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SESK: Stuff Everyone Should Know · sesk.info/ham-dtmf-two-tones

What type of repeater signaling uses two audio tones at the same time?

DTMF, the touch-tone keypad sounds.

  1. DTMF ✔
  2. CTCSS
  3. D-STAR

Why: DTMF means dual-tone multi-frequency. Each keypad button sends two tones at once, just like a telephone keypad.

Huh, didn't know that: DTMF tones are how you reach Internet Radio Linking Project (IRLP) nodes over the air.

The dad joke
Why did the ham dial so happily? Every button had two tones of fun.
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Sources

  1. NCVEC 2026-2030 Technician Question Pool (Element 2), errata Feb 19, 2026 https://www.ncvec.org/downloads/2026-2030%20Technician%20Pool%20and%20Syllabus%20Public%20Release%20Feb%2019%202026.pdf

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