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Commands
Disconnect (DISC)
Acknowledge
~CKC)
Receive
(R
C)
Terminate (TERC)
Data Transfer
Initial Conditions
Receive
Reports
ERROR
END
701724 EDGE
Demodulator IBuffer
•
The command signals from the CCM are decoded by the Edge Demodu-
lator Buffer into the following commands:
Disconnect (DISC)
Acknowledge (ACKC)
Recei ve (RC)
Terminate (TERC)
•
The DISC command disables the Line Concentrator trunk thereby pre-
venting the Line Concentrator from connecting an Input Station to that
trunk
o
This is the quiescent condition for the Edge Demodulator/Buffer.
•
The ACKC buffer causes the Edge Demodulator/Buffer to respond to a
valid message by sending an AB2 to the connected Input Station via the
Line Concentrator.
• The RC command enables the Edge Demodulator/Buffer to accept a
message from the Line Concentrator.
•
The TERC command terminates a Receive (RC) command.
•
Whenever the Edge Demodulator/Buffer receives a SEL from the CCM,
it responds with BOP regardless of command status or line condition. In
the absence of a command, the buffer remains in the condition in which it
is placed upon termination (END) of the previous command.
It
is then
conditioned to receive a new command.
Whenever a signal appears on the Reset lead from the CCM, the buffer
is restored to its quiescent condition, and the command which was present,
is dropped. The buffer responds to subsequent SEL with BOP, until another
command is received.
•
If
an RC is present in the Edge Demodulator/Buffer when the RT signal
from the Line Concentrator is sensed, the buffer responds with the AB1
signal which permits the connected Input Station to transmit. The buffer is
conditioned to start phase detection after 8
±
4 ms of unmodulated signal
carrier is received. After detecting a phase change, a bit is transferred
from the line to bit storage within the buffer.
The Edge Demodulator/Buffer then responds to a CCM SEL with RDY
o
The bit is transferred to the CCM on the Data lead with the opposite sense
as received from the line (lor 0). Subsequent bits are transferred from the
line to storage and then to the CCM until a TERC is received from the CCMo
The buffer then inhibits RDY and terminates.
•
The Report signals to the CCM are encoded by the Edge Demodulator/
Buffer to indicate the following conditions:
ERROR (ER), END
•
The Edge Demodulator/Buffer indicates a loss of signal carrier to the
CCM via an ER whenever an RC is present, but after RDY and prior to
TERC.
•
The Edge Demodulator/Buffer reports END whenever it completes the
operations required by each command.
4-36
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