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!

Basic Generator Operation - Your First Output Sound

When Daqarta first starts up, the program name, version, and Web address will appear in the center of the screen, in the "trace" area normally used to display waveforms and spectra. The Generator dialog is visible on the right side. At other times, this dialog may be invoked via the small unlabeled button below the Generator button in the toolbar above the trace area, or by the CTRL+G accelerator key, or by selecting from the Edit menu (ALT+E, G).

Sound output begins when the Generator On/Off button at the top of the dialog is toggled on. This acts like a "master switch" for the whole signal generator. You can toggle this at any time, even if this dialog is not visible, via the Generator button in the toolbar or via the ALT+G accelerator key.

Note that the first time you toggle the Generator on after installing Daqarta, the volume slider dialog will open and a message box will warn of possible loud volume, but there will be no sound output until you click 'OK'. You should set the Master and/or Wave volumes very low before you hit 'OK', then raise them gradually to the level you want.

You might think that it would be safe to just keep the current volume settings, on the assumption that if they were appropriate for prior listening before starting Daqarta, they would still be fine for Generator test signals. But normal music has a very low average level, compared to its peak level... and the default sine wave is always at peak level. So if you have set the volume such that a low average level is comfortable for music, the high average level of the sine may be quite a bit louder.

(Don't worry, Daqarta saves all sound card settings before it starts, and restores them on exit. Any changes you make while in Daqarta, stay in Daqarta and will be used only in future Daqarta sessions.)

Once the Generator is on, you should see a waveform display of the output signal in the trace area. The default sound is a continuous 440 Hz sine wave on the Left channel of the Generator, but sound cards typically send mono signals to both Left and Right outputs via the mixer controls.

Of course, all this presumes that your speakers or headphones are properly connected and functioning! See the No Sound Output topic in the Troubleshooting section if you still don't have sound.

If you do hear sound but it is distorted or stuttering instead of a pure, steady tone, see Distorted Sound Output or Stuttering Sound Output in the Troubleshooting section.

Once you have good sound output, you are ready to learn the Generator control fundamentals.

To get started, click on the Left Wave Controls button. That will open the Left Stream 0 dialog, which has a Wave button that will allow you to change the waveform from the default Sine. There is also a Tone Freq control that shows the default 440 Hz frequency. Try changing the waveform and frequency, while listening to the results and observing the waveforms on the trace.

So far you should be hearing the same tone in both channels, due to the way most sound cards operate when given a mono signal. To try stereo, go back to the main Generator dialog and toggle the Right button on at the top. The sound from the right channel should stop, because none of its Stream dialogs have been toggled on yet. Click the Right Wave Controls button, then click the Stream On button near the top of the Right Stream 0 dialog you've just opened.

Right Stream 0 is set to produce the same 440 Hz sine as Left, so (if you didn't change the Left Stream 0 from its defaults) you'll hear the same sound from both channels. Try setting the Tone Freq control to 441 Hz. You will hear a 1 Hz beat frequency; if you listen through headphones you'll hear Binaural Beats. See the Monaural and Binaural Beats mini-app discussion for more details and additional things to try.

Remember, you can always right-click any control at any time to see its Help topic, so feel free to experiment with the other controls, such as those in the Modulation section.

At the top of the Stream dialog are buttons marked Left or Right to denote the channel, plus Stream select buttons numbered 0 through 3. There are actually 4 completely independent streams for each stereo channel. By default these are summed together, such as to add specific harmonic content to a fundamental wave. (Make sure that the sum of all the stream Level settings doesn't exceed 100%, however.) Alternatively, one or more streams can act as modulation sources for other streams.

If you have a multi-channel sound card, you can use any or all of these 8 streams to create up to 8 independent output signals, each of which can be any combination of the 8 streams. These are controlled from the Multi-Channel Outputs dialog button on the main Generator dialog.

If you want to preserve your changes to the Generator setup, close the Stream dialog to return to the main Generator dialog, and click Save Setup. (Otherwise, you'll be prompted to save any changes when you exit Daqarta.)

The default file name is "Setup", which is actually Setup.GEN since all setups have a GEN file extension. If you save to that name, your new setup will be loaded as the default sound in future sessions. Otherwise, pick an appropriate name, and whenever you want to load that sound again you can select it via the Load Setup button.


See also Daqarta Screen Tour, Basic Input Operation - Your First Input Signal




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