PURPOSE: To compare and analyze the frequency spectra of various modulated sounds such as tremolo, vibrato, and beats.
DESCRIPTION: Using the Pasco Dual Function Generator, a 5000 Hz sine wave can be modulated by a 500 Hz sine wave and the spectrum of the modulated signal displayed using the spectrum analyzer. Amplitude modulation, frequency modulation, or double sideband modulation (sometimes called balanced modulation, or ring modulation with synthesizers) can be used. Two sine waves can be added together using the Dual Function Generator to produce beats, and the spectrum of the beats obtained and compared with that of double sideband modulation. The waveform is displayed on one trace and the spectrum on the other.
REFERENCES: (PIRA unavailable.)
EQUIPMENT: Dual function generator with loudspeaker, wave shape and spectrum scopes.
SETUP TIME: 15 min.
Go back to Lecture-Demonstration Home Page.