When using a transceiver that displays the carrier frequency of phone signals, which of the following displayed frequencies represents the lowest frequency at which a properly adjusted LSB emission will be totally within the band?
The correct answer is D: 3 kHz above the lower band edge. When using a transceiver that displays the carrier frequency of phone signals, the displayed frequency that represents the lowest frequency at which a properly adjusted LSB emission will be totally within the band is 3 kHz above the lower band edge. LSB extends 3 kHz below the carrier, so carrier must be at least 3 kHz above lower band edge. For amateur radio operators, this is important for band compliance. Understanding this helps ensure legal operation.
Exam Tip
LSB carrier minimum = 3 kHz above lower band edge. Think 'L'SB = 'L'ower 'S'ideband extends '3' kHz below carrier. LSB extends 3 kHz below carrier, so carrier must be at least 3 kHz above lower band edge. Not exact edge, not 300 Hz, not 1 kHz - just 3 kHz above.
Memory Aid
"LSB carrier minimum = 3 kHz above lower band edge. Think 'L'SB = '3' kHz below carrier. LSB extends 3 kHz below carrier, so carrier must be at least 3 kHz above lower band edge. Important for band compliance."
Real-World Application
A properly adjusted LSB emission: The lower sideband extends 3 kHz below the carrier frequency. If the lower band edge is 3.800 MHz, the carrier must be at least 3.803 MHz (3 kHz above) so the lower sideband (down to 3.800 MHz) stays within the band. 3 kHz above the lower band edge is the minimum carrier frequency for LSB.
FCC Part 97.301Key Concepts
Why Other Options Are Wrong
Option A: Incorrect. Exact lower band edge isn't enough - LSB extends 3 kHz below carrier, so carrier must be 3 kHz above edge. Exact edge is too low.
Option B: Incorrect. 300 Hz above isn't enough - LSB extends 3 kHz below carrier, so carrier must be 3 kHz above edge. 300 Hz is too low.
Option C: Incorrect. 1 kHz above isn't enough - LSB extends 3 kHz below carrier, so carrier must be 3 kHz above edge. 1 kHz is too low.
题目解析
The correct answer is D: 3 kHz above the lower band edge. When using a transceiver that displays the carrier frequency of phone signals, the displayed frequency that represents the lowest frequency at which a properly adjusted LSB emission will be totally within the band is 3 kHz above the lower band edge. LSB extends 3 kHz below the carrier, so carrier must be at least 3 kHz above lower band edge. For amateur radio operators, this is important for band compliance. Understanding this helps ensure legal operation.
考试技巧
LSB carrier minimum = 3 kHz above lower band edge. Think 'L'SB = 'L'ower 'S'ideband extends '3' kHz below carrier. LSB extends 3 kHz below carrier, so carrier must be at least 3 kHz above lower band edge. Not exact edge, not 300 Hz, not 1 kHz - just 3 kHz above.
记忆口诀
LSB carrier minimum = 3 kHz above lower band edge. Think 'L'SB = '3' kHz below carrier. LSB extends 3 kHz below carrier, so carrier must be at least 3 kHz above lower band edge. Important for band compliance.
实际应用示例
A properly adjusted LSB emission: The lower sideband extends 3 kHz below the carrier frequency. If the lower band edge is 3.800 MHz, the carrier must be at least 3.803 MHz (3 kHz above) so the lower sideband (down to 3.800 MHz) stays within the band. 3 kHz above the lower band edge is the minimum carrier frequency for LSB.
错误选项分析
Option A: Incorrect. Exact lower band edge isn't enough - LSB extends 3 kHz below carrier, so carrier must be 3 kHz above edge. Exact edge is too low. Option B: Incorrect. 300 Hz above isn't enough - LSB extends 3 kHz below carrier, so carrier must be 3 kHz above edge. 300 Hz is too low. Option C: Incorrect. 1 kHz above isn't enough - LSB extends 3 kHz below carrier, so carrier must be 3 kHz above edge. 1 kHz is too low.
知识点
LSB emission, Carrier frequency, 3 kHz above lower band edge, Band compliance
Verified Content
Question from official FCC Extra Class question pool. Explanation reviewed by licensed amateur radio operators.