← SPECTRA

Signal library

What each radio signal looks like on a waterfall, what it sounds like, and where you'll run into it — 12 modulations, each one synthesised live in the browser.

• Broadcast FM
  A wide, solid block that flickers in width with the loudness of the audio.
• Narrowband FM
  A slim solid bar, keying up and down as people talk.
• AM Voice
  A bright central carrier line flanked by two symmetric audio sidebands.
• SSB (Upper)
  A narrow, ragged band with no carrier line, only on one side of the tuned point.
• SSB (Lower)
  A narrow ragged band with no carrier line, on the lower side of the tuned point.
• CW / Morse
  A single hair-thin line blinking on and off in dot/dash rhythm.
• 2-FSK Data
  Two parallel rails that light up together in short bursts.
• OOK / ASK
  A single line stuttering in fast irregular bursts (a packet).
• LoRa (CSS)
  Unmistakable diagonal sawtooth ramps sweeping across the channel. The ramp's width is the channel bandwidth and its rate gives the spreading factor; tap one and the receiver reads both.
• PSK Burst
  A flat-topped rectangular block that appears and vanishes as frames pass.
• Freq Hopper
  Scattered short dashes sprinkled unpredictably across the whole span.
• Pulsed Radar
  A bright wide line strobing at a steady pulse-repetition rhythm.

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