What is the highest modulation index permitted at the highest modulation frequency for angle modulation below 29.0 MHz?
The correct answer is B: 1.0. The highest modulation index permitted at the highest modulation frequency for angle modulation below 29.0 MHz is 1.0. Angle modulation (FM/PM) below 29 MHz is limited to a modulation index of 1.0. For amateur radio operators, this is important for HF operation. Understanding this helps ensure legal operation.
Exam Tip
Angle modulation below 29 MHz = maximum modulation index 1.0. Think 'A'ngle 'M'odulation 'B'elow '2'9 MHz = '1'.0 maximum. Angle modulation below 29 MHz is limited to modulation index of 1.0. Not 0.5, not 2.0, not 3.0 - just 1.0.
Memory Aid
"Angle modulation below 29 MHz = maximum modulation index 1.0. Think 'A'ngle 'M'odulation = '1'.0 maximum. Angle modulation below 29 MHz is limited to modulation index of 1.0. Important for HF operation."
Real-World Application
Angle modulation (FM/PM) below 29.0 MHz: The highest modulation index permitted at the highest modulation frequency is 1.0. This limits the frequency deviation or phase deviation to prevent excessive bandwidth. For example, with 3 kHz modulating frequency, maximum deviation would be 3 kHz (modulation index = deviation/modulating frequency = 3/3 = 1.0). 1.0 is the maximum modulation index.
FCC Part 97.307Key Concepts
Why Other Options Are Wrong
Option A (0.5): Incorrect. 0.5 is too low - the maximum is 1.0, not 0.5. 0.5 is too restrictive.
Option C (2.0): Incorrect. 2.0 is too high - the maximum is 1.0, not 2.0. 2.0 exceeds the limit.
Option D (3.0): Incorrect. 3.0 is way too high - the maximum is 1.0, not 3.0. 3.0 exceeds the limit.
题目解析
The correct answer is B: 1.0. The highest modulation index permitted at the highest modulation frequency for angle modulation below 29.0 MHz is 1.0. Angle modulation (FM/PM) below 29 MHz is limited to a modulation index of 1.0. For amateur radio operators, this is important for HF operation. Understanding this helps ensure legal operation.
考试技巧
Angle modulation below 29 MHz = maximum modulation index 1.0. Think 'A'ngle 'M'odulation 'B'elow '2'9 MHz = '1'.0 maximum. Angle modulation below 29 MHz is limited to modulation index of 1.0. Not 0.5, not 2.0, not 3.0 - just 1.0.
记忆口诀
Angle modulation below 29 MHz = maximum modulation index 1.0. Think 'A'ngle 'M'odulation = '1'.0 maximum. Angle modulation below 29 MHz is limited to modulation index of 1.0. Important for HF operation.
实际应用示例
Angle modulation (FM/PM) below 29.0 MHz: The highest modulation index permitted at the highest modulation frequency is 1.0. This limits the frequency deviation or phase deviation to prevent excessive bandwidth. For example, with 3 kHz modulating frequency, maximum deviation would be 3 kHz (modulation index = deviation/modulating frequency = 3/3 = 1.0). 1.0 is the maximum modulation index.
错误选项分析
Option A (0.5): Incorrect. 0.5 is too low - the maximum is 1.0, not 0.5. 0.5 is too restrictive. Option C (2.0): Incorrect. 2.0 is too high - the maximum is 1.0, not 2.0. 2.0 exceeds the limit. Option D (3.0): Incorrect. 3.0 is way too high - the maximum is 1.0, not 3.0. 3.0 exceeds the limit.
知识点
Angle modulation, Below 29.0 MHz, Modulation index, 1.0
Verified Content
Question from official FCC Extra Class question pool. Explanation reviewed by licensed amateur radio operators.