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7K • Chapter 3
• There is no acknowledgment message sent by the controller when a
command is cleared.
• Any digits following the (#) digit will be considered a new command.
DTMF Interdigit Timer
The controller uses a DTMF Interdigit Timer for the purpose of clearing the
command buffer if a command is not completely entered.
For example, if a user accidentally presses a digit, or if a digit is falsed into the
buffer, or if a user drives out of range or his signal flutters while entering a
command, the command buffer will have only a piece of a command. If the
controller had no time limit between digits, that piece of a command would stay
in the buffer. The controller would confuse it with the next command it receives.
The DTMF interdigit timer works as follows:
• When you release any DTMF key, the timer is started.
• If you do not enter another DTMF digit within the time limit, the controller will
clear the command buffer.
• The interdigit timer initially defaults to 5.0 seconds, but it can be
reprogrammed with a different value if desired.
DTMF Mute Delay
The controller has a DTMF Mute feature that prevents your DTMF commands
from being repeated. This feature can be turned ON and OFF for various
Receiver-Transmitter combinations using the Enable/Disable DTMF Decoder
Mute commands on page 11-9.
Unless your controller has been fitted with the optional Audio Delay Module,
there will be a short burst (40 to 50mS) of DTMF that is repeated at the
beginning of a digit. This short burst occurs because the controller requires
some time to detect the DTMF digit and shut OFF the audio gate.
To reduce the number of bursts, the controller will continue to mute the audio
for a while after you have released the DTMF key. Therefore, if you enter a
string of digits rapidly, there will be only a single burst (caused by the beginning
of the first digit). If you wait too long between digits, the muting will end. The
next digit you enter will cause a short burst at the beginning. The DTMF
Decoder Mute Delay initially defaults to 0.5 seconds, but it can be
reprogrammed with a different value if desired.
3-6
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