Deep Dive: E7E06
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.
Why Other Answers 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.
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 Example
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.
Source & Coverage
Question Pool: 2024-2028 Question Pool
Subelement: E7E
Reference: 2024-2028 Question Pool · E7 - Practical Circuits
Key Concepts
Verified Content
Question from the official FCC Extra Class pool. Explanation reviewed by licensed amateur radio operators and mapped to the E7E topic.