Which mode of voice communication is most commonly used on the HF amateur bands?
The correct answer is C: Single sideband. Single sideband (SSB) is the most commonly used mode for voice communication on the HF amateur bands. SSB is more efficient than AM (uses less bandwidth and power) and is better suited for HF than FM (which requires more bandwidth). For amateur radio operators, SSB is the standard voice mode on HF. Understanding this helps when planning HF voice operations. SSB dominates HF voice communications.
Exam Tip
HF voice mode = Single sideband. Think 'S'ingle 'S'ideband = 'S'tandard for 'S'peech on HF. Most commonly used voice mode on HF amateur bands. FM is for VHF/UHF, DSB is inefficient, PM isn't common.
Memory Aid
"HF voice mode = Single sideband. Think 'S'ingle 'S'ideband = 'S'tandard for HF. Most commonly used voice mode on HF amateur bands. Efficient and well-suited for HF propagation."
Real-World Application
You want to make voice contacts on 20 meters. You use SSB (single sideband) - it's what everyone uses for HF voice. SSB is efficient (uses 3 kHz bandwidth vs 6 kHz for AM), puts all power into the sideband (no carrier), and works well with HF propagation. It's the dominant voice mode on HF.
Key Concepts
Why Other Options Are Wrong
Option A (Frequency modulation): Incorrect. FM is used on VHF/UHF, not commonly on HF. FM requires more bandwidth and isn't well-suited for HF propagation.
Option B (Double sideband): Incorrect. DSB (full AM) is inefficient and rarely used. SSB is much more common on HF.
Option D (Single phase modulation): Incorrect. This isn't a real mode - phase modulation (PM) exists but isn't commonly used for HF voice. SSB is the standard.
题目解析
The correct answer is C: Single sideband. Single sideband (SSB) is the most commonly used mode for voice communication on the HF amateur bands. SSB is more efficient than AM (uses less bandwidth and power) and is better suited for HF than FM (which requires more bandwidth). For amateur radio operators, SSB is the standard voice mode on HF. Understanding this helps when planning HF voice operations. SSB dominates HF voice communications.
考试技巧
HF voice mode = Single sideband. Think 'S'ingle 'S'ideband = 'S'tandard for 'S'peech on HF. Most commonly used voice mode on HF amateur bands. FM is for VHF/UHF, DSB is inefficient, PM isn't common.
记忆口诀
HF voice mode = Single sideband. Think 'S'ingle 'S'ideband = 'S'tandard for HF. Most commonly used voice mode on HF amateur bands. Efficient and well-suited for HF propagation.
实际应用示例
You want to make voice contacts on 20 meters. You use SSB (single sideband) - it's what everyone uses for HF voice. SSB is efficient (uses 3 kHz bandwidth vs 6 kHz for AM), puts all power into the sideband (no carrier), and works well with HF propagation. It's the dominant voice mode on HF.
错误选项分析
Option A (Frequency modulation): Incorrect. FM is used on VHF/UHF, not commonly on HF. FM requires more bandwidth and isn't well-suited for HF propagation. Option B (Double sideband): Incorrect. DSB (full AM) is inefficient and rarely used. SSB is much more common on HF. Option D (Single phase modulation): Incorrect. This isn't a real mode - phase modulation (PM) exists but isn't commonly used for HF voice. SSB is the standard.
知识点
Single sideband, SSB, HF voice mode, Voice communications
Verified Content
Question from official FCC General Class question pool. Explanation reviewed by licensed amateur radio operators.