Question
What type of signaling uses pairs of audio tones?
Answer Options
- A) DTMF
- B) CTCSS
- C) GPRS
- D) D-STAR
Correct Answer: A
Explanation
The signaling method that uses pairs of audio tones is DTMF (Dual-Tone Multi-Frequency). You interact with DTMF every time you press a key on a modern telephone keypad; each key press generates two distinct, precise audio frequencies simultaneously.
In amateur radio, DTMF is used for various control functions, such as sending control signals to a repeater (like an autopatch to dial a phone number - T4B07) or for controlling a remote base station. It is a very reliable method of transmitting short control commands.
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