Which mode is most commonly used for voice communications on the 17- and 12-meter bands?
The correct answer is A: Upper sideband. Upper sideband (USB) is most commonly used for voice communications on the 17- and 12-meter bands. These bands are above 10 MHz (17m is ~18 MHz, 12m is ~24 MHz), so USB is the standard convention. For amateur radio operators, understanding this ensures compatibility. Everyone uses USB on these bands, allowing proper communication. This is consistent with the convention for frequencies above 10 MHz.
Exam Tip
17m, 12m = Upper sideband. Think 'U'pper 'S'ideband for 'U'pper frequencies. 17m (~18 MHz) and 12m (~24 MHz) are above 10 MHz, so USB is standard. LSB is for lower frequencies (below 10 MHz).
Memory Aid
"17m, 12m = Upper sideband. Think 'U'pper 'S'ideband for 'U'pper frequencies. 17m and 12m are above 10 MHz, so USB is standard. LSB is for 160m, 80m, 40m (below 10 MHz)."
Real-World Application
You operate SSB on 17 meters (18 MHz). Everyone uses upper sideband on this band - it's the standard convention. If you transmitted lower sideband, your signal would be on the wrong side of the carrier, and other operators wouldn't be able to copy you properly. USB ensures compatibility on 17m and 12m.
Key Concepts
Why Other Options Are Wrong
Option B (Lower sideband): Incorrect. LSB is used on frequencies below 10 MHz (160m, 80m, 40m), not on 17m and 12m. USB is standard above 10 MHz.
Option C (Suppressed sideband): Incorrect. This describes the technique, not which sideband is used. Both USB and LSB are suppressed sideband modes.
Option D (Double sideband): Incorrect. DSB transmits both sidebands, which is inefficient. SSB (single sideband) is standard, and USB is used on 17m and 12m.
题目解析
The correct answer is A: Upper sideband. Upper sideband (USB) is most commonly used for voice communications on the 17- and 12-meter bands. These bands are above 10 MHz (17m is ~18 MHz, 12m is ~24 MHz), so USB is the standard convention. For amateur radio operators, understanding this ensures compatibility. Everyone uses USB on these bands, allowing proper communication. This is consistent with the convention for frequencies above 10 MHz.
考试技巧
17m, 12m = Upper sideband. Think 'U'pper 'S'ideband for 'U'pper frequencies. 17m (~18 MHz) and 12m (~24 MHz) are above 10 MHz, so USB is standard. LSB is for lower frequencies (below 10 MHz).
记忆口诀
17m, 12m = Upper sideband. Think 'U'pper 'S'ideband for 'U'pper frequencies. 17m and 12m are above 10 MHz, so USB is standard. LSB is for 160m, 80m, 40m (below 10 MHz).
实际应用示例
You operate SSB on 17 meters (18 MHz). Everyone uses upper sideband on this band - it's the standard convention. If you transmitted lower sideband, your signal would be on the wrong side of the carrier, and other operators wouldn't be able to copy you properly. USB ensures compatibility on 17m and 12m.
错误选项分析
Option B (Lower sideband): Incorrect. LSB is used on frequencies below 10 MHz (160m, 80m, 40m), not on 17m and 12m. USB is standard above 10 MHz. Option C (Suppressed sideband): Incorrect. This describes the technique, not which sideband is used. Both USB and LSB are suppressed sideband modes. Option D (Double sideband): Incorrect. DSB transmits both sidebands, which is inefficient. SSB (single sideband) is standard, and USB is used on 17m and 12m.
知识点
Upper sideband, USB, 17m, 12m, SSB conventions
Verified Content
Question from official FCC General Class question pool. Explanation reviewed by licensed amateur radio operators.