What is the name of the process that changes the instantaneous frequency of an RF wave to convey information?
The correct answer is D: Frequency modulation. The name of the process that changes the instantaneous frequency of an RF wave to convey information is frequency modulation. FM varies the frequency of the carrier based on the modulating signal. For amateur radio operators, this is a fundamental modulation type. Understanding this helps when operating FM.
Exam Tip
Change instantaneous frequency to convey information = frequency modulation. Think 'F'requency 'M'odulation = 'F'requency 'M'odified to convey information. FM varies the frequency of carrier based on modulating signal. Not convolution, not transformation, not conversion - just frequency modulation.
Memory Aid
"Change instantaneous frequency to convey information = frequency modulation. Think 'F'requency 'M'odulation = 'F'requency 'M'odified. FM varies the frequency of carrier based on modulating signal. Standard modulation type."
Real-World Application
Frequency modulation: The instantaneous frequency of the RF carrier is varied based on the audio signal. As the audio changes, the carrier frequency shifts. This is frequency modulation - the frequency is changed to convey information. FM is commonly used for voice communication on VHF/UHF.
Key Concepts
Why Other Options Are Wrong
Option A (Frequency convolution): Incorrect. Frequency convolution isn't a standard modulation term - frequency modulation is the correct term. Convolution is a mathematical operation, not modulation.
Option B (Frequency transformation): Incorrect. Frequency transformation isn't a standard modulation term - frequency modulation is the correct term. Transformation is too general.
Option C (Frequency conversion): Incorrect. Frequency conversion is changing frequency (mixing), not modulation - frequency modulation varies frequency based on signal. Conversion is different.
题目解析
The correct answer is D: Frequency modulation. The name of the process that changes the instantaneous frequency of an RF wave to convey information is frequency modulation. FM varies the frequency of the carrier based on the modulating signal. For amateur radio operators, this is a fundamental modulation type. Understanding this helps when operating FM.
考试技巧
Change instantaneous frequency to convey information = frequency modulation. Think 'F'requency 'M'odulation = 'F'requency 'M'odified to convey information. FM varies the frequency of carrier based on modulating signal. Not convolution, not transformation, not conversion - just frequency modulation.
记忆口诀
Change instantaneous frequency to convey information = frequency modulation. Think 'F'requency 'M'odulation = 'F'requency 'M'odified. FM varies the frequency of carrier based on modulating signal. Standard modulation type.
实际应用示例
Frequency modulation: The instantaneous frequency of the RF carrier is varied based on the audio signal. As the audio changes, the carrier frequency shifts. This is frequency modulation - the frequency is changed to convey information. FM is commonly used for voice communication on VHF/UHF.
错误选项分析
Option A (Frequency convolution): Incorrect. Frequency convolution isn't a standard modulation term - frequency modulation is the correct term. Convolution is a mathematical operation, not modulation. Option B (Frequency transformation): Incorrect. Frequency transformation isn't a standard modulation term - frequency modulation is the correct term. Transformation is too general. Option C (Frequency conversion): Incorrect. Frequency conversion is changing frequency (mixing), not modulation - frequency modulation varies frequency based on signal. Conversion is different.
知识点
Frequency modulation, Instantaneous frequency, RF wave, Modulation types
Verified Content
Question from official FCC General Class question pool. Explanation reviewed by licensed amateur radio operators.