How does a noise blanker work?
The correct answer is C: By reducing receiver gain during a noise pulse. How a noise blanker works is by reducing receiver gain during a noise pulse. When a noise pulse is detected, the receiver gain is momentarily reduced, blanking (removing) the noise. For amateur radio operators, this helps reduce impulse noise interference. Understanding this helps when using noise blankers.
Exam Tip
Noise blanker = reduces receiver gain during noise pulse. Think 'N'oise 'B'lanker = 'N'ulls 'B'riefly (reduces gain). When noise pulse detected, receiver gain is momentarily reduced to blank the noise. Not bandwidth increase, not redirection, not clipping - just gain reduction.
Memory Aid
"Noise blanker = reduces receiver gain during noise pulse. Think 'N'oise 'B'lanker = 'N'ulls 'B'riefly. When noise pulse detected, receiver gain is momentarily reduced to blank the noise. Effective against impulse noise."
Real-World Application
Impulse noise (like ignition noise) is interfering with your reception. You activate the noise blanker. When a noise pulse is detected, the receiver gain is momentarily reduced, blanking the noise. This allows you to copy signals between noise pulses. Noise blankers are very effective against impulse noise.
Key Concepts
Why Other Options Are Wrong
Option A: Incorrect. Noise blankers don't increase bandwidth - they reduce gain, not change bandwidth. Bandwidth stays the same.
Option B: Incorrect. Noise blankers don't redirect pulses into a filter capacitor - they reduce gain during pulses. No redirection involved.
Option D: Incorrect. Noise blankers don't clip noise peaks - they reduce gain during pulses. Clipping is a different technique.
题目解析
The correct answer is C: By reducing receiver gain during a noise pulse. How a noise blanker works is by reducing receiver gain during a noise pulse. When a noise pulse is detected, the receiver gain is momentarily reduced, blanking (removing) the noise. For amateur radio operators, this helps reduce impulse noise interference. Understanding this helps when using noise blankers.
考试技巧
Noise blanker = reduces receiver gain during noise pulse. Think 'N'oise 'B'lanker = 'N'ulls 'B'riefly (reduces gain). When noise pulse detected, receiver gain is momentarily reduced to blank the noise. Not bandwidth increase, not redirection, not clipping - just gain reduction.
记忆口诀
Noise blanker = reduces receiver gain during noise pulse. Think 'N'oise 'B'lanker = 'N'ulls 'B'riefly. When noise pulse detected, receiver gain is momentarily reduced to blank the noise. Effective against impulse noise.
实际应用示例
Impulse noise (like ignition noise) is interfering with your reception. You activate the noise blanker. When a noise pulse is detected, the receiver gain is momentarily reduced, blanking the noise. This allows you to copy signals between noise pulses. Noise blankers are very effective against impulse noise.
错误选项分析
Option A: Incorrect. Noise blankers don't increase bandwidth - they reduce gain, not change bandwidth. Bandwidth stays the same. Option B: Incorrect. Noise blankers don't redirect pulses into a filter capacitor - they reduce gain during pulses. No redirection involved. Option D: Incorrect. Noise blankers don't clip noise peaks - they reduce gain during pulses. Clipping is a different technique.
知识点
Noise blanker, Receiver gain reduction, Noise pulse, Impulse noise
Verified Content
Question from official FCC General Class question pool. Explanation reviewed by licensed amateur radio operators.