Digital Sound & Music: Concepts, Applications, & Science, Chapter 6, last updated 6/25/2013
result of ring modulation
Figure 6.53 Ring modulation using two sinusoidals
Phase Modulation (PM)
Even more interesting audio effects can be created with phase (PM) and frequency modulation
(FM). We're all familiar with FM radio, which is based on sending a signal by frequency
modulation. Phase modulation is not used extensively in radio transmissions because it can be
ambiguous to interpret at the receiving end, but it turns out to be fairly easy to implement PM in
digital synthesizers. Some hardware-based synthesizers that are commonly referred to as FM
actually use PM synthesis internally the Yamaha DX series, for example.
Recall that the general equation for a cosine waveform is where f is the
frequency and is the phase. Phase modulation involves changing the phase over time.
Equation 6.3 uses phase modulation to generate a digital signal.
( )
Equation 6.3 Phase modulation for digital synthesis
Phase modulation is demonstrated in MATLAB with the following statements:
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