Morse Code
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Morse code encodes text as dots (·) and dashes (—). A dot = 1 unit; dash = 3 units; letter gap = 3 units; word gap = 7 units.
The signal canvas shows the keyed waveform. The spectrum shows the FFT magnitude — energy concentrates at the carrier with sidebands from the keying envelope.
Shannon bandwidth ≈ 2 × keying rate.