Interactive Power Spectrum Demo, Version 2

Interactive signal generator with power spectrum display and sound output

Digital signal generator (simulator) with power spectrum display and sliders for "real time" control, useful for teaching and demonstrating the power spectra of different types of signals and the effect of signal duration and sampling rate. Version 1.1 adds sound output. The signal slider selects from 10 different signals (you can change these in RedrawSpectrum.m). The Time slider controls the total duration of signal, the Rate slider controls the sample rate, and the F1 and F2 sliders control the global variables f1 and f2 which are used in different ways in the different signals. The Sound slider has only two settings: OFF (down) and ON (up). When Sound is ON, each time a slider is moved, the signal (y) is sent to the Windows WAVE audio device. When Sound is OFF, no sound is played when a slider is moved. However, even when Sound is OFF, clicking on the Sound slider plays the signal once for each click.

The 10 pre-programmed signals are:

Sine wave of frequency f1 (Hz) and phase f2;

Sine wave burst of frequency f1 (Hz) and duration f2;

Square wave of frequency f1 (Hz) and phase f2;

Sawtooth wave of frequency f1(Hz);

440 Hz carrier amplitude modulated by sine wave of frequency f1 (Hz) and amplitude f2;

440 Hz carrier frequency modulated by sine wave of frequency f1 (Hz) and amplitude f2;

Sine wave of frequency f1 (Hz) modulated by Gaussian pulse of width f2;

Random white noise;

Sine wave of frequency f1 (Hz) and amplitude f2 plus random white noise;

Sine wave sweep from 0 to f1 (Hz).

See http://terpconnect.umd.edu/~toh/spectrum/HarmonicAnalysis.html

T. C. O'Haver ([e-mail]), version 1.1, May, 2007