How does a signal that reads 20 dB over S9 compare to one that reads S9 on a receiver, assuming a properly calibrated S meter?
The correct answer is D: It is 100 times more powerful. How a signal that reads 20 dB over S9 compares to one that reads S9 on a properly calibrated S meter is that it is 100 times more powerful. Each 10 dB represents a 10:1 power ratio, so 20 dB represents 100:1 (10 × 10). For amateur radio operators, this helps understand S meter readings. Understanding this helps when comparing signals.
Exam Tip
20 dB over S9 vs S9 = 100 times more powerful. Think '2'0 dB = '2' × '1'0 dB = '1'00:1 power ratio. Each 10 dB represents 10:1 power ratio, so 20 dB represents 100:1. Not 10 or 20 times - 100 times.
Memory Aid
"20 dB over S9 vs S9 = 100 times more powerful. Think '2'0 dB = '2' × '1'0 dB = '1'00:1. Each 10 dB represents 10:1 power ratio, so 20 dB represents 100:1. Significant power difference."
Real-World Application
Signal A reads S9, Signal B reads S9+20 dB. Signal B is 100 times more powerful than Signal A. Each 10 dB represents a 10:1 power ratio (10 dB = 10×, 20 dB = 100×). This is a huge difference in signal strength.
Key Concepts
Why Other Options Are Wrong
Option A: Incorrect. 10 times less powerful is wrong - 20 dB over S9 is more powerful, not less. The signal is stronger, not weaker.
Option B: Incorrect. 20 times less powerful is wrong - 20 dB over S9 is more powerful. The signal is stronger, not weaker.
Option C: Incorrect. 20 times more powerful is wrong - 20 dB represents 100:1 power ratio, not 20:1. Each 10 dB is 10:1, so 20 dB is 100:1.
题目解析
The correct answer is D: It is 100 times more powerful. How a signal that reads 20 dB over S9 compares to one that reads S9 on a properly calibrated S meter is that it is 100 times more powerful. Each 10 dB represents a 10:1 power ratio, so 20 dB represents 100:1 (10 × 10). For amateur radio operators, this helps understand S meter readings. Understanding this helps when comparing signals.
考试技巧
20 dB over S9 vs S9 = 100 times more powerful. Think '2'0 dB = '2' × '1'0 dB = '1'00:1 power ratio. Each 10 dB represents 10:1 power ratio, so 20 dB represents 100:1. Not 10 or 20 times - 100 times.
记忆口诀
20 dB over S9 vs S9 = 100 times more powerful. Think '2'0 dB = '2' × '1'0 dB = '1'00:1. Each 10 dB represents 10:1 power ratio, so 20 dB represents 100:1. Significant power difference.
实际应用示例
Signal A reads S9, Signal B reads S9+20 dB. Signal B is 100 times more powerful than Signal A. Each 10 dB represents a 10:1 power ratio (10 dB = 10×, 20 dB = 100×). This is a huge difference in signal strength.
错误选项分析
Option A: Incorrect. 10 times less powerful is wrong - 20 dB over S9 is more powerful, not less. The signal is stronger, not weaker. Option B: Incorrect. 20 times less powerful is wrong - 20 dB over S9 is more powerful. The signal is stronger, not weaker. Option C: Incorrect. 20 times more powerful is wrong - 20 dB represents 100:1 power ratio, not 20:1. Each 10 dB is 10:1, so 20 dB is 100:1.
知识点
S meter, 20 dB over S9, Power ratio, Signal comparison
Verified Content
Question from official FCC General Class question pool. Explanation reviewed by licensed amateur radio operators.