Next: Designer spectra Up: Modulation Previous: Phase modulation and FM Contents Index

# Exercises

1. A sound has fundamental 440. How could it be ring modulated to give a tone at 110 Hertz with only odd partials? How could you then fill in the even ones if you wanted to?

2. A sinusoid with frequency 400 and unit peak amplitude is squared. What are the amplitudes and frequencies of the new signal's components?

3. What carrier and modulation frequencies would you give a two-operator FM instrument to give frequencies of 618, 1000, and 2618 Hertz? (This is a prominent feature of Chowning's Stria [DJ85].)

4. Two sinusoids with frequency 300 and 400 Hertz and peak amplitude one (so RMS amplitude 0.707) are multiplied. What is the RMS amplitude of the product?

5. Suppose you wanted to make FM yet more complicated by modulating the modulating oscillator, as in:

   How, qualitatively speaking, would the spectrum differ from that of the simple two-modulator example (Section 5.5)?

6. A sinusoid at a frequency is ring modulated by another sinusoid at exactly the same frequency. At what phase differences will the DC component of the result disappear?

Next: Designer spectra Up: Modulation Previous: Phase modulation and FM Contents Index