Question
Which of the following phone emissions uses the narrowest bandwidth?
Answer Options
- A) Single sideband
- B) Vestigial sideband
- C) Phase modulation
- D) Frequency modulation
Correct Answer: A
Explanation
The bandwidth of a voice (phone) signal determines how many other signals can fit into a given portion of the spectrum. Standard Amplitude Modulation (AM) uses two sidebands plus a carrier, requiring about 6 \text{ kHz} of bandwidth. Frequency Modulation (FM) typically requires a wider band, often 5 \text{ kHz} or more, depending on deviation.
Single sideband (SSB) achieves the narrowest bandwidth by removing the carrier and one of the sidebands, leaving only the information contained in the single remaining sideband. This results in a bandwidth of approximately 3 \text{ kHz} (sometimes less), making it the most spectrally efficient analog voice mode.
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