Why is de-emphasis used in FM communications receivers?
The correct answer is A: For compatibility with transmitters using phase modulation. Why is de-emphasis used in FM communications receivers is for compatibility with transmitters using phase modulation. De-emphasis compensates for pre-emphasis used with phase modulation. For amateur radio operators, this is important for FM systems. Understanding this helps when working with FM receivers.
Exam Tip
De-emphasis in FM receivers = for compatibility with transmitters using phase modulation. Think 'D'e-'E'mphasis = 'D'emodulates 'E'mphasized signal (compatibility). De-emphasis compensates for pre-emphasis used with phase modulation. Not noise reduction, not higher efficiency, not distortion removal - just compatibility with phase modulation.
Memory Aid
"De-emphasis in FM receivers = for compatibility with transmitters using phase modulation. Think 'D'e-'E'mphasis = 'C'ompatibility. De-emphasis compensates for pre-emphasis used with phase modulation. Important for FM systems."
Real-World Application
De-emphasis used in FM communications receivers: It's for compatibility with transmitters using phase modulation. Phase-modulated transmitters use pre-emphasis, so receivers use de-emphasis to restore the original frequency response. This is the reason - compatibility with phase modulation.
Key Concepts
Why Other Options Are Wrong
Option B: Incorrect. Reducing impulse noise reception isn't the reason - de-emphasis is for compatibility with phase modulation. Noise reduction isn't the reason.
Option C: Incorrect. For higher efficiency isn't the reason - de-emphasis is for compatibility with phase modulation. Higher efficiency isn't the reason.
Option D: Incorrect. Removing third-order distortion products isn't the reason - de-emphasis is for compatibility with phase modulation. Distortion removal isn't the reason.
题目解析
The correct answer is A: For compatibility with transmitters using phase modulation. Why is de-emphasis used in FM communications receivers is for compatibility with transmitters using phase modulation. De-emphasis compensates for pre-emphasis used with phase modulation. For amateur radio operators, this is important for FM systems. Understanding this helps when working with FM receivers.
考试技巧
De-emphasis in FM receivers = for compatibility with transmitters using phase modulation. Think 'D'e-'E'mphasis = 'D'emodulates 'E'mphasized signal (compatibility). De-emphasis compensates for pre-emphasis used with phase modulation. Not noise reduction, not higher efficiency, not distortion removal - just compatibility with phase modulation.
记忆口诀
De-emphasis in FM receivers = for compatibility with transmitters using phase modulation. Think 'D'e-'E'mphasis = 'C'ompatibility. De-emphasis compensates for pre-emphasis used with phase modulation. Important for FM systems.
实际应用示例
De-emphasis used in FM communications receivers: It's for compatibility with transmitters using phase modulation. Phase-modulated transmitters use pre-emphasis, so receivers use de-emphasis to restore the original frequency response. This is the reason - compatibility with phase modulation.
错误选项分析
Option B: Incorrect. Reducing impulse noise reception isn't the reason - de-emphasis is for compatibility with phase modulation. Noise reduction isn't the reason. Option C: Incorrect. For higher efficiency isn't the reason - de-emphasis is for compatibility with phase modulation. Higher efficiency isn't the reason. Option D: Incorrect. Removing third-order distortion products isn't the reason - de-emphasis is for compatibility with phase modulation. Distortion removal isn't the reason.
知识点
De-emphasis, Used in FM communications receivers, Compatibility, Transmitters using phase modulation
Verified Content
Question from official FCC Extra Class question pool. Explanation reviewed by licensed amateur radio operators.