To Disable The Esc Backward Alarms; Satellite Control Channel (Scc); Scc Framing Structure - Comtech EF Data DMD-2050E Installation And Operation Manual

DMD2050E Universal Satellite Modem
The user can connect whichever systems on the earth stations that they desire to these
Backward Alarms Relays as long as they will supply ground to the Backward Alarm Relay Input in
the "no fault" condition and the ground will be removed in the "faulted" condition.
For example: the user could connect the Demod Summary Fault of the modem to the Backward
Alarm 1 Input, so that if the demod went into Major Alarm (such as a Carrier Loss), Backward
Alarm 1 would be transmitted to the receive end of the link. At the receive end, it would show up
as Rx Backward 1 (Receive Backward Alarm 1).
3.18.1

To Disable the ESC Backward Alarms

If the ESC ALARMS Port will not be used and the Backward Alarm Indications are to be disabled,
you will need to connect pins 19, 11, 22 and 23 to pin 1 (Gnd).
3.19

Satellite Control Channel (SCC)

The SCC format uses a variable overhead rate to transmit an asynchronous data channel in
addition to the normal data channel. The SCC asynchronous mode implemented on the
DMD2050E is "PassThru" Mode.
In Pass Thru Mode, there is no formatting or deformatting of the input data in the buffer, and it is
transmitted on a first-in first-out basis. In band data entering the remote port is inserted into the
user data stream. The in-band data is received and passed on to the user without any
deformatting or depacketizing involved. The maximum in band rate supported is 115200bps.
The Asynchronous Data Interface (J17) is a 9-Pin Female "D" Connector. The data interface is
either RS232 or RS485 via a front panel selection.
See also:
Chapter 5. External Connections
3.19.1

SCC Framing Structure

Each SCC frame consists of the following:
A 10-bit synchronization pattern called the Synchronizing Word.
•
Multiple variable length slots filled with user data.
•
Multiple 10-bit control words that contains eight bits of in-band data (the extra two bits are for
•
the async start/stop).
MN-DMD2050E Revision 2
Theory of Operation
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