Question
What is the name of the process that changes the phase angle of an RF signal to convey information?
Answer Options
- A) Phase convolution
- B) Phase modulation
- C) Phase transformation
- D) Phase inversion
Correct Answer: B
Explanation
Modulation is the process of altering a characteristic of a carrier wave to encode information. If the characteristic being altered is the carrier’s phase, the process is called phase modulation.
In phase modulation, the instantaneous phase angle of the Radio Frequency (RF) carrier is varied in direct proportion to the amplitude of the modulating signal (e.g., voice or data). This is closely related to frequency modulation (FM), and for amateur purposes, Phase Modulation (PM) and FM are often treated as equivalent emissions since a change in phase is mathematically related to a change in frequency.
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