Messages
4-1
Chapter 4
Messages
The controller uses Messages to communicate with users of the repeater. Most
of the controller's messages are remotely programmable via DTMF commands.
Messages may be composed of combinations of CW (Morse) characters,
beeps, DTMF characters, synthesized speech words, and various paging
formats.
Message Buffer
A portion of the controller’s memory is dedicated to the Message Buffer. The
message buffer is used to temporarily store messages that the controller is
asked to send. The message buffer is a FIFO buffer (first-in, first-out), which
means that the first message to arrive in the buffer is the first one to be sent
out. The purpose of the message buffer is to prevent overruns when several of
the controller’s software programs want to send messages at the same time.
Each program sends its message to the message buffer: The messages are
then unloaded and transmitted by a program called the message handler.
Message Handler
The Message Handler needs to know what kind of message it is unloading—
and where it is to go—so that it can operate the proper hardware to send the
message. For example, a DTMF Message requires different hardware than a
speech synthesized message. A message intended for transmitter #1 requires
a different path be set up than a message intended for transmitter #2.
The way to tell the message handler the type of message and the routing of the
message desired is with special control characters. The control characters are
defined next.
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