What is the name of the process that changes the phase angle of an RF signal to convey information?
The correct answer is B: Phase modulation. The name of the process that changes the phase angle of an RF signal to convey information is phase modulation. Phase modulation varies the phase of the carrier based on the modulating signal. For amateur radio operators, this is a fundamental modulation type. Understanding this helps when operating different modes.
Exam Tip
Change phase angle to convey information = phase modulation. Think 'P'hase 'M'odulation = 'P'hase 'M'odified to convey information. Phase modulation varies the phase of carrier based on modulating signal. Not convolution, not transformation, not inversion - just phase modulation.
Memory Aid
"Change phase angle to convey information = phase modulation. Think 'P'hase 'M'odulation = 'P'hase 'M'odified. Phase modulation varies the phase of carrier based on modulating signal. Standard modulation type."
Real-World Application
Phase modulation: The phase angle of the RF carrier is varied based on the audio signal. As the audio changes, the carrier phase shifts. This is phase modulation - the phase angle is changed to convey information. Phase modulation is used in some digital modes and is related to frequency modulation.
Key Concepts
Why Other Options Are Wrong
Option A (Phase convolution): Incorrect. Phase convolution isn't a standard modulation term - phase modulation is the correct term. Convolution is a mathematical operation, not modulation.
Option C (Phase transformation): Incorrect. Phase transformation isn't a standard modulation term - phase modulation is the correct term. Transformation is too general.
Option D (Phase inversion): Incorrect. Phase inversion is flipping phase 180°, not modulation - phase modulation varies phase continuously. Inversion is different.
题目解析
The correct answer is B: Phase modulation. The name of the process that changes the phase angle of an RF signal to convey information is phase modulation. Phase modulation varies the phase of the carrier based on the modulating signal. For amateur radio operators, this is a fundamental modulation type. Understanding this helps when operating different modes.
考试技巧
Change phase angle to convey information = phase modulation. Think 'P'hase 'M'odulation = 'P'hase 'M'odified to convey information. Phase modulation varies the phase of carrier based on modulating signal. Not convolution, not transformation, not inversion - just phase modulation.
记忆口诀
Change phase angle to convey information = phase modulation. Think 'P'hase 'M'odulation = 'P'hase 'M'odified. Phase modulation varies the phase of carrier based on modulating signal. Standard modulation type.
实际应用示例
Phase modulation: The phase angle of the RF carrier is varied based on the audio signal. As the audio changes, the carrier phase shifts. This is phase modulation - the phase angle is changed to convey information. Phase modulation is used in some digital modes and is related to frequency modulation.
错误选项分析
Option A (Phase convolution): Incorrect. Phase convolution isn't a standard modulation term - phase modulation is the correct term. Convolution is a mathematical operation, not modulation. Option C (Phase transformation): Incorrect. Phase transformation isn't a standard modulation term - phase modulation is the correct term. Transformation is too general. Option D (Phase inversion): Incorrect. Phase inversion is flipping phase 180°, not modulation - phase modulation varies phase continuously. Inversion is different.
知识点
Phase modulation, Phase angle, RF signal, Modulation types
Verified Content
Question from official FCC General Class question pool. Explanation reviewed by licensed amateur radio operators.