Question
Which type of voice mode is often used for long-distance (weak signal) contacts on the VHF and UHF bands?
Answer Options
- A) FM
- B) DRM
- C) SSB
- D) PM
Correct Answer: C
Explanation
For long-distance or weak signal contacts on VHF and UHF bands (such as contacts relying on tropospheric ducting or meteor scatter), Single Sideband (SSB) is the preferred voice mode. SSB is much more efficient and has a significantly narrower bandwidth (\approx 3\text{ kHz}) compared to FM (T8A07/T8A09).
This narrow bandwidth concentrates the available transmitted power into a much smaller slice of the spectrum, improving the signal-to-noise ratio. This concentration of power makes the signal easier to detect and copy when it is extremely weak and fading. FM is generally only usable for strong, line-of-sight signals.
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