Science · 6 pages · 12 min
How radio waves carry a signal
A steady radio wave is only a carrier, and the signal is a deliberate change in that wave.
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From the opening
Radio waves carry a signal because a transmitter varies a high-frequency electromagnetic wave in step with the message. The wave travels, and a receiver tuned to it undoes the variation and recovers the sound, the bits, or the picture. The opening covers a carrier varied by the message, tuning as choosing one frequency, and sidebands are the message footprint.
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Inside
- A carrier varied by the message
- Tuning as choosing one frequency
- Sidebands are the message footprint
- Why a steady tone carries nothing
- Where the idea stops applying
- A distinction worth keeping
Sources
- Carrier modulation and demodulation
- Sidebands around a radio-frequency carrier