Deep Dive: G8A07
The correct answer is A: Single sideband. The phone emission that uses the narrowest bandwidth is single sideband. SSB uses only one sideband (typically 2.4-3 kHz), making it the narrowest bandwidth phone mode. For amateur radio operators, this is why SSB is popular on HF. Understanding this helps when selecting operating modes.
Why Other Answers Are Wrong
Option B (Vestigial sideband): Incorrect. Vestigial sideband is wider than SSB - it includes part of the other sideband, making it wider. VSB isn't the narrowest. Option C (Phase modulation): Incorrect. Phase modulation is wider than SSB - PM typically uses more bandwidth than SSB. PM isn't the narrowest. Option D (Frequency modulation): Incorrect. Frequency modulation is much wider than SSB - FM typically uses 5-15 kHz, much wider than SSB. FM isn't the narrowest.
Exam Tip
Narrowest bandwidth phone emission = single sideband. Think 'S'SB = 'S'ingle 'S'ideband = 'S'limmest bandwidth. SSB uses only one sideband (2.4-3 kHz), making it narrowest. Not vestigial sideband, not phase modulation, not frequency modulation - just SSB.
Memory Aid
Narrowest bandwidth phone emission = single sideband. Think 'S'SB = 'S'limmest bandwidth. SSB uses only one sideband (2.4-3 kHz), making it narrowest. Most efficient phone mode for HF.
Real-World Example
Phone emissions bandwidth comparison: SSB uses 2.4-3 kHz (narrowest), vestigial sideband uses more, phase modulation uses more, FM uses 5-15 kHz (widest). SSB's narrow bandwidth makes it efficient for HF operation, allowing more stations in the same spectrum. SSB is the narrowest bandwidth phone emission.
Source & Coverage
Question Pool: 2023-2027 Question Pool
Subelement: G8A
Reference: 2023-2027 Question Pool · G8 - Signals and Emissions
Key Concepts
Verified Content
Question from the official FCC General Class pool. Explanation reviewed by licensed amateur radio operators and mapped to the G8A topic.