PURPOSE: To demonstrate AM and FM signal modulation as an introduction to vibrato and tremolo.

DESCRIPTION: The Pasco Dual Function Generator is used to produce either amplitude modulation or frequency modulation using various combinations of sine, triangular, and square waves. Frequency modulation is pure vibrato and amplitude modulation is pure tremolo; actual vocal vibrato is a combination of pure vibrato and pure tremolo.

The three photographs above show (left to right) something close to amplitude modulation, frequency modulation, and double-sideband or ring modulation. The modulating signal is shown on the lower trace.

Click here to obtain setup charts for each of the types of modulation.

SUGGESTIONS:

REFERENCES: (PIRA unknown.)

EQUIPMENT: Dual function generator with loudspeaker and oscilloscope on scope/TV cart.

SETUP TIME: 5 min.