Icom IC-746PRO Manual page 151

• Two of the possible signaling formats available on the IC-746PRO
is CTCSS and DTCS.
• Tone squelch or
using selective calling. Only received signal having a matching
tone will open the squelch.
• DTCS function is an another method of communications using
selective calling. Only received signal having a matching 3-digit
code will open the squelch.
Tone
CTCSS operation is a method of communications