JPL's Wireless Communication Reference Website Chapter: Analog and Digital Transmission Section: Analog Modulation

Amplitude modulation

Figure: Phasor Diagram for AM with tonal modulation.

In the animation below, we demonstrate the phasor motion for AM with tonal modulation. The three blue phasor represent

• the carrier, i.e., a stationary inphase component.
• the lower sideband, rotating clockwise
• the upper sideband, rotating counterclockwise

Note that the quadrature phase component of the resulting signal (in black) is always zero, and that the inphase component is always non-negative.

Java^TM Applet: Phasor diagram of a carrier with AM tone modulation.

JPL's Wireless Communication Reference Website © 1993, 1996.