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Modulation and modes — edited Aug 31, 2026 by Unknown editor
This is the first recorded version, so every line is shown as added. Note: Imported from content/wiki
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## The basic families
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- **CW** — the carrier keyed on and off. Occupies about 100 Hz, and the most power-efficient mode in
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common use.
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- **AM** — amplitude modulation; carrier plus two sidebands, about 6 kHz wide. Mostly nostalgia and
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aviation now.
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- **SSB** — single sideband: one sideband, no carrier. About 2.7 kHz wide, and roughly 8 dB more
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effective than AM for the same peak power. The standard for HF voice.
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- **FM** — frequency modulation, 10–16 kHz wide. Immune to amplitude noise and excellent audio, but
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needs a strong signal — hence the sharp "full quieting or nothing" behavior on repeaters.
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- **Digital** — see [digital modes](/wiki/operating/digital-modes).
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## Bandwidth versus robustness
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Narrow modes concentrate power and get through noise; wide modes sound better when the signal is
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strong. That trade-off explains the entire mode landscape: CW and FT8 for marginal paths, SSB for
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normal HF work, FM for strong local signals.
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## Sideband convention
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Lower sideband below 10 MHz, upper sideband above it, and always USB on VHF/UHF and 60 m. Convention,
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not regulation, but universally followed.
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## Signal quality
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- **Splatter** comes from overdriving; watch ALC and speech processor levels.
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- **Key clicks** come from too-abrupt CW keying envelopes.
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- **Overdriven digital** is the most common modern offence — turn the drive down until ALC barely
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moves.