Amplitude Modulation in Waves

There are a number of ways to demonstration amplitude modulation, one of which is to use the setup for demonstrating beats. (E-002, see Related Items.)  E-002 is more suitable for demonstrating beats as frequencies can be adjusted.

The setup described here uses the Pasco Fourier Synthesizer, a multi-source waveform generator that produces the fundamental and harmonic frequencies of 440Hz..

1. Set the 8th and 9th harmonic sources to IN, set all other sources to OUT.
2. Connect the 10k output and trigger output of the Pasco fourier synthesizer to an oscilloscope.
3. Observe the amplitude modulation (beat frequencies)

Previously the demonstration uses a CRO display and the Pasco waveforms box, connected as shown in the historical diagram below.
Older Method:

1. Turn up brilliance control
2. Vary phase 0 - 90 degrees, 0 - 180 degrees or use phase control knob
3. Observe movement of beat frequency
4. Change shape of output waveform by changing either channel frequencies press reset button if out of phase