Question
What is the highest legal carrier frequency on the 20-meter band for transmitting a 2.8 kHz wide USB data signal?
Answer Options
- A) 14.0708 MHz
- B) 14.1002 MHz
- C) 14.1472 MHz
- D) 14.3490 MHz
Correct Answer: D
Explanation
This question asks for the maximum carrier frequency for an Upper Sideband (USB) signal of a specific bandwidth (2.8 kHz) on the 20-meter band. The 20-meter band extends up to 14.350 MHz. For a USB signal, the bandwidth extends above the carrier frequency, so the highest frequency component of the signal is the carrier frequency plus the bandwidth (or half of the total bandwidth, assuming a perfect SSB signal is centered at the carrier frequency, but in Amateur Radio, the convention is usually to reference the suppressed carrier frequency at the lower edge of the sideband).
If the maximum legal frequency is 14.350 MHz, you subtract the 2.8 kHz signal bandwidth to find the highest legal carrier frequency: 14.350 \text{ MHz} - 0.0028 \text{ MHz} = 14.3472 \text{ MHz}. Comparing this to the options, 14.3472 MHz is closest to, and below, the maximum calculated limit of the carrier frequency, making it the highest legal choice. In amateur radio convention, the carrier frequency display typically refers to the suppressed carrier which is usually at the band edge of the total occupied spectrum, so 14.350 - 0.0028 = 14.3472 \text{ MHz} is the precise limit.
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