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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.
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Composer.GEN Setup File

This setup demonstrates one way to use the Expnote.DAT file. It "composes" music that has a vaguely Oriental flavor, using the Pentatonic scale equivalent to the black keys on a piano keyboard. This is also the scale that is used in certain traditional folk styles of the British Isles, American Mountaineers, and Native Americans. You may thus be able to modify the setup to sound more like one of those, or you may experiment with other tunings.

Composer.GEN uses a White Noise source ( Stream 1) to supply random values that are then used to select random notes from the proper range of Expnote.DAT (Stream 2), which are in turn used to modulate the frequency of a Ramp Wave (Stream 3) to get the actual notes. Burst is used on the ramp, set to give a different duration than the interval between random note changes, to make things more interesting. To add still more dynamics, the ramp slope is modulated by a slow random souce (Stream 0).

Additional modulation could be used, such as by adding AM to the Stream 3 output at a 3-7 Hz "tremolo" rate, or adding a similar AM to the random note frequencies of Stream 2 to provide "vibrato". All of this uses only the Left channel; the Right is still free for a second instrument "voice".

The basic setup plays a very long "song"... it doesn't repeat for over 100 billion years! Here is a quick summary:

All Stream Level settings are 100%. The Burst durations and Timing Factor assume a sample rate of 44100 Hertz. You may wish to try various modifications. In particular, try toggling Stream 3 Burst off, or set different durations. Try different Stream 3 waves instead of Ramp, with different modulation (since only Ramp allows Slope modulation).


Applications:

Frequency response

Distortion measurement

Speech and music

Microphone calibration

Loudspeaker test

Musical instrument tuning

Animal sound

Evoked potentials

Rotating machinery

Vehicle pass-by noise

Product test

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