What determines the PEP-to-average power ratio of an unprocessed single-sideband phone signal?
The correct answer is B: Speech characteristics. The PEP-to-average power ratio of an unprocessed single-sideband phone signal is determined by speech characteristics - the natural variations in speech amplitude, timing, and content.
Speech has inherent characteristics: vowel sounds are louder (higher amplitude), consonants are quieter, and there are pauses between words. These natural variations in speech amplitude create the PEP-to-average ratio. Different speakers, languages, or speaking styles can produce slightly different ratios, but typical speech gives about a 2.5:1 ratio. The ratio isn't determined by frequency, carrier suppression, or amplifier gain - it's fundamentally about how speech energy is distributed over time.
Exam Tip
PEP ratio determined by = Speech characteristics. Remember: The PEP-to-average power ratio is determined by speech characteristics - the natural amplitude variations in speech (vowels vs consonants, pauses, etc.).
Memory Aid
"**P**EP **R**atio = **S**peech **C**haracteristics (think 'PR = SC')"
Real-World Application
You're transmitting SSB phone. When you say a loud vowel sound, power peaks. When you say a quiet consonant or pause, power drops. These natural speech characteristics create the PEP-to-average ratio. A speaker with more dynamic range (louder peaks, quieter valleys) might have a higher ratio, while someone speaking more evenly might have a lower ratio. The ratio comes from speech itself, not your equipment.
FCC Part 97.313Key Concepts
Why Other Options Are Wrong
Option A: Incorrect. The modulating signal frequency doesn't determine the PEP-to-average ratio. The ratio is about amplitude variations, not frequency content.
Option C: Incorrect. Carrier suppression affects the SSB signal quality but doesn't determine the PEP-to-average ratio. The ratio is about speech amplitude variations.
Option D: Incorrect. Amplifier gain affects output power level but doesn't change the PEP-to-average ratio. The ratio is determined by the speech signal characteristics, not amplifier settings.
题目解析
The correct answer is B: Speech characteristics. The PEP-to-average power ratio of an unprocessed single-sideband phone signal is determined by speech characteristics - the natural variations in speech amplitude, timing, and content. Speech has inherent characteristics: vowel sounds are louder (higher amplitude), consonants are quieter, and there are pauses between words. These natural variations in speech amplitude create the PEP-to-average ratio. Different speakers, languages, or speaking styles can produce slightly different ratios, but typical speech gives about a 2.5:1 ratio. The ratio isn't determined by frequency, carrier suppression, or amplifier gain - it's fundamentally about how speech energy is distributed over time.
考试技巧
PEP ratio determined by = Speech characteristics. Remember: The PEP-to-average power ratio is determined by speech characteristics - the natural amplitude variations in speech (vowels vs consonants, pauses, etc.).
记忆口诀
**P**EP **R**atio = **S**peech **C**haracteristics (think 'PR = SC')
实际应用示例
You're transmitting SSB phone. When you say a loud vowel sound, power peaks. When you say a quiet consonant or pause, power drops. These natural speech characteristics create the PEP-to-average ratio. A speaker with more dynamic range (louder peaks, quieter valleys) might have a higher ratio, while someone speaking more evenly might have a lower ratio. The ratio comes from speech itself, not your equipment.
错误选项分析
Option A: Incorrect. The modulating signal frequency doesn't determine the PEP-to-average ratio. The ratio is about amplitude variations, not frequency content. Option C: Incorrect. Carrier suppression affects the SSB signal quality but doesn't determine the PEP-to-average ratio. The ratio is about speech amplitude variations. Option D: Incorrect. Amplifier gain affects output power level but doesn't change the PEP-to-average ratio. The ratio is determined by the speech signal characteristics, not amplifier settings.
知识点
PEP-to-average ratio, Speech characteristics, SSB phone, Speech amplitude
Verified Content
Question from official FCC Extra Class question pool. Explanation reviewed by licensed amateur radio operators.