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DV MODE OPERATION
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• How to use break-in?
While operating with the digital call sign squelch (p. 151), 
the squelch never opens 
(no audio sounds) even if a call is 
received, unless your own call sign 
(“MY”) is specified.
However, when the call including the “BK ON” signal 
(break-in call) is received, the squelch will open and audio 
sounds even if the call is specified for another station.
Station A Station B
Station C
• Station C calling to Station A with “BK OFF”
Station A Station B
Station C
• Station C calling to Station A with “BK ON”
Station A and B 
are communicating 
using the digital 
call sign squelch.
Station A and B 
are communicating 
using the digital 
call sign squelch.
Station B never hears that 
Station C is calling Station A.
Station B also hears that 
Station C is calling Station A.