL units. Without the calibration file, you can force SPL units by setting the Units Name to "Pa" to enable the SPL button.

When you set Use Level, the Max control below it specifies the maximum amount of attenuation that Level will add. The default value is 96 dB. That amount will likewise extend the range of the slider controls.

The Atten Scroll Step only applies to scrolling the edit controls when Use Level is active; the sliders always use 1 dB steps.

One final consideration regarding Use Level operation: When this is active, a change in volume usually requires Daqarta to compute new waveform levels in order to hit the desired volume exactly. The Stream Level controls don't change visibly, but their effective values are adjusted and the output waveform is recomputed just as though Level had been changed directly.

Sound output is stopped momentarily and restarted from the beginning with the new waveform; it does not just continue where it left off. This causes a discontinuity in the waveform, which results in a click. A single click may not be a problem when entering a value into an edit control, but a whole stream of clicks can be very annoying while moving a slider over any appreciable distance. You can avoid these clicks by leaving Use Level off, and relying upon the native resolution of the mixer hardware.

The Track radio buttons allow two different modes besides Off (which gives normal independent Left and Right operation). Track Equal mode is similar to the single Track mode available in the uncalibrated Volume slider dialog: Any attenuation you set on either channel is set identically on the other.

Track Rel maintains the a constant dB difference between the channels, behaving like an ideal Balance control. To use this mode, first use Track Off to set the two channels independently, such that they have the desired difference between them. Then set Track Rel and that difference will be maintained as you change either attenuator.

There are a couple of points to consider when using Track Rel. Ideally, you should have Use Level active so that Daqarta can create any arbitrary volume in case the attenuators can't hit it exactly. This may entail the clicking behavior noted above.

Also, note that the total control range can't be exceeded. Suppose, for example, that you set Right to be 3 dB louder than Left. If you move Left to -3 dB, then Right will be forced to 0 dB. If you then move Left to -2 dB, Right can't go to +1 dB (in dB Relative mode), so it just remains at 0 dB. Now when you reduce the Left volume, there will only be a 2 dB difference between channels.

A similar situation happens in reverse at the low end of the range. Again, if Right is 3 dB louder than Left, you can't move it any lower than 3 dB from the bottom because Left can't be driven lower than the bottom. If you do, then the difference between the channels will necessarily be reduced.

Below the Track buttons are Auto and Mute buttons. These will be disabled if your sound card does not support the Mute function.

Auto is a convenient duplicate of Generator Auto-Mute in Edit Menu - Run Preferences.

Mute allows the Generator output to be muted without affecting the volume setting. It only works if the sound card supports mute controls (most do). Only the Wave volume is muted, not the Master volume

Mute is especially useful when you want to create signals only for internal use, without any sound output. It is typically used for Pitch-to-MIDI operation in DaqMusiq mode, where you want to use the Generator instead of the default (silent) random source.

Note that the Master volume is not affected by Mute, so in principle you can still control the MIDI synthesizer level with the dB slider, but this is not recommended. The dB values shown (intended for overall Generator levels) are irrelevant, but more importantly the control linearity is poor because it uses a mixture of Master and Wave steps, and with Mute active the Wave steps do nothing.

If Auto is active, then whenever the Generator is off the Mute button will be automatically disabled. The Generator output will be muted, even though the Mute button may not reflect that... it retains its prior state. You can toggle Auto off to re-enable Mute.


Macro Notes:

Note that the following macro commands assume that Use dB is active. If not, the macro will abort with an error message. To be safe, give a UseCal=dB command before using these.

dB_L=6 sets the Left Generator output to -6 dB. Note that 0 is loudest, and all entered values are assumed negative. (If you enter a sign, it is ignored.) Use dB_R to set the Right Generator output.

Unless Use Level is active, the resultant dB setting will be the closest value allowed by your sound card. (The actual value will be shown.) Different sound cards may have different dB step sizes, and the size is not constant over the whole attenuation range.

If Use Level is active, dB values will be exactly as entered.

Alternatively, db_L=>1 will make the Left Generator output one step louder (less negative) and dB_L=>-1 will make it one step softer (more negative). Unless Use Level is active, these steps will be the smallest steps allowed by your card at that point in its range.

If Use Level is active, the step size is determined by the Scroll Step setting.

dB_Trk=Off or dB_Trk=0 sets the Track mode to Off, so the Left and Right dB controls are independent. dB_Trk=Equ or dB_Trk=1 sets them to Equal, so changing one causes the other to change to match. dB_Trk=Rel or dB_Trk=2 sets Rel so the two channels maintain a constant relative difference. (Or nearly so, if Use Level is not active.)

GenMute=1 sets Auto (Generator Auto-Mute), GenMute=0 turns it off, and GenMute=x toggles the current state.

WaveMute=1 sets Mute, WaveMute=0 turns it off, and WaveMute=x toggles the current state. Note that Auto must be off for WaveMute to work, so you might want to first use GenMute=1.


See also Generator Volume/dB Slider Button, Attenuator Calibration, Signal Generator Control Dialog

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