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AhaBulb: Stuff Everyone Should Know · ahabulb.com/ham-ctcss-tone

What is the sub-audible tone sent with your voice to open a repeater's squelch called?

CTCSS, a sub-audible tone under your voice.

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  1. DTMF
  2. Carrier squelch
  3. CTCSS ✔

Why: CTCSS is a low tone sent under your voice. The repeater only opens when it hears the right tone, which keeps out unwanted signals.

Huh, didn't know that: CTCSS stands for Continuous Tone-Coded Squelch System.

The dad joke
The repeater would not let me in. I guess I had the wrong tone.
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References

Answer: CTCSS. CTCSS is a low tone sent under your voice. The repeater only opens when it hears the right tone, which keeps out unwanted signals.

  1. HamStudy 2026-2030 Technician pool, section T2B hamstudy.org/browse/E2_2026/T2B
    CTCSS stands for Continuous Tone-Coded Squelch System.
    Checked 2026-10-09.

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