What is a characteristic of HF scatter?
The correct answer is B: Signals have a fluttering sound. A characteristic of HF scatter is that signals have a fluttering sound. Scatter signals are created by multiple reflection paths, causing rapid signal variations that sound like fluttering. For amateur radio operators, this distinctive sound helps identify scatter propagation. Understanding this helps recognize scatter signals.
Exam Tip
HF scatter characteristic = fluttering sound. Think 'S'catter = 'S'ignal 'S'cattered = 'S'ound 'S'cattered (fluttering). Signals have rapid variations from multiple reflection paths, creating fluttering sound. Not high intelligibility, not large swings, not night-only - just fluttering.
Memory Aid
"HF scatter characteristic = fluttering sound. Think 'S'catter = 'S'ignal 'S'cattered = 'S'ound 'S'cattered. Signals have rapid variations from multiple reflection paths, creating distinctive fluttering sound. Key identifier of scatter propagation."
Real-World Application
You receive an HF scatter signal. It has a distinctive fluttering sound - rapid, small variations in signal strength caused by multiple reflection paths. The signal may be weak and distorted, but the fluttering characteristic identifies it as scatter propagation. This is different from normal skywave signals.
Key Concepts
Why Other Options Are Wrong
Option A: Incorrect. Scatter signals don't have high intelligibility - they're often distorted and hard to copy. High intelligibility isn't a scatter characteristic.
Option C: Incorrect. Scatter signals don't have very large, sudden swings - they have rapid, small variations (fluttering), not large swings. Fluttering is the key characteristic.
Option D: Incorrect. Scatter propagation doesn't occur only at night - it can occur at any time. Time isn't the defining characteristic.
题目解析
The correct answer is B: Signals have a fluttering sound. A characteristic of HF scatter is that signals have a fluttering sound. Scatter signals are created by multiple reflection paths, causing rapid signal variations that sound like fluttering. For amateur radio operators, this distinctive sound helps identify scatter propagation. Understanding this helps recognize scatter signals.
考试技巧
HF scatter characteristic = fluttering sound. Think 'S'catter = 'S'ignal 'S'cattered = 'S'ound 'S'cattered (fluttering). Signals have rapid variations from multiple reflection paths, creating fluttering sound. Not high intelligibility, not large swings, not night-only - just fluttering.
记忆口诀
HF scatter characteristic = fluttering sound. Think 'S'catter = 'S'ignal 'S'cattered = 'S'ound 'S'cattered. Signals have rapid variations from multiple reflection paths, creating distinctive fluttering sound. Key identifier of scatter propagation.
实际应用示例
You receive an HF scatter signal. It has a distinctive fluttering sound - rapid, small variations in signal strength caused by multiple reflection paths. The signal may be weak and distorted, but the fluttering characteristic identifies it as scatter propagation. This is different from normal skywave signals.
错误选项分析
Option A: Incorrect. Scatter signals don't have high intelligibility - they're often distorted and hard to copy. High intelligibility isn't a scatter characteristic. Option C: Incorrect. Scatter signals don't have very large, sudden swings - they have rapid, small variations (fluttering), not large swings. Fluttering is the key characteristic. Option D: Incorrect. Scatter propagation doesn't occur only at night - it can occur at any time. Time isn't the defining characteristic.
知识点
HF scatter, Fluttering sound, Scatter propagation, Signal characteristics
Verified Content
Question from official FCC General Class question pool. Explanation reviewed by licensed amateur radio operators.