E8A07: PEP-to-average ratio: What determines the PEP-to-average power

Q: What determines the PEP-to-average power ratio of an unprocessed single-sideband phone signal?

The correct answer is B: Speech characteristics. 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.

Updated: Dec 9, 2025 | Source: 2024-2028 Question Pool | Topic: E8A

E8A07E8A

What determines the PEP-to-average power ratio of an unprocessed single-sideband phone signal?

Previous Next

Deep Dive: E8A07

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.

Why Other Answers 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.

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 Example

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.

Source & Coverage

Question Pool: 2024-2028 Question Pool

Subelement: E8A

Reference: FCC Part 97.313

Key Concepts

PEP-to-average ratio Speech characteristics SSB phone Speech amplitude

Verified Content

Question from the official FCC Extra Class pool. Explanation reviewed by licensed amateur radio operators and mapped to the E8A topic.