What is the effect of modulation duty cycle on RF exposure?
The correct answer is A: A lower duty cycle permits greater power levels to be transmitted. The effect of modulation duty cycle on RF exposure is that a lower duty cycle permits greater power levels to be transmitted. Lower duty cycle means less average power, so you can use higher peak power while staying within exposure limits. For amateur radio operators, this is important for high-power operation. Understanding this helps optimize power levels.
Exam Tip
Duty cycle effect on RF exposure = lower duty cycle permits greater power. Think 'L'ower 'D'uty 'C'ycle = 'L'ess average power = 'G'reater peak power allowed. Lower duty cycle means less average power, so higher peak power is allowed. Not higher duty cycle, not exemption - just lower duty cycle permits greater power.
Memory Aid
"Duty cycle effect on RF exposure = lower duty cycle permits greater power. Think 'L'ower 'D'uty 'C'ycle = 'G'reater power. Lower duty cycle means less average power, so higher peak power is allowed. Important for high-power operation."
Real-World Application
Modulation duty cycle: CW has low duty cycle (~50%), so you can use higher peak power while staying within RF exposure limits. SSB has higher duty cycle (~100% when talking), so average power is higher, limiting peak power. Lower duty cycle permits greater power levels - this is the effect on RF exposure.
FCC Part 97.13Key Concepts
Why Other Options Are Wrong
Option B: Incorrect. Higher duty cycle doesn't permit greater power - lower duty cycle permits greater power because average power is lower. Higher duty cycle is wrong.
Option C: Incorrect. Low duty cycle transmitters aren't exempt from evaluation - they still need evaluation, though they may qualify for exemption. Exemption isn't automatic.
Option D: Incorrect. High duty cycle transmitters aren't exempt - they need evaluation. Exemption isn't automatic.
题目解析
The correct answer is A: A lower duty cycle permits greater power levels to be transmitted. The effect of modulation duty cycle on RF exposure is that a lower duty cycle permits greater power levels to be transmitted. Lower duty cycle means less average power, so you can use higher peak power while staying within exposure limits. For amateur radio operators, this is important for high-power operation. Understanding this helps optimize power levels.
考试技巧
Duty cycle effect on RF exposure = lower duty cycle permits greater power. Think 'L'ower 'D'uty 'C'ycle = 'L'ess average power = 'G'reater peak power allowed. Lower duty cycle means less average power, so higher peak power is allowed. Not higher duty cycle, not exemption - just lower duty cycle permits greater power.
记忆口诀
Duty cycle effect on RF exposure = lower duty cycle permits greater power. Think 'L'ower 'D'uty 'C'ycle = 'G'reater power. Lower duty cycle means less average power, so higher peak power is allowed. Important for high-power operation.
实际应用示例
Modulation duty cycle: CW has low duty cycle (~50%), so you can use higher peak power while staying within RF exposure limits. SSB has higher duty cycle (~100% when talking), so average power is higher, limiting peak power. Lower duty cycle permits greater power levels - this is the effect on RF exposure.
错误选项分析
Option B: Incorrect. Higher duty cycle doesn't permit greater power - lower duty cycle permits greater power because average power is lower. Higher duty cycle is wrong. Option C: Incorrect. Low duty cycle transmitters aren't exempt from evaluation - they still need evaluation, though they may qualify for exemption. Exemption isn't automatic. Option D: Incorrect. High duty cycle transmitters aren't exempt - they need evaluation. Exemption isn't automatic.
知识点
Modulation duty cycle, RF exposure, Lower duty cycle, Greater power levels
Verified Content
Question from official FCC General Class question pool. Explanation reviewed by licensed amateur radio operators.