Ever since the early days of radio, modulation techniques have played an important part in electronic communications. A low-frequency voice or data signal is used to modulate some characteristic (usually the amplitude, phase, or frequency) of a carrier signal. This type of system represents an intentional use of modulation. In addition, unintentional modulation may be present, such as power line sidebands on an oscillator output or residual frequency modulation on an amplitude-modulated signal. Whether the modulation is intentional or not, a spectrum analyzer can be used to characterize and measure it.

Chapter Contents:

• 6.1 The Carrier
• 6.2 Amplitude Modulation
• 6.3 AM Measurements
• 6.4 Zero Span Operation
• 6.5 Other Forms of Amplitude Modulation
• 6.6 Angle Modulation
• 6.7 Narrowband Angle Modulation
• 6.8 Wideband Angle Modulation
• 6.9 FM Measurements
• 6.10 Combined AM and FM
• References

Inspec keywords: modulation

Other keywords: modulation technique; unintentional modulation; residual frequency modulation; oscillator output; amplitude modulated signal; power line sideband; spectrum analyzer; modulation measurement; electronic communication; carrier signal; data signal

Subjects: Modulation and coding methods