     7   6   5   4   3   2   1   0   7   6   5   4   3   2   1   0   7   6   5   4   3   2   1   0   7   6   5   4   3   2   1   0
   +---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+
00 | Action, 0=none                | Alarm duration in seconds     | TX duration in seconds        | RX duration in seconds        |
   +---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+
04 | Channel index, 0-based, little endian                         | Channel select 1=current      | Alarm repeat 0=continuous     |
   +---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+
08 | Voice switch BC dur in min+1  | Area switch BC dur in min+1   | VOX enable                    | RX alarm enable               |
   +---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+

Field details:
 - Action: Specifies the alarm action. 0=none, 1=TX and background, 2=TX and non-local alarm, 3=TX and local alarm
 - Channel select: If 0 use specified channel index else current channel.
 - Alarm repeat: Number of alarm repetitions, 0=continuous.
 - Voice switch broadcast duration: Specifies the time in minutes +1. That is 0=1min, 1=2min, ...
 - Area switch broadcast duration: Specifies the time in minutes +1. That is 0=1min, 1=2min, ...
