What characterizes libration fading of an EME signal?
The correct answer is B: A fluttery, irregular fading. What characterizes libration fading of an EME signal is a fluttery, irregular fading. Libration fading is caused by the moon's slight wobbling motion. For amateur radio operators, this is important for EME operation. Understanding this helps when operating EME.
Exam Tip
Libration fading = fluttery, irregular fading. Think 'L'ibration 'F'ading = 'L'ight 'F'luttery fading. Libration fading is caused by the moon's slight wobbling motion, creating fluttery, irregular fading. Not pitch change, not sunrise loss, not frequency shift - just fluttery, irregular fading.
Memory Aid
"Libration fading = fluttery, irregular fading. Think 'L'ibration 'F'ading = 'F'luttery. Libration fading is caused by the moon's slight wobbling motion, creating fluttery, irregular fading. Important for EME operation."
Real-World Application
Libration fading in EME signals: It's characterized by a fluttery, irregular fading pattern. This is caused by the moon's slight wobbling motion (libration), which causes the signal path to vary slightly. The fading is rapid and irregular, not smooth. This is what libration fading is - fluttery, irregular fading.
Key Concepts
Why Other Options Are Wrong
Option A: Incorrect. Slow change in pitch of CW signal isn't libration fading - libration fading is fluttery, irregular fading. Pitch change isn't libration fading.
Option C: Incorrect. Gradual loss of signal as sun rises isn't libration fading - libration fading is fluttery, irregular fading. Sunrise loss isn't libration fading.
Option D: Incorrect. Returning echo several hertz lower isn't libration fading - libration fading is fluttery, irregular fading. Frequency shift isn't libration fading.
题目解析
The correct answer is B: A fluttery, irregular fading. What characterizes libration fading of an EME signal is a fluttery, irregular fading. Libration fading is caused by the moon's slight wobbling motion. For amateur radio operators, this is important for EME operation. Understanding this helps when operating EME.
考试技巧
Libration fading = fluttery, irregular fading. Think 'L'ibration 'F'ading = 'L'ight 'F'luttery fading. Libration fading is caused by the moon's slight wobbling motion, creating fluttery, irregular fading. Not pitch change, not sunrise loss, not frequency shift - just fluttery, irregular fading.
记忆口诀
Libration fading = fluttery, irregular fading. Think 'L'ibration 'F'ading = 'F'luttery. Libration fading is caused by the moon's slight wobbling motion, creating fluttery, irregular fading. Important for EME operation.
实际应用示例
Libration fading in EME signals: It's characterized by a fluttery, irregular fading pattern. This is caused by the moon's slight wobbling motion (libration), which causes the signal path to vary slightly. The fading is rapid and irregular, not smooth. This is what libration fading is - fluttery, irregular fading.
错误选项分析
Option A: Incorrect. Slow change in pitch of CW signal isn't libration fading - libration fading is fluttery, irregular fading. Pitch change isn't libration fading. Option C: Incorrect. Gradual loss of signal as sun rises isn't libration fading - libration fading is fluttery, irregular fading. Sunrise loss isn't libration fading. Option D: Incorrect. Returning echo several hertz lower isn't libration fading - libration fading is fluttery, irregular fading. Frequency shift isn't libration fading.
知识点
Libration fading, EME signal, Fluttery, irregular fading, Moon libration
Verified Content
Question from official FCC Extra Class question pool. Explanation reviewed by licensed amateur radio operators.